Receiving light module, emitting light module and receiving and emitting light module

Abstract

The invention discloses a receiving optical module, a transmitting optical module and a receiving and transmitting optical module, which are used for reducing loss, improving gain and reducing noise. In the receiving optical module, impedance matching is carried out through the first step transformation plane transmission line or the first lumped element network, impedance matching can be realized by adopting a capacitor and an inductor instead of adopting a resistor for impedance matching, the loss in the radio frequency signal transmission process can be reduced, the gain is further improved, and the noise is reduced. In the transmitting optical module, impedance matching is carried out through a second step transformation plane transmission line or a second lumped element network, impedance matching can be realized by adopting a capacitor and an inductor instead of adopting a resistor for impedance matching, the loss in the radio frequency signal transmission process can be reduced, the gain is further improved, and the noise is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication technology, and in particular to a receiving optical module, a transmitting optical module and a transceiving optical module. BACKGROUND

[0002] Compared with the traditional radio frequency transmission link, the radio over fiber (RoF) transmission link has the advantages of large bandwidth, small loss, light weight and anti-electromagnetic interference, and can be applied to the large bandwidth application scenarios of wireless communication systems. The RoF link is characterized in that: first, the conversion from radio frequency signal to optical signal is completed through the electro-optical conversion of the transmitting optical module; then, the remote transmission is completed through the optical fiber; finally, the conversion from optical signal to radio frequency signal is completed through the photoelectric conversion of the receiving optical module, so as to output the radio frequency signal, thereby replacing the microwave assembly or cable to transmit the radio frequency signal. According to the modulation type, the RoF transmission link can be divided into: direct modulation type (i.e., the transmitting optical module adopts a direct modulation laser scheme) and external modulation type (i.e., the transmitting optical module adopts a combination scheme of laser and electro-optical modulator). In the direct modulation type RoF transmission link, the direct modulation laser in the transmitting optical module realizes the electro-optical conversion function, and the photodetector (PD) in the receiving optical module realizes the photoelectric conversion function.

[0003] At present, in the transmitting optical module, since the internal resistance of the direct modulation laser is generally 5-10 ohms, a 40-45 ohm resistor is usually connected in series between the direct modulation laser and the radio frequency transmission circuit connected thereto for impedance matching. However, in actual application, most of the power of the radio frequency signal transmitted by the radio frequency transmission circuit is consumed by the connected 40-45 ohm resistor, resulting in a small power of the radio frequency signal transmitted to the direct modulation laser, and reducing the electro-optical modulation efficiency of the direct modulation laser.

[0004] In addition, in the receiving optical module, since the internal resistance of the photodetector is usually as high as several thousand ohms, a 50 ohm resistor is usually connected in parallel between the photodetector and the radio frequency transmission circuit connected thereto for impedance matching. However, in actual application, the connected 50 ohm resistor will take away a part of the output photocurrent, resulting in a 6dB matching loss of the transmitted radio frequency signal. Therefore, in the RoF transmission link, the current resistance matching scheme of the transmitting optical module and the receiving optical module is all lossy matching, resulting in a low gain and poor noise figure index of the RoF link, which greatly limits the application range of the RoF technology. SUMMARY

[0005] The embodiments of the present application provide a receiving optical module, a transmitting optical module and a transceiving optical module to reduce the loss, improve the gain and reduce the noise.

[0006] In a first aspect, the embodiments of the present application provide a receiving optical module, which comprises a photodetector and a first stepped transformation planar transmission line. The first stepped transformation planar transmission line comprises a first transmission line subsection to an Mth transmission line subsection connected in sequence. The first transmission line subsection is connected with a signal output port of the photodetector. The Mth transmission line subsection is used to connect a radio frequency input end of a radio frequency transmission circuit, so as to realize impedance matching through the first stepped transformation planar transmission line. In the embodiments of the present application, based on the direct current and scattering parameter data actually measured under different input optical powers, different bias voltages and different frequencies, a photodetector circuit model related to the input optical power, the bias voltage and the frequency is established, so as to accurately characterize the photoelectric conversion process of the photodetector. Then, the established photodetector circuit model is used, and based on the requirements of matching a large bandwidth (for example, 10 GHz to 13 GHz) and a transmission coefficient greater than or equal to 0.9, simulation is performed to obtain the first stepped transformation planar transmission line meeting the above requirements. That is, the first stepped transformation planar transmission line needs to be segmented, and the impedances of adjacent segments need to be designed to be different. Based on this, the first stepped transformation planar transmission line is designed to realize impedance matching, which can minimize the loss of the radio frequency signal in the output process, effectively reduce the loss of the radio frequency signal in the output process compared with using a resistor for impedance matching, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and further obtaining a high-performance RoF transmission link.

[0007] In addition, M can be an integer and M≥3, that is, the first stepped transformation planar transmission line is at least divided into three segments. In order to realize impedance matching and meet the requirements of matching a large bandwidth (for example, 10 GHz to 13 GHz) and a transmission coefficient greater than or equal to 0.9, the impedance of at least one of the second transmission line subsection to the M-1th transmission line subsection can be less than the impedance of the first transmission line subsection. Through simulation, it is found that if the impedances of the first transmission line subsection to the Mth transmission line subsection are set to increase in a decreasing trend, impedance matching can also be realized, but when the impedance matching is performed using this impedance change trend, the bandwidth is usually less than 0.5 GHz, resulting in a narrow matching bandwidth and a large limitation of the application range.

[0008] In some embodiments, M≥4, that is, the first stepped transformation planar transmission line is at least divided into four segments, and the impedance change law of the first transmission line subsection to the Mth transmission line subsection is adjusted. For example, the impedance of each of the first transmission line subsection to the Mth transmission line subsection can be sequentially reduced, increased, and then reduced, so as to further improve the transmission coefficient on the basis of matching a large bandwidth.

[0009] In some embodiments, since the first transmission line sub-section connects the signal output port of the photodetector, and the Mth transmission line sub-section connects the corresponding radio frequency transmission circuit, in order to compensate the impedance of the first transmission line sub-section and the Mth transmission line sub-section, the impedance of the first transmission line sub-section to the Mth transmission line sub-section can be first reduced and then increased to be greater than the impedance of the Mth transmission line sub-section, and finally reduced to the impedance of the Mth transmission line sub-section. For example, the impedance of the first transmission line sub-section to the ath transmission line sub-section connected in sequence can be first gradually reduced, and then the impedance of the ath transmission line sub-section to the bth transmission line sub-section connected in sequence can be first gradually increased and increased to be greater than the impedance of the Mth transmission line sub-section. Then, the impedance of the bth transmission line sub-section to the Mth transmission line sub-section connected in sequence can be gradually reduced.

[0010] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (for example, 2.4 GHz, 5 GHz), the impedance of the second transmission line sub-section can be less than the impedance of the first transmission line sub-section and the impedance of the third transmission line sub-section, or the impedance of the third transmission line sub-section can be less than the impedance of the second transmission line sub-section and the impedance of the fourth transmission line sub-section, and the impedance of the second transmission line sub-section is less than the impedance of the first transmission line sub-section. By setting in this way, the inflection point of impedance reduction can be set at the impedance of the second transmission line sub-section or the impedance of the third transmission line sub-section, and the transmission coefficient at certain frequency points can be further improved.

[0011] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (for example, 2.4 GHz, 5 GHz), the impedance of the M-1th transmission line sub-section can be greater than the impedance of the Mth transmission line sub-section and the impedance of the M-2th transmission line sub-section, or the impedance of the M-2th transmission line sub-section can be greater than the impedance of the M-1th transmission line sub-section and the impedance of the M-3th transmission line sub-section, and the impedance of the M-1th transmission line sub-section is greater than the impedance of the Mth transmission line sub-section. By setting in this way, the inflection point of impedance increase can be set at the impedance of the M-1th transmission line sub-section or the impedance of the M-2th transmission line sub-section, and the transmission coefficient at certain frequency points can be further improved.

[0012] For the specific number of transmission line sub-sections, a suitable value can be selected by those skilled in the art based on the needs of impedance matching, large bandwidth, high transmission coefficient, low noise and other performances, as well as the size and cost of the receiving optical module 200 and other considerations. For example, the specific number of transmission line sub-sections can be set to 3-20. In actual application, if the number of transmission line sub-sections is too small, the impedance variation trend of the transmission line sub-sections will not be effective. If the number of transmission line sub-sections is too large, the size will be too large, the loss will increase, and the design and processing difficulty will increase, resulting in increased cost. Therefore, considering the influence of cost and performance, in the embodiments of the present application, 4≤M≤10 is set to balance the influence of cost and performance. For example, M can be 4, 6, 8, 9, 10, etc., which is not limited herein.

[0013] On the basis of matching a large bandwidth, in order to further improve the transmission coefficient, the difference between the impedance of the first transmission line sub-section and the output impedance of the signal output port of the photodetector can be close to zero or equal to zero, and the difference between the impedance of the Mth transmission line sub-section and the input impedance of the radio frequency input end of the corresponding radio frequency transmission circuit can be close to zero or equal to zero.

[0014] In some embodiments, the first stepped-transformed planar transmission line can include, but is not limited to, a stepped-transformed microstrip line or a stepped-transformed stripline. For example, when the first stepped-transformed planar transmission line is set as a stepped-transformed microstrip line, the stepped-transformed microstrip line is divided into the first transmission line sub-section to the Mth transmission line sub-section. When the first stepped-transformed planar transmission line is set as a stepped-transformed stripline, the stepped-transformed stripline is divided into the first transmission line sub-section to the Mth transmission line sub-section.

[0015] In some embodiments, the receiving optical module further includes a first receiving component, a first end of the first receiving component is connected to one of the first transmission line sub-section to the Mth transmission line sub-section, and a second end of the first receiving component is used to connect a power supply input port or a ground input port. The first receiving component is used to couple the signal of the power supply input port or the ground input port to the transmission line sub-section connected thereto and block the radio frequency signal. By this arrangement, a direct current voltage or a ground voltage can be input through the first receiving component, and radio frequency signal leakage can be blocked or reduced.

[0016] In some embodiments, in order to reduce the influence of the first receiving component on the impedance and radio frequency signal leakage of each transmission line sub-section in the first stepped-transformed planar transmission line, the first end of the first receiving component can be connected to the connection between the first transmission line sub-section and the second transmission line sub-section.

[0017] In some embodiments, the first receiving component can include a first quarter-wavelength transmission line or a first receiving inductance, so that a simple device can be used to not only transmit voltage but also block radio frequency signals.

[0018] In some embodiments, when the second end of the first receiving component is used to connect the power input port, the receiving optical module further comprises a first receiving ground capacitor and a second receiving component, wherein a first electrode of the first receiving ground capacitor is connected with the first ground port of the photodetector, a second electrode of the first receiving ground capacitor is used to connect the ground input port, a first end of the second receiving component is connected with the first ground port of the photodetector, and a second end of the second receiving component is used to connect the power input port. The second receiving component and the first receiving ground capacitor are respectively used to couple the signal of the power input port to the first ground port of the photodetector, and the second receiving component is further used to block the radio frequency signal. In this way, the second receiving component and the first receiving ground capacitor can be grounded, and the radio frequency signal leakage can be blocked or reduced.

[0019] In some embodiments, the second receiving component comprises a second quarter-wavelength transmission line or a second receiving inductor, so that simple devices can be used to realize both transmission of voltage and blocking or reducing of the radio frequency signal.

[0020] In some embodiments, when the second end of the first receiving component is used to connect the power input port, the receiving optical module further comprises a second receiving ground capacitor, wherein a first electrode of the second receiving ground capacitor is connected with the first ground port of the photodetector, and a second electrode of the second receiving ground capacitor is used to connect the ground input port. In this way, simple devices can be used to realize both transmission of voltage and blocking or reducing of the radio frequency signal.

[0021] In some embodiments, the receiving optical module further comprises a third receiving ground capacitor, wherein a first electrode of the third receiving ground capacitor is connected with the second ground port of the photodetector, and a second electrode of the third receiving ground capacitor is used to connect the ground input port. In this way, simple devices can be used to realize both transmission of voltage and blocking or reducing of the radio frequency signal.

[0022] In a second aspect, the embodiments of the present application provide another kind of receiving optical module. The receiving optical module comprises a photodetector and a first lumped element network. The first end of the first lumped element network is connected to the signal output port of the photodetector, and the second end of the first lumped element network is used to connect the RF input end of the RF transmission circuit to perform impedance matching through the first lumped element network. In order to reduce the loss, the first lumped element network comprises a plurality of receiving matching capacitors and a plurality of receiving matching inductors. The plurality of receiving matching inductors are connected in series between the signal output port of the photodetector and the RF input end of the RF transmission circuit. The two ends of at least part of the receiving matching inductors are respectively connected to the first end of one receiving matching capacitor. The second end of the plurality of receiving matching capacitors is used to connect the ground input port. In this way, the impedance matching can be realized by using capacitors and inductors instead of resistors, and the loss in the process of RF signal transmission can be reduced.

[0023] In some embodiments of the present application, the DC and scattering parameter data under different input optical powers, different bias voltages and different frequencies can be measured to establish a photodetector circuit model related to the input optical power, the bias voltage and the frequency, so as to accurately characterize the photoelectric conversion process of the photodetector. Then, the established photodetector circuit model is used to simulate the number of capacitors and inductors, and the change rule of the capacitance value of the capacitor and the inductance value of the inductor, based on the requirements of matching a large bandwidth (for example, 10GHz-13GHz) and a transmission coefficient greater than or equal to 0.9. In the direction from the signal output port of the photodetector to the RF input end of the RF transmission circuit, the inductance value of the plurality of receiving matching inductors decreases, and the capacitance value of the plurality of receiving matching capacitors decreases. Based on this, the capacitors and inductors in the first lumped element network are designed to realize impedance matching, which can minimize the loss of the RF signal in the output process. Compared with using resistors for impedance matching, the loss of the RF signal in the output process can be effectively reduced, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and further obtaining a high-performance RoF transmission link.

[0024] In some embodiments, the plurality of receiving matching inductances comprises a first receiving matching inductance and a second receiving matching inductance, and the plurality of receiving matching capacitances comprises a first receiving matching capacitance, a second receiving matching capacitance, and a third receiving matching capacitance, wherein a first end of the first receiving matching inductance, a first end of the first receiving matching capacitance, and a first end of the first lumped element network are connected to each other, a second end of the first receiving matching inductance, a first end of the second receiving matching inductance, and a first end of the second receiving matching capacitance are connected to each other, a second end of the second receiving matching inductance, a first end of the third receiving matching capacitance, and a second end of the first lumped element network are connected to each other, and a second end of the first receiving matching capacitance, a second end of the second receiving matching capacitance, and a second end of the third receiving matching capacitance are connected to the ground input port. In this way, the first lumped element network can be implemented by using a simple structure to achieve impedance matching.

[0025] In some embodiments, the receiving optical module further comprises a third receiving inductance, a first end of the third receiving inductance is connected to the signal output port of the photodetector, and a second end of the third receiving inductance is connected to the power supply input port. In this way, a simple device can be used to not only transmit voltage but also block radio frequency signals.

[0026] In some embodiments, the receiving optical module further comprises a fourth receiving ground capacitance, a first electrode of the fourth receiving ground capacitance is connected to the first ground port of the photodetector, and a second electrode of the fourth receiving ground capacitance is connected to the ground input port. In this way, a simple device can be used to not only transmit voltage but also block or reduce the amount of radio frequency signals.

[0027] In some embodiments, the receiving optical module further comprises a fifth receiving ground capacitance, a first electrode of the fifth receiving ground capacitance is connected to the second ground port of the photodetector, and a second electrode of the fifth receiving ground capacitance is connected to the ground input port. In this way, a simple device can be used to not only transmit voltage but also block or reduce the amount of radio frequency signals.

[0028] In a third aspect, the embodiments of the present application provide a transmitting optical module, which comprises a direct modulation laser and a second stepped transformation planar transmission line, the second stepped transformation planar transmission line comprises a first transmission line subsegment to an Nth transmission line subsegment connected in sequence, the first transmission line subsegment is connected to a radio frequency output end of a radio frequency transmission circuit, and the Nth transmission line subsegment is connected to a signal input port of the direct modulation laser to achieve impedance matching through the second stepped transformation planar transmission line.

[0029] In the present application, based on the DC current (I)-voltage (V) data, scattering parameter data and output different optical power under different bias voltage and different frequency actually measured, the direct modulation laser circuit model related to bias voltage, frequency and output optical power can be established to accurately characterize the electro-optical conversion process of the direct modulation laser. Then, the established laser circuit model is used, and based on the requirements of matching a large bandwidth (for example, 2GHz-6GHz) and a transmission coefficient greater than or equal to 0.9, simulation is performed to obtain a second ladder transformation planar transmission line meeting the above requirements. That is, the second ladder transformation planar transmission line needs to be segmented, and the impedance of adjacent segments needs to be designed to be different. Based on this, the second ladder transformation planar transmission line is designed to realize impedance matching, which can minimize the loss of the radio frequency signal in the output process. Compared with using resistance for impedance matching, the loss of the radio frequency signal in the output process can be effectively reduced, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and further obtaining a high-performance RoF transmission link.

[0030] In addition, N can be an integer and N≥3, that is, the second ladder transformation planar transmission line is divided into at least 3 segments. In order to perform impedance matching and meet the requirements of matching a large bandwidth (for example, 2GHz-6GHz) and a transmission coefficient greater than or equal to 0.9, the impedance of at least one of the second transmission line subsection to the N-1 transmission line subsection can be less than the impedance of the N transmission line subsection.

[0031] In some embodiments, N≥5, that is, the second ladder transformation planar transmission line is divided into at least 5 segments, and the impedance variation law of the first transmission line subsection to the N transmission line subsection is adjusted. For example, the impedance of each of the first transmission line subsection to the N transmission line subsection can be sequentially increased, decreased, increased, and decreased, so as to further improve the transmission coefficient on the basis of matching a large bandwidth.

[0032] In some embodiments, since the first transmission line sub-section connects the corresponding radio frequency transmission circuit, and the Nth transmission line sub-section connects the direct modulation laser, in order to compensate the impedance of the first transmission line sub-section and the Nth transmission line sub-section, the impedance of the first transmission line sub-section to the Nth transmission line sub-section can be sequentially increased first, then sequentially decreased to be less than the impedance of the Nth transmission line sub-section, then sequentially increased to be greater than the impedance of the Nth transmission line sub-section, and finally sequentially decreased to the impedance of the Nth transmission line sub-section. For example, the impedance of the sequentially connected first transmission line sub-section to the cth transmission line sub-section is gradually increased. And since the Nth transmission line sub-section connects the direct modulation laser, in order to compensate the impedance of the Nth transmission line sub-section, the impedance of the sequentially connected cth transmission line sub-section to the dth transmission line sub-section can be decreased first, and the impedance of the dth transmission line sub-section is decreased to be less than the input impedance of the direct modulation laser. Then, the impedance of the sequentially connected dth transmission line sub-section to the eth transmission line sub-section is gradually increased, and the impedance of the eth transmission line sub-section is increased to be greater than the input impedance of the direct modulation laser. Then, the impedance of the sequentially connected eth transmission line sub-section to the Nth transmission line sub-section is gradually decreased.

[0033] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (such as 2.4 GHz, 5 GHz), the impedance of the second transmission line sub-section can be greater than the impedance of the first transmission line sub-section and the impedance of the third transmission line sub-section, or the impedance of the third transmission line sub-section can be greater than the impedance of the second transmission line sub-section and the impedance of the fourth transmission line sub-section, and the impedance of the second transmission line sub-section is greater than the impedance of the first transmission line sub-section. By setting in this way, the inflection point of the first increase in impedance can be set at the impedance of the second transmission line sub-section or the impedance of the third transmission line sub-section, and the transmission coefficient at certain frequency points can be further improved.

[0034] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (such as 2.4 GHz, 5 GHz), the impedance of the N-1th transmission line sub-section can be greater than the impedance of the Nth transmission line sub-section and the impedance of the N-2th transmission line sub-section, the impedance of the N-2th transmission line sub-section can be less than the impedance of the Nth transmission line sub-section and the impedance of the N-3th transmission line sub-section, or the impedance of the N-2th transmission line sub-section can be greater than the impedance of the N-1th transmission line sub-section and the impedance of the N-3th transmission line sub-section, the impedance of the N-1th transmission line sub-section can be greater than the impedance of the Nth transmission line sub-section, and the impedance of the N-3th transmission line sub-section can be less than the impedance of the Nth transmission line sub-section and the impedance of the N-4th transmission line sub-section. By setting in this way, the inflection point of the second increase in impedance can be set at the impedance of the N-1th transmission line sub-section or the impedance of the N-2th transmission line sub-section, and the transmission coefficient at certain frequency points can be further improved.

[0035] In some embodiments, for the specific number of transmission line sub-sections, the skilled in the art can select appropriate values based on the needs of performance such as impedance matching, large bandwidth, high transmission coefficient and low noise, and considerations such as the size and cost of the transmitting optical module. For example, the specific number of transmission line sub-sections can be set to 3-20. In practical applications, if the number of transmission line sub-sections is too small, the impedance variation trend of the transmission line sub-sections will not be effective. If the number of transmission line sub-sections is too large, the size will be too large, the loss will increase, and the design and processing difficulty will increase, resulting in increased cost. Therefore, by considering the influence of cost and performance, in the embodiments of the present application, 5≤N≤10 is set to balance the influence of cost and performance. For example, N can be 5, 6, 8, 9, 10, etc., which is not limited herein.

[0036] In some embodiments, on the basis of matching a large bandwidth, in order to further improve the transmission coefficient, the difference between the impedance of the first transmission line sub-section and the output impedance of the radio frequency output end of the radio frequency transmission circuit connected thereto can be close to zero or equal to zero, and the difference between the impedance of the Nth transmission line sub-section and the input impedance of the signal input port of the direct modulation laser can be close to zero or equal to zero.

[0037] In some embodiments, the second stepped transformation planar transmission line includes but is not limited to a stepped transformation microstrip line or a stepped transformation stripline. For example, when the second stepped transformation planar transmission line is set as a stepped transformation microstrip line, the stepped transformation microstrip line is divided into the first transmission line sub-section to the Nth transmission line sub-section. When the second stepped transformation planar transmission line is set as a stepped transformation stripline, the stepped transformation stripline is divided into the first transmission line sub-section to the Nth transmission line sub-section.

[0038] In some embodiments, the transmitting optical module further includes a first transmitting component, a first end of the first transmitting component is connected to one of the first transmission line sub-section to the Nth transmission line sub-section, and a second end of the first transmitting component is used to connect the power supply input port. And the second receiving component is used to couple the signal of the power supply input port to the transmission line sub-section connected thereto and block the radio frequency signal. In this way, the second receiving component can be used to input direct current voltage and block or reduce radio frequency signal leakage.

[0039] In some embodiments, in order to reduce the influence of the first transmitting component on the impedance and radio frequency signal leakage of each transmission line sub-section in the second stepped transformation planar transmission line, the first end of the first transmitting component can be connected to the connection between the first transmission line sub-section and the second transmission line sub-section.

[0040] In some embodiments, the first transmitting component includes a third quarter wavelength transmission line or a first transmitting inductor, so that simple devices can be used to not only transmit voltage but also block or reduce the amount of radio frequency signal passing through.

[0041] In some embodiments, the transmitting optical module further comprises a first transmitting ground capacitor, a first electrode of the first transmitting ground capacitor is connected with the ground port of the direct modulation laser, and a second end of the first transmitting ground capacitor is used to connect the ground input port, so that a simple device can be used to realize both transmission of voltage and blocking or reducing of RF signal passing amount.

[0042] In some embodiments, the transmitting optical module further comprises a second transmitting ground capacitor, a first electrode of the second transmitting ground capacitor is connected with the signal input port of the direct modulation laser, and a second end of the second transmitting ground capacitor is used to connect the ground input port, so that a simple device can be used to realize both transmission of voltage and blocking or reducing of RF signal passing amount.

[0043] In the fourth aspect, the embodiments of the present application provide still another transmitting optical module, which comprises a direct modulation laser and a second lumped element network, wherein a first end of the second lumped element network is used to connect a RF output end of a RF transmission circuit, a second end of the second lumped element network is connected with a signal input port of the direct modulation laser to perform impedance matching through the second lumped element network. In order to reduce loss, the second lumped element network comprises a plurality of transmitting matching capacitors and a plurality of transmitting matching inductors, the plurality of transmitting matching inductors are connected in series between the RF output end of the RF transmission circuit and the signal input port of the direct modulation laser, two ends of at least part of the transmitting matching inductors are connected with a first end of one transmitting matching capacitor in one-to-one correspondence, and second ends of the plurality of transmitting matching capacitors are used to connect a ground input port. In this way, impedance matching can be realized by using capacitors and inductors instead of resistors, and loss in the process of RF signal transmission can be reduced.

[0044] And, in the present application, based on the DC current (I)-voltage (V) data, scattering parameter data and output different optical power actually measured under different bias voltage and different frequency, the direct modulation laser circuit model related to bias voltage, frequency and output optical power can be established to accurately characterize the electro-optical conversion process of the direct modulation laser. Then, the established laser circuit model is used, and based on the requirements of matching a large bandwidth (for example, 2GHz-6GHz) and a transmission coefficient greater than or equal to 0.9, simulation is performed to obtain the number of capacitors and inductors that meet the above requirements, and the change law of the capacitance value of the capacitor and the inductance value of the inductor. Among them, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance values of the plurality of transmitting matching inductors show an increasing trend, and the capacitance values of the plurality of transmitting matching capacitors show an increasing trend. Based on this, the capacitors and inductors in the second lumped element network are designed to achieve impedance matching, which can minimize the loss of the radio frequency signal in the output process, effectively reduce the loss of the radio frequency signal in the output process compared with using resistance for impedance matching, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and thus obtaining a high-performance RoF transmission link.

[0045] In some embodiments, the plurality of transmitting matching inductors includes a first transmitting matching inductor, a second transmitting matching inductor, and a third transmitting matching inductor, and the plurality of transmitting matching capacitors includes a first transmitting matching capacitor, a second transmitting matching capacitor, and a third transmitting matching capacitor, wherein a first end of the first transmitting matching inductor, a first end of the first transmitting matching capacitor, and a first end of the second lumped element network are connected to each other, a second end of the first transmitting matching inductor, a first end of the second transmitting matching inductor, and a first end of the second transmitting matching capacitor are connected to each other, a second end of the second transmitting matching inductor, a first end of the third transmitting matching inductor, and a first end of the third transmitting matching capacitor are connected to each other, a second end of the third transmitting matching inductor is connected to a second end of the second lumped element network, and a second end of the first transmitting matching capacitor, a second end of the second transmitting matching capacitor, and a second end of the third transmitting matching capacitor are all used to connect the ground input port. With this arrangement, the second lumped element network can be implemented using a simple structure to achieve impedance matching.

[0046] In some embodiments, the transmitting optical module further includes a second transmitting inductor, a first end of the second transmitting inductor is connected to the signal input port of the direct modulation laser, and a second end of the second transmitting inductor is used to connect the power supply input port. With this arrangement, simple devices can be used to not only transmit voltage but also block or reduce the amount of radio frequency signal passing through.

[0047] In some embodiments, the transmitting optical module further comprises a third transmitting ground capacitor, a first electrode of the third transmitting ground capacitor is connected with the ground port of the direct modulation laser, and a second electrode of the third transmitting ground capacitor is used to connect the ground input port. With the arrangement, simple devices can be used to realize both transmission of voltage and blocking or reducing of RF signal passing amount.

[0048] In some embodiments, the transmitting optical module further comprises a fourth transmitting ground capacitor, a first electrode of the fourth transmitting ground capacitor is connected with the ground port of the direct modulation laser, and a second electrode of the fourth transmitting ground capacitor is used to connect the ground input port. With the arrangement, simple devices can be used to realize both transmission of voltage and blocking or reducing of RF signal passing amount.

[0049] In the fifth aspect, the embodiments of the present application further provide a transceiving optical module, which comprises one or more receiving optical modules and one or more transmitting optical modules. The receiving optical module is the receiving optical module in the first aspect or the receiving optical module in any of the embodiments of the first aspect, or the receiving optical module is the receiving optical module in the second aspect or the receiving optical module in any of the embodiments of the second aspect. And the transmitting optical module is the transmitting optical module in the third aspect or the transmitting optical module in any of the embodiments of the third aspect, or the transmitting optical module is the transmitting optical module in the fourth aspect or the transmitting optical module in any of the embodiments of the fourth aspect. Due to the transmitting optical module and the receiving optical module described above, the loss of RF signal in the output process can be reduced as much as possible, compared with using a resistor for impedance matching, the loss of RF signal in the output process can be effectively reduced, so as to improve the gain of the entire RoF network system, reduce the noise coefficient, and thus a high-performance RoF transmission link can be obtained.

[0050] In the sixth aspect, the embodiments of the present application further provide an electronic device, which comprises the receiving optical module in the first aspect or the receiving optical module in any of the embodiments of the first aspect, or the receiving optical module in the second aspect or the receiving optical module in any of the embodiments of the second aspect; or the transmitting optical module in the third aspect or the transmitting optical module in any of the embodiments of the third aspect, or the transmitting optical module in the fourth aspect or the transmitting optical module in any of the embodiments of the fourth aspect; or the transceiving optical module in the fifth aspect. The electronic device can be various devices, such as a server, a routing device, a switching device or other communication devices. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1a Fig. 1 is a structural schematic diagram of an optical wireless network system in the related art;

[0052] Figure 1b Fig. 2 is another structural schematic diagram of an optical wireless network system in the related art;

[0053] Figure 2 Fig. 3 is a structural block diagram of a receiving optical module provided by the embodiments of the present application;

[0054] Figure 3a A structure diagram of a first ladder conversion planar transmission line, a radio frequency transmission circuit and a photoelectric detector provided by the embodiment of the present application;

[0055] Figure 3b A structure diagram of a first ladder conversion planar transmission line, a radio frequency transmission circuit and a photoelectric detector provided by the embodiment of the present application;

[0056] Figure 3c A structure diagram of a first ladder conversion planar transmission line, a radio frequency transmission circuit and a photoelectric detector provided by the embodiment of the present application;

[0057] Figure 4 A three-dimensional structure diagram of a receiving optical module and an optical fiber provided by the embodiment of the present application;

[0058] Figure 5a An equivalent circuit structure diagram of a receiving optical module provided by the embodiment of the present application;

[0059] Figure 5b A structure diagram of a receiving optical module provided by the embodiment of the present application; Figure 5a A corresponding specific structure diagram;

[0060] Figure 6 An equivalent circuit structure diagram of a receiving optical module provided by the embodiment of the present application;

[0061] Figure 7 An equivalent circuit structure diagram of a receiving optical module provided by the embodiment of the present application;

[0062] Figure 8 A structure block diagram of a transmitting optical module provided by the embodiment of the present application;

[0063] Figure 9 A structure diagram of a second ladder conversion planar transmission line, a radio frequency transmission circuit and a direct modulation laser provided by the embodiment of the present application;

[0064] Figure 10a A structure diagram of a transmitting optical module provided by the embodiment of the present application;

[0065] Figure 10b A structure diagram of a transmitting PCB provided by the embodiment of the present application;

[0066] Figure 11 An equivalent circuit structure diagram of a receiving optical module provided by the embodiment of the present application;

[0067] Figure 12 An equivalent circuit structure diagram of a transmitting optical module provided by the embodiment of the present application.

[0068] Reference signs:

[0069] 10 - center side communication device; 11 - baseband signal processing circuit; 12 - first radio frequency transmission circuit; 13 / 23 / 500 - transmitting optical module; 15 / 24 - transceiving optical module; 20 - remote side communication device; 14 / 21 / 200 - receiving optical module; 22 - second radio frequency transmission circuit; 211 - photodetector; 212 - first ladder conversion plane transmission line; 213 - housing; 2131 - accommodating space; 214 - first lumped element network; 310 - first receiving component; 311 - first quarter wavelength transmission line; 320 - second receiving component; 411 - metal shielding layer; 412 - grounding line; 413 - switching line; 414 - power supply transmission line; 511 - directly modulated laser; 512 - second ladder conversion plane transmission line; 513 - second lumped element network; 610 - first transmitting component; CP1 - first receiving grounding capacitor; CP2 - second receiving grounding capacitor; CP3 - third receiving grounding capacitor; CP4 - fourth receiving grounding capacitor; CP5 - fifth receiving grounding capacitor; CP6 - sixth receiving grounding capacitor; LP1 - first receiving inductor; LP2 - second receiving inductor; LP3 - third receiving inductor; CY1 - first transmitting grounding capacitor; CY2 - second transmitting grounding capacitor; CY3 - third transmitting grounding capacitor; CY4 - fourth transmitting grounding capacitor; LY1 - first transmitting inductor; LY2 - second transmitting inductor; Lm1 - first receiving matching inductor; Lm2 - second receiving matching inductor; Ln1 - first transmitting matching inductor; Ln2 - second transmitting matching inductor; Ln3 - third transmitting matching inductor; Cm1 - first receiving matching capacitor; Cm2 - second receiving matching capacitor; Cm3 - third receiving matching capacitor; Cn1 - first transmitting matching capacitor; Cn2 - second transmitting matching capacitor; Cn3 - third transmitting matching capacitor; G LD - ground port; S LD - signal input port; F1 - first direction; F2 - second direction; S PD - signal output port; G PD1 - first ground port; G PD2 - second ground port. DETAILED DESCRIPTION

[0070] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. The specific operation methods in the method embodiment can also be applied to the device embodiment or the system embodiment. It should be noted that in the description of the present application, "multiple" can be understood as "at least two". In addition, it should be understood that in the description of the present application, the words "first", "second", etc. are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating or implying order.

[0071] It should be noted that the same reference signs in the drawings of the present application represent the same or similar structures, and thus repeated description thereof will be omitted. The words expressing position and direction described in the present application are described with reference to the drawings, but can be changed as needed, and the changes made are included in the scope of protection of the present application. The drawings of the present application are only used to show the relative positional relationship and do not represent the true proportion.

[0072] The receiving optical module, the transmitting optical module and the transceiving optical module provided by the embodiments of the present application are described below with reference to the drawings.

[0073] The RoF transmission link can be divided into direct modulation type and external modulation type according to the modulation type. Among them, the direct modulation type RoF transmission link has the advantages of effective low cost, high integration, etc., and the application is the most mature. The embodiments of the present application mainly improve the transmitting optical module and the receiving optical module in the direct modulation type RoF transmission link.

[0074] Figure 1a It is a structural schematic diagram of an optical wireless network system in the related art. Referring to Figure 1a , the RoF network system can include a center side communication device 10 and a remote side communication device 20, and the center side communication device 10 and the remote side communication device 20 are connected through an optical fiber. The center side communication device 10 includes a baseband signal processing circuit 11, a first radio frequency transmission circuit 12 and a transmitting optical module 13, the output end of the baseband signal processing circuit 11 is connected with the radio frequency transmission end of the first radio frequency transmission circuit 12, the radio frequency output end of the first radio frequency transmission circuit 12 is connected with the radio frequency input port of the transmitting optical module 13, and the output end of the transmitting optical module 13 is used to connect the optical fiber. The remote side communication device 20 includes a receiving optical module 21 and a second radio frequency transmission circuit 22, the input end of the receiving optical module 21 is used to connect the optical fiber, and the radio frequency output port of the receiving optical module 21 is connected with the radio frequency input end of the second radio frequency transmission circuit 22.

[0075] In work, the center side communication device 10 generates a baseband signal, and converts the baseband signal into a radio frequency signal through the baseband signal processing circuit 11 and the first radio frequency transmission circuit 12, and then converts the radio frequency signal into an optical signal through the transmitting optical module 13, and then transmits the optical signal to the remote side communication device 20 through the optical fiber. In the remote side communication device 20, the received optical signal is converted into a radio frequency signal through the receiving optical module 21, and then the radio frequency signal is transmitted out through the second radio frequency transmission circuit 22.

[0076] Figure 1b It is another structural schematic diagram of an optical wireless network system in the related art. Referring to Figure 1b, the RoF network system can include: a center side communication device 10 and a remote side communication device 20, and the center side communication device 10 and the remote side communication device 20 are connected through an optical fiber. The center side communication device 10 includes a baseband signal processing circuit 11, a first radio frequency transmission circuit 12, and a transceiving optical module 15, and the transceiving optical module 15 can include a transmitting optical module 13 and a receiving optical module 14. Wherein, the output end of the baseband signal processing circuit 11 is connected with the first radio frequency transmission end of the first radio frequency transmission circuit 12, the radio frequency output end of the first radio frequency transmission circuit 12 is connected with the radio frequency input port of the transmitting optical module 13, and the output end of the transmitting optical module is used for connecting the optical fiber. The radio frequency input end of the first radio frequency transmission circuit 12 is connected with the radio frequency output port of the receiving optical module 14, and the input end of the receiving optical module 14 is used for connecting the optical fiber. The remote side communication device 20 includes a transceiving optical module 24 and a second radio frequency transmission circuit 22, and the transceiving optical module 24 can include a transmitting optical module 23 and a receiving optical module 21. Wherein, the input end of the receiving optical module 21 is used for connecting the optical fiber, and the radio frequency output port of the receiving optical module 21 is connected with the radio frequency input end of the second radio frequency transmission circuit 22. The radio frequency input port of the transmitting optical module 23 is connected with the radio frequency output end of the second radio frequency transmission circuit 22, and the output end of the transmitting optical module 23 is used for connecting the optical fiber. It can be understood that the transceiving optical module can be one or more, and the transmitting optical module and the receiving optical module in the transceiving optical module can also be one or more, which is not limited here.

[0077] In work, the center side communication device 10 generates a baseband signal, and converts the baseband signal into a radio frequency signal through the baseband signal processing circuit 11 and the first radio frequency transmission circuit 12. Then, the radio frequency signal is converted into an optical signal through the transmitting optical module 13, and is transmitted to the remote side communication device 20 through the optical fiber. In the remote side communication device 20, the received optical signal is converted into a radio frequency signal through the receiving optical module 21, and the radio frequency signal is transmitted out through the second radio frequency transmission circuit 22. Moreover, the second radio frequency transmission circuit 22 can also receive a radio frequency signal, and output the received radio frequency signal to the transmitting optical module 23. The radio frequency signal is converted into an optical signal through the transmitting optical module 23, and is transmitted to the center side communication device 10 through the optical fiber. In the center side communication device 10, the received optical signal is converted into a radio frequency signal through the receiving optical module 14, and is output to the first radio frequency transmission circuit 12. In some embodiments, Figure 1b The first radio frequency transmission circuit 12 in the center side communication device 10 not only has the function of transmitting a radio frequency signal to the transmitting optical module 13, but also has the function of receiving a radio frequency signal output from the receiving optical module 14. Moreover, the second radio frequency transmission circuit 22 not only has the function of receiving a radio frequency signal output from the receiving optical module 21, but also has the function of receiving a radio frequency signal output from an external device (such as a terminal device), and outputting the received radio frequency signal output from the external device to the transmitting optical module 23 after a series of processing.

[0078] In RoF transmission links, the transmitting optical module typically uses a directly modulated laser. Since the internal resistance of a directly modulated laser is generally 5–10 ohms, it is usually used in RF transmission circuits (e.g., Figure 1a and Figure 1b The first radio frequency transmission circuit 12 or Figure 1b A 40-45 ohm resistor is connected in series between the second RF transmission circuit 22 and the directly modulated laser to achieve impedance matching. However, in practical applications, a large portion of the power of the RF signal transmitted by the RF transmission circuit is consumed by the series 40-45 ohm resistor, resulting in a reduction in the power of the RF signal transmitted to the directly modulated laser and a decrease in the electro-optic modulation efficiency of the directly modulated laser.

[0079] Furthermore, in RoF transmission links, photodetectors are typically used in the receiving optical module. Since the internal resistance of photodetectors is typically as high as several thousand ohms, they are usually used in radio frequency transmission circuits (e.g., Figure 1a and Figure 1b The second radio frequency transmission circuit 22 or Figure 1b A 50-ohm resistor is connected in parallel with the first radio frequency transmission circuit 12) in order to achieve impedance matching. However, in practical applications, the parallel 50-ohm resistor will divert a portion of the output photocurrent, resulting in a 6dB matching loss in the power of the radio frequency signal output by the photodetector.

[0080] Therefore, in RoF transmission links, the current resistance matching schemes for both the transmitting and receiving optical modules are lossy matching, resulting in low gain (e.g., -45dB to 25dB) and poor noise figure (e.g., 35dB to 56dB) for the RoF link, greatly limiting the application scope of RoF technology. To address this, embodiments of this application provide a transmitting and receiving optical module to reduce losses, improve gain, and reduce noise.

[0081] The structure of the receiving optical module provided in this application will be described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative of the specific structure of the receiving optical module. In specific implementations, the specific structure of the receiving optical module is not limited to the structure provided in the embodiments of this invention, and may also be other structures known to those skilled in the art based on the same concept. No specific limitations are made here.

[0082] Figure 2 A structural block diagram of a receiving optical module provided in an embodiment of this application is shown below. Figure 2 The receiving optical module 200 provided in this application embodiment may include a photodetector 211 and a first step-conversion plane transmission line 212. The signal output port S of the photodetector 211... PDThe first stepped transformation planar transmission line 212 is connected to the radio frequency input end of the corresponding radio frequency transmission circuit 110 for impedance matching through the first stepped transformation planar transmission line 212. The input end of the photodetector 211 is used to input an optical signal, and the optical signal is converted into a radio frequency signal after photoelectric conversion, and the radio frequency signal is input to the corresponding radio frequency transmission circuit 110 through the first stepped transformation planar transmission line 212, and the radio frequency signal is output through the radio frequency transmission circuit 110. The photodetector involved in the present application can include one or more of photodiodes (PD), for example, the photodiode includes one or more of a PIN photodiode (PIN-PD), an avalanche photodiode (APD). In some embodiments, the photodetector can be provided as a PD chip, and the PD chip can include various structures, for example, the PD chip can include a ground-signal-ground (GSG) type PD chip or a ground-signal (GS) type PD chip, wherein the GSG type PD chip can have three ports: a signal output port, a first ground port and a second ground port. The GS type PD chip can have two ports: a signal output port and a first ground port. In some embodiments, the connection mode between the signal output port of the PD chip and the first stepped transformation planar transmission line can be designed according to the specific morphology of the PD chip. Exemplarily, the connection mode includes but is not limited to welding, wire bonding (such as gold wire bonding) and the like.

[0083] In some embodiments of the present application, based on the measured direct current, scattering (S) parameter data under different input optical powers, different bias voltages and different frequencies, a photodetector circuit model related to the input optical power, the bias voltage and the frequency can be established to accurately characterize the photoelectric conversion process of the photodetector. The photodetector circuit model can include three regions: a direct current parameter region, a chip intrinsic region and a parasitic parameter region. The direct current parameter region includes a voltage-controlled current source and a diode connected in parallel to represent the direct current parameter characteristics of the photodetector by using the voltage-controlled current source and the diode in parallel. The chip intrinsic region includes a first capacitor and a first resistor to represent the junction capacitance of the photodetector by using the first capacitor (the junction capacitance is a variable capacitance, and the junction capacitance is related to the bias voltage and the optical power), and to represent the drift resistance of the photodetector by using the first resistor (the drift resistance is a variable resistance, and the drift resistance is related to the bias voltage and the optical power). The parasitic parameter region includes a second capacitor, a second resistor and a first inductor to represent the parasitic resistance of the photodetector by using the second resistor, to represent the parasitic inductance of the photodetector by using the first inductor, and to represent the parasitic capacitance of the photodetector by using the second capacitor.

[0084] Based on the established photoelectric detector circuit model, and based on the requirements of matching a large bandwidth (for example, 10GHz-13GHz) and a transmission coefficient greater than or equal to 0.9, simulation is performed to obtain a first ladder-transformed planar transmission line that meets the above requirements. That is, the first ladder-transformed planar transmission line needs to be segmented, and the impedances of adjacent segments need to be designed to be different. Based on this, the first ladder-transformed planar transmission line is designed to achieve impedance matching, which can minimize the loss of the radio frequency signal in the output process. Compared with using a resistor for impedance matching, the loss of the radio frequency signal in the output process can be effectively reduced, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and further obtaining a high-performance RoF transmission link.

[0085] In some embodiments, the first ladder-transformed planar transmission line 212 can include sequentially connected 1st transmission line sub-segment to Mth transmission line sub-segment, the 1st transmission line sub-segment is connected with the signal output port S PD of the photoelectric detector 211, and the Mth transmission line sub-segment is connected with the radio frequency input end of the radio frequency transmission circuit 110. In some examples, the receiving optical module 200 of the present application can be applied to the remote side communication device 20 in the scenario shown in FIG. 1, and the Mth transmission line sub-segment connected radio frequency transmission circuit 110 can be the second radio frequency transmission circuit 22. In yet other examples, the receiving optical module 200 of the present application can be applied to the central side communication device 10 in the scenario shown in FIG. 2, and the Mth transmission line sub-segment connected radio frequency transmission circuit 110 can be the first radio frequency transmission circuit 12. Figure 1a Figure 1b Figure 1b

[0086] In addition, M can be an integer and M≥3, that is, the first ladder-transformed planar transmission line 212 is divided into at least three segments. In order to perform impedance matching and meet the requirements of matching a large bandwidth (for example, 10GHz-13GHz) and a transmission coefficient greater than or equal to 0.9, the impedance of at least one of the 2nd transmission line sub-segment to the M-1th transmission line sub-segment can be less than the impedance of the 1st transmission line sub-segment. Through simulation, it is found that if the impedances of the 1st transmission line sub-segment to the Mth transmission line sub-segment are set to increase in an increasing trend from small to large, impedance matching can also be achieved. However, when using this impedance variation trend for impedance matching, the bandwidth is usually less than 0.5GHz, resulting in a relatively narrow matching bandwidth and a relatively large limitation on the application range.

[0087] In order to match a larger bandwidth and improve the transmission coefficient, the difference between the impedance Rx1 of the 1st transmission line sub-segment and the output impedance R PD of the signal output port S SPD of the photoelectric detector 211 can be close to zero or equal to zero, and the impedance Rx M ​​​The input impedance R of the corresponding RF input terminal of the RF transmission circuit 110 in The difference between them is close to zero or equal to zero.

[0088] Understandably, the impedance R of the first transmission line segment mentioned above... X1 With the signal output port S of photodetector 211 PD Output impedance R SPD A difference close to zero can mean that the difference is within ±ΔR. m1 Between. Where, ΔR m1 It can be equal to 0, or ΔR m1 It can also be a value that is not equal to 0, but rather a value that is close to zero, for example, ΔR. m1 The impedance can be 0.001, -0.01, 0.1, 0.2, 0.3, etc. Those skilled in the art will understand that by setting the impedance R of the first transmission line segment... X1 With the signal output port S of photodetector 211 PD Output impedance R SPD When the difference between them is close to or equal to zero, high bandwidth, high transmission coefficient, and low noise can be achieved. Therefore, in some embodiments, those skilled in the art can set ΔR according to the needs of the actual application scenario, while meeting this objective. m1 The specific value is not limited in this application.

[0089] Furthermore, the impedance Rx of the aforementioned Mth transmission line segment... M The input impedance R of the RF input terminal of the connected RF transmission circuit 110 in A difference close to zero can mean that the difference is within ±ΔR. m2 Between. Where, ΔR m2 It can be equal to 0, or ΔR m2 It can also be a value that is not equal to 0, but rather a value that is close to zero, for example, ΔR. m2 The impedance can be 0.001, -0.01, 0.1, 0.2, 0.3, etc. Those skilled in the art will understand that by setting the impedance Rx of the Mth transmission line segment... M The input impedance R of the RF input terminal of the connected RF transmission circuit 110 in When the difference between them is close to or equal to zero, high bandwidth, high transmission coefficient, and low noise can be achieved. Therefore, in some embodiments, those skilled in the art can set ΔR according to the needs of the actual application scenario, while meeting this objective. m2 The specific value of ΔR is not limited herein. m1 and ΔR m2 They can be the same or different, and can be determined according to the needs of the actual application scenario. No restrictions are imposed here.

[0090] In some embodiments, M can be greater than or equal to 4, i.e., the first ladder transfer plane transmission line 212 is divided into at least 4 segments, and the impedance variation of the 1st transmission line subsection to the Mth transmission line subsection is adjusted, for example, the impedance of each transmission line subsection from the 1st transmission line subsection to the Mth transmission line subsection can be sequentially reduced, increased, and then reduced again, so as to further improve the transmission coefficient on the basis of matching a large bandwidth. Exemplarily, since the 1st transmission line subsection is connected to the signal output port S PD In order to compensate for the impedance of the 1st transmission line subsection, the impedance of each transmission line subsection from the 1st transmission line subsection to the ath transmission line subsection connected in sequence can be sequentially reduced. Since the Mth transmission line subsection is connected to the corresponding radio frequency transmission circuit 110, in order to compensate for the impedance of the Mth transmission line subsection, the impedance of each transmission line subsection from the ath transmission line subsection to the bth transmission line subsection connected in sequence can be sequentially increased first, and increased to be greater than the impedance of the Mth transmission line subsection. Then, the impedance of each transmission line subsection from the bth transmission line subsection to the Mth transmission line subsection connected in sequence is sequentially reduced.

[0091] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (such as 2.4 GHz, 5 GHz), a can be set to 2, i.e., the impedance of the 2nd transmission line subsection is less than the impedance of the 1st transmission line subsection and the impedance of the 3rd transmission line subsection, or a can also be set to 3, i.e., the impedance of the 3rd transmission line subsection is less than the impedance of the 2nd transmission line subsection and the impedance of the 4th transmission line subsection, and the impedance of the 2nd transmission line subsection is less than the impedance of the 1st transmission line subsection. By setting in this way, the inflection point of the impedance increase can be set at the impedance of the 2nd transmission line subsection or the impedance of the 3rd transmission line subsection, which can further improve the transmission coefficient at certain frequency points.

[0092] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (such as 2.4 GHz, 5 GHz), b can be set to M-1, i.e., the impedance of the M-1th transmission line subsection is greater than the impedance of the Mth transmission line subsection and the impedance of the M-2th transmission line subsection, or b can also be set to M-2, i.e., the impedance of the M-2th transmission line subsection is greater than the impedance of the M-1th transmission line subsection and the impedance of the M-3th transmission line subsection, and the impedance of the M-1th transmission line subsection is greater than the impedance of the Mth transmission line subsection. By setting in this way, the inflection point of the impedance increase can be set at the impedance of the M-1th transmission line subsection or the impedance of the M-2th transmission line subsection, which can further improve the transmission coefficient at certain frequency points.

[0093] In some embodiments, the specific number of transmission line segments can be determined based on the requirements for impedance matching, high bandwidth, high transmission coefficient, and low noise, as well as considerations such as the size and cost of the receiving optical module 200. Those skilled in the art can choose an appropriate value; for example, the specific number of transmission line segments can be set to 3 to 20. In practical applications, if the number of transmission line segments is too small, the impedance variation trend of the transmission line segments will be ineffective. If the number of transmission line segments is too large, the size will be too large, losses will increase, and the design and manufacturing difficulty will increase, leading to increased costs. Therefore, considering both cost and performance, in some embodiments, 4 ≤ M ≤ 10 is set to balance the impact of cost and performance. For example, M can be 4, 6, 8, 9, 10, etc., and is not limited here.

[0094] In some embodiments, the first stepped-transformed planar transmission line 212 can be formed using a stepped-transformed microstrip line or a stepped-transformed stripline. For example, when the first stepped-transformed planar transmission line 212 is configured as a stepped-transformed microstrip line, the stepped-transformed microstrip line is divided into the first transmission line segment to the Mth transmission line segment. When the first stepped-transformed planar transmission line 212 is configured as a stepped-transformed stripline, the stepped-transformed stripline is divided into the first transmission line segment to the Mth transmission line segment.

[0095] The following example illustrates the structure of the first step-transformed plane transmission line 212 provided in this application embodiment, using a step-transformed microstrip line to form the first step-transformed plane transmission line 212.

[0096] Figure 3a A schematic diagram of the structure of the first step-conversion planar transmission line 212, the radio frequency transmission circuit 110, and the photodetector 211 provided in the embodiments of this application is shown below. Figure 3a The first step-transformation plane transmission line 212 may include a first transmission line segment Xa1 to a sixth transmission line segment Xa6 connected in sequence, wherein the first transmission line segment Xa1 is connected to the signal output port S of the photodetector 211. PD Electrical connections can be achieved using soldering or wire bonding (such as gold wire bonding). Transmission line segments Xa1 to Xa6 are connected in series, with Xa6 used to connect to the RF input terminal of the corresponding RF transmission circuit 110. Furthermore, the impedances of transmission line segments Xa1 to Xa6 can satisfy the following relationship: R... Xa2 <R Xa1 R Xa2 <R Xa3 R Xa3 <R Xa4 R Xa4 <R Xa5 R Xa5 >RXa6 . Wherein, R Xa1 represents the impedance of the 1st transmission line sub-section Xa1, R Xa2 represents the impedance of the 2nd transmission line sub-section Xa2, R Xa3 represents the impedance of the 3rd transmission line sub-section Xa3, R Xa4 represents the impedance of the 4th transmission line sub-section Xa4, R Xa5 represents the impedance of the 5th transmission line sub-section Xa5, R Xa6 represents the impedance of the 6th transmission line sub-section Xa6.

[0097] Figure 3b Another structural schematic diagram of the first ladder conversion planar transmission line 212, the radio frequency transmission circuit 110 and the photoelectric detector 211 provided by the embodiment of the present application is provided, referring to Figure 3b The first ladder conversion planar transmission line 212 can include the 1st transmission line sub-section Xb1 to the 6th transmission line sub-section Xb6 connected in sequence, wherein the 1st transmission line sub-section Xb1 is connected with the signal output port S PD The electrical connection can be realized by welding or wire bonding, the 1st transmission line sub-section Xb1 to the 6th transmission line sub-section Xb6 are connected in series in turn, and the 6th transmission line sub-section Xb6 is used to connect the radio frequency input end of the corresponding radio frequency transmission circuit 110. Moreover, the impedance of the 1st transmission line sub-section Xb1 to the 6th transmission line sub-section Xb6 can satisfy the following relationship: R Xb2 < R Xb1 , R Xb3 < R Xb2 , R Xb3 < R Xb4 , R Xb4 < R Xb5 , R Xb5 > R Xb6 . Wherein, R Xb1 represents the impedance of the 1st transmission line sub-section Xb1, R Xb2 represents the impedance of the 2nd transmission line sub-section Xb2, R Xb3 represents the impedance of the 3rd transmission line sub-section Xb3, R Xb4 represents the impedance of the 4th transmission line sub-section Xb4, R Xb5 represents the impedance of the 5th transmission line sub-section Xb5, R Xb6 represents the impedance of the 6th transmission line sub-section Xb6.

[0098] Figure 3c Another structural schematic diagram of the first ladder conversion planar transmission line 212, the radio frequency transmission circuit 110 and the photoelectric detector 211 provided by the embodiment of the present application is provided, referring to Figure 3cThe first ladder-transformed planar transmission line 212 can include the 1st transmission line subsection Xc1 to the 9th transmission line subsection Xc9 connected in sequence, wherein the 1st transmission line subsection Xc1 is connected to the signal output port S PD The electrical connection can be achieved by welding or wire bonding. The 1st transmission line subsection Xc1 to the 9th transmission line subsection Xc9 are connected in series in sequence, and the 9th transmission line subsection Xc9 is used to connect the radio frequency input end of the corresponding radio frequency transmission circuit 110. Moreover, the impedances of the 1st transmission line subsection Xc1 to the 9th transmission line subsection Xc9 can satisfy the following relationship: R Xc2 <R Xc1 , R Xc3 <R Xc2 , R Xc3 <R Xc4 , R Xc4 <R Xc5 , R Xc5 <R Xc6 , R Xc6 <R Xc7 , R Xc7 <R Xc8 , R Xc8 >R Xc9 . Wherein, R Xc1 represents the impedance of the 1st transmission line subsection Xc1, R Xc2 represents the impedance of the 2nd transmission line subsection Xc2, R Xc3 represents the impedance of the 3rd transmission line subsection Xc3, R Xc4 represents the impedance of the 4th transmission line subsection Xc4, R Xc5 represents the impedance of the 5th transmission line subsection Xc5, R Xc6 represents the impedance of the 6th transmission line subsection Xc6, R Xc7 represents the impedance of the 7th transmission line subsection Xc7, R Xc8 represents the impedance of the 8th transmission line subsection Xc8, and R Xc9 represents the impedance of the 9th transmission line subsection Xc9.

[0099] It can be understood that the above embodiments are only examples of the specific structure of the first ladder-transformed planar transmission line 212, and in specific implementation, the specific structure of the first ladder-transformed planar transmission line 212 is not limited to the above structure provided by the embodiments of the present application, but can also be other structures known by those skilled in the art based on the same concept, which is not limited here.

[0100] In some embodiments of the present application, the first stepped transformation planar transmission line 212 is integrated together with the photodetector 211 as an independent device (such as a PD chip) to form a receiving optical module 200, and the receiving optical module 200 is mounted or arranged on a circuit board (for example, a printed circuit board (PCB)) provided with a corresponding radio frequency transmission circuit, so that the receiving optical module 200 is electrically connected with the corresponding radio frequency transmission circuit. For example, referring to Figure 4 , Figure 4 A three-dimensional structure schematic diagram of the receiving optical module and the optical fiber provided in the embodiments of the present application is shown in FIG. 6. The receiving optical module 200 can include a housing 213, the housing 213 has an accommodation space 2131 inside, and a substrate (for example, an insulating substrate) is arranged in the accommodation space 2131, and the PD chip and the first stepped transformation planar transmission line 212 are arranged on the substrate. In the first direction F1, an optical fiber connection port is arranged on one surface of the housing 213, one side of the optical fiber connection port is connected with the PD optical coupling assembly, and the other side of the optical fiber connection port is used to connect one end of the optical fiber access assembly, and the other end of the optical fiber access assembly is connected with the optical fiber. In operation, the light of the optical fiber is coupled into the light receiving area of the PD chip through the PD optical coupling assembly, so as to perform photoelectric conversion through the PD chip and output a radio frequency signal. In the second direction F2, a power supply input port assembly, a radio frequency output port assembly and a ground input port assembly are arranged on one surface of the housing 213 at intervals, wherein the power supply input port assembly can serve as a power supply input port to input a direct current voltage, the radio frequency output port assembly can serve as the radio frequency output port to output the radio frequency signal to the second radio frequency transmission circuit 22, and the ground input port assembly can serve as a ground input port to realize grounding. In some embodiments, the power supply input port assembly, the radio frequency output port assembly and the ground input port assembly can be inserted into the circuit board to realize the conduction of the direct current voltage and the ground voltage and the transmission of the radio frequency signal. It can be understood that the first stepped transformation planar transmission line 212 can also be integrated in the PD chip to improve the integration and further realize miniaturization.

[0101] Since the PD chip has not only a signal output port but also a ground port, other components need to be arranged in the receiving optical module 200 to realize the overall function of the PD chip.

[0102] Figure 5a An equivalent circuit structure schematic diagram of the receiving optical module provided in the embodiments of the present application is shown in FIG. 7, Figure 5b An equivalent circuit structure schematic diagram of the receiving optical module provided in the embodiments of the present application is shown in FIG. 7, Figure 5a A corresponding specific structure schematic diagram is shown in FIG. 8, Figure 5a A corresponding specific structure schematic diagram is shown in FIG. 8, Figure 5b A corresponding specific structure schematic diagram is shown in FIG. 8, Figure 3aThe first ladder transformation plane transmission line 212 is shown, and the photoelectric detector is a GSG type PD chip. The receiving optical module 200 can include: a photoelectric detector 211 disposed on a substrate, a first ladder transformation plane transmission line 212, a first receiving component 310, a first receiving ground capacitor CP1, a second receiving component 320, and a third receiving ground capacitor CP3. The signal output port S PD The sixth transmission line sub-section Xa6 is connected with the radio frequency output port of the receiving optical module 200, and the radio frequency output port of the receiving optical module 200 is connected with a corresponding radio frequency transmission circuit. The first end of the first receiving component 310 is connected with one of the first transmission line sub-section Xa1 to the Mth transmission line sub-section, and the second end of the first receiving component 310 is used for connecting the ground input port. The first electrode of the first receiving ground capacitor CP1 is connected with the first ground port G PD1 of the photoelectric detector 211, and the second electrode of the first receiving ground capacitor CP1 is used for connecting the ground input port. The first end of the second receiving component 320 is connected with the first ground port G PD1 of the photoelectric detector 211, and the second end of the second receiving component 320 is used for connecting the power supply input port. The first electrode of the third receiving ground capacitor CP3 is connected with the second ground port G PD2 of the photoelectric detector 211, and the second electrode of the third receiving ground capacitor CP3 is used for connecting the ground input port, so that the second ground port G PD2 of the photoelectric detector 211 is grounded through the third receiving ground capacitor CP3. By means of the above arrangement, the receiving optical module can be realized by using simple devices, and the transmission loss of the radio frequency signal can be reduced, and the cost can be reduced.

[0103] The first receiving component 310 is used for coupling the signal of the ground input port to the transmission line sub-section connected therewith, so that the ground voltage input by the ground input port can be input to the signal output port S PD of the photoelectric detector 211. Moreover, since the signal output port S PD of the photoelectric detector 211 is used for outputting the radio frequency signal, in order to avoid the radio frequency signal from leaking to the ground, the first receiving component 310 can also be used for blocking the radio frequency signal, so that the radio frequency signal can enter the corresponding radio frequency transmission circuit through the first ladder transformation plane transmission line 212 as much as possible. Further, in order to reduce the influence of the first receiving component 310 on the impedance of each transmission line sub-section in the first ladder transformation plane transmission line 212 and the radio frequency signal leakage, the first end of the first receiving component 310 can be connected to the connection between the first transmission line sub-section and the second transmission line sub-section.

[0104] Exemplarily, with reference to Figure 5bThe first receiving component 310 can include a first quarter wavelength transmission line 311. Alternatively, the first receiving component 310 can also include a first receiving inductor. With the above arrangement, a simple device can be used to achieve both transmission of voltage and blocking or reducing of RF signal. Of course, in actual applications, the first receiving component 310 can also be configured as other devices that can achieve the above functions, which are not limited herein. In addition, the first receiving component 310 is configured to achieve two purposes, one is to transmit the ground voltage, and the other is to block the RF signal. However, in actual applications, a small amount of RF signal can leak to the ground through the first receiving component 310, but the leakage is usually not too much, and the influence on the transmission coefficient and noise is small and can be ignored.

[0105] The second receiving component 320 and the first receiving ground capacitor CP1 are respectively used to couple the signal of the power supply input port to the first ground port G PD1 , so that the DC voltage input by the power supply input port can be input to the first ground port G PD1 of the photodetector 211. In addition, in order to avoid the RF signal generated by the photodetector 211 from leaking to the power supply input port, the second receiving component 320 can be used to block the RF signal, so that the RF signal can be transmitted into the corresponding RF transmission circuit through the first stepped transformation plane transmission line 212 as much as possible. For example, referring to Figure 5a and Figure 5b , the second receiving component 320 can include a second receiving inductor LP2. With the above arrangement, a simple device can be used to achieve both transmission of ground voltage and blocking or reducing of RF signal. Of course, in actual applications, the second receiving component 320 can also be configured as other devices that can achieve the above functions, for example, a second quarter wavelength transmission line, which are not limited herein. In addition, the second receiving component 320 is configured to transmit the ground voltage and block or reduce the RF signal. In actual applications, a small amount of RF signal can leak to the DC voltage end through the second receiving component 320, but the leaked RF signal is usually weak, and the influence on the transmission coefficient and noise is small and can be ignored.

[0106] For example, referring to Figure 5b, the photoelectric detector 211 and the first stepped transformation planar transmission line 212 are arranged on one side of the substrate, the other side of the substrate is entirely coated with a ground conductive layer (for example, a metal layer), and the ground conductive layer is connected to a ground input port assembly. The sixth transmission line subsegment of the first stepped transformation planar transmission line 212 is connected to a radio frequency output port assembly. In order to reduce signal interference, a metal shielding layer 411 can be arranged between the photoelectric detector 211 and the substrate, the metal shielding layer 411 is connected to the ground conductive layer through a plurality of vias AX1 penetrating the substrate to realize grounding. The metal shielding layer can also serve as the second electrode of the first receiving ground capacitor CP1 and the second electrode of the third receiving ground capacitor CP3. Alternatively, the second electrode of the first receiving ground capacitor CP1 and the second electrode of the third receiving ground capacitor CP3 can also be connected to the metal shielding layer by welding or other connection methods. In addition, the first end of the first quarter wavelength transmission line 311 is connected to the junction between the first transmission line subsegment Xa1 and the second transmission line subsegment Xa2. The side of the substrate provided with the photoelectric detector 211 is also provided with a ground wire 412, the second end of the first quarter wavelength transmission line is connected to the ground wire 412, and the ground wire 412 is connected to the ground conductive layer through a plurality of vias AX2 penetrating the substrate to realize grounding. The side of the substrate provided with the photoelectric detector 211 is also provided with a switching wire 413, the first electrode of the first receiving ground capacitor CP1 is connected to the switching wire 413 by wire bonding (for example, gold wire bonding), and the first end of the second receiving inductor is also connected to the switching wire 413 by wire bonding (for example, gold wire bonding), to realize the mutual connection between the first electrode of the first receiving ground capacitor CP1, the first end of the second receiving inductor, and the first ground port G PD1 of the photoelectric detector 211. In addition, the side of the substrate provided with the photoelectric detector 211 is also provided with a power supply transmission line 414, the second end of the second receiving inductor is connected to the power supply transmission line 414 by wire bonding (for example, gold wire bonding), and the power supply transmission line 414 is connected to a power supply input port assembly to realize direct current voltage input. It is worth mentioning that, Figure 5b The above is only an example to illustrate the specific structure that can be achieved by the photoelectric detector 211 and the first stepped transformation planar transmission line 212, and in specific implementation, the specific structure is not limited to the above structure provided in the embodiments of the present application, but can also be other structures known by those skilled in the art based on the same concept, which is not limited here.

[0107] Figure 6 Another equivalent circuit structure schematic diagram of a receiving optical module provided in the embodiments of the present application is shown in FIG. 8. Referring to Figure 6 , the present embodiment is directed to Figure 5aThe shown embodiment is deformed, and the same parts are not repeated here, and the different parts are that: the receiving optical module 200 includes: a photodetector 211, a first stepped transformation plane transmission line 212, a first receiving component 310, a second receiving ground capacitor CP2, and a third receiving ground capacitor CP3, the signal output port S PD The sixth transmission line sub-section Xa6 is connected with the radio frequency output port of the receiving optical module 200, and the radio frequency output port of the receiving optical module 200 is connected with the corresponding radio frequency transmission circuit. The first end of the first receiving component 310 is connected with one of the first transmission line sub-section to the Mth transmission line sub-section, and the second end of the first receiving component 310 is used for connecting the power supply input port. The first electrode of the second receiving ground capacitor CP2 is connected with the first ground port G PD1 of the photodetector 211, and the second electrode of the second receiving ground capacitor CP2 is used for connecting the ground input port, so that the first ground port G PD1 of the photodetector 211 is grounded through the second receiving ground capacitor CP2. The first electrode of the third receiving ground capacitor CP3 is connected with the second ground port G PD2 of the photodetector 211, and the second electrode of the third receiving ground capacitor CP3 is used for connecting the ground input port, so that the second ground port G PD2 of the photodetector 211 is grounded through the third receiving ground capacitor CP3. According to the embodiment, the receiving optical module can be realized by simple devices, and the transmission loss and cost of the radio frequency signal can be reduced.

[0108] Exemplarily, the first receiving component 310 can also be set as a first receiving inductor LP1, which can not only transmit the ground voltage, but also block the radio frequency signal. Alternatively, the first receiving component 310 can be set as a first quarter wavelength transmission line.

[0109] In order to stabilize the direct current voltage, a sixth receiving ground capacitor CP6 can also be arranged in the receiving optical module 200, the first electrode of the sixth receiving ground capacitor CP6 is connected with the first end of the first receiving inductor, and the second electrode of the sixth receiving ground capacitor CP6 is used for connecting the ground input port. Of course, in some embodiments of the present application, the performance of the receiving optical module 200 meets the requirements, and the sixth receiving ground capacitor CP6 can also be removed to reduce the number of capacitor devices.

[0110] In some embodiments, Figure 6 The corresponding specific structure diagram can be designed with reference to Figure 5b , and the details are not repeated here.

[0111] In some embodiments of this application, in addition to using a first-step transformed plane transmission line for impedance matching, a lumped element network formed by capacitors and inductors can also be used for impedance matching. For example, Figure 7 This is a schematic diagram of another equivalent circuit structure of the receiving optical module provided in the embodiments of this application, referring to... Figure 7 This embodiment is for Figure 5a The illustrated embodiment has been modified, and the similarities will not be repeated here. The difference is that the receiving optical module 200 includes a photodetector 211 and a first lumped element network 214, wherein the first end of the first lumped element network 214 is connected to the signal output port S of the photodetector 211. PD The second terminal of the first lumped element network 214 is connected to the RF input terminal of the corresponding RF transmission circuit for impedance matching. To reduce losses, the first lumped element network 214 includes multiple receiver matching capacitors (e.g., Cm1 to Cm3) and multiple receiver matching inductors (e.g., Lm1 to Lm2), and these multiple receiver matching inductors are connected in series to the signal output port S of the photodetector 211. PD Between the RF input terminal of the RF transmission circuit and the receiver matching inductor, at least two ends of a receiver matching capacitor are connected one-to-one, and the second ends of multiple receiver matching capacitors are used to connect to the ground input port. Therefore, impedance matching can be achieved using capacitors and inductors instead of resistors, reducing losses during RF signal transmission.

[0112] In some embodiments of this application, a photodetector circuit model related to the input optical power, bias voltage, and frequency can be established based on measured DC and scattering (S-S) parameter data at different input optical powers, bias voltages, and frequencies to accurately characterize the photoelectric conversion process of the photodetector 211. The photodetector circuit model can include three regions: a DC parameter region, a chip intrinsic region, and a parasitic parameter region. The DC parameter region includes a voltage-controlled current source and a diode connected in parallel, to characterize the DC parameter characteristics of the photodetector. The chip intrinsic region includes a third capacitor and a third resistor, to characterize the junction capacitance of the photodetector (the junction capacitance is a variable capacitance and is related to the bias voltage and optical power) using the third capacitor, and the drift resistance of the photodetector (the drift resistance is a variable resistance and is related to the bias voltage and optical power) using the third resistor. The parasitic parameter region includes a fourth capacitor, a fourth resistor, and a second inductor, with the fourth resistor representing the parasitic resistance of the photodetector, the second inductor representing the parasitic inductance of the photodetector, and the fourth capacitor representing the parasitic capacitance of the photodetector.

[0113] Based on the established photoelectric detector circuit model, and based on the requirements of matching a large bandwidth (for example, 10GHz-13GHz) and a transmission coefficient greater than or equal to 0.9, simulation is performed to obtain the number of capacitors and inductors that meet the above requirements, as well as the variation law of the capacitance value of the capacitor and the inductance value of the inductor. Among them, in the direction from the signal output port S PD In the direction from the signal output port of the photoelectric detector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the plurality of receiving matching inductors (for example, Lm1-Lm2) have a decreasing trend, and the capacitance values of the plurality of receiving matching capacitors (for example, Cm1-Cm3) have a decreasing trend. Based on this, the capacitors and inductors in the first lumped element network 214 are designed to achieve impedance matching, which can minimize the loss of the radio frequency signal in the output process, effectively reduce the loss of the radio frequency signal in the output process compared to using a resistor for impedance matching, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and thus obtaining a high-performance RoF transmission link.

[0114] In some embodiments of the present application, in the direction from the signal output port of the photoelectric detector to the radio frequency input end of the radio frequency transmission circuit, the difference in inductance value of each adjacent receiving matching inductor in the partially or entirely sequentially connected receiving matching inductors can be the same. For example, taking four sequentially connected receiving matching inductors as an example, in the direction from the signal output port of the photoelectric detector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching inductors are named as: a first receiving matching inductor, a second receiving matching inductor, a third receiving matching inductor, and a fourth receiving matching inductor, wherein the inductance value of the first receiving matching inductor is greater than the inductance value of the second receiving matching inductor, the inductance value of the second receiving matching inductor is greater than the inductance value of the third receiving matching inductor, and the inductance value of the third receiving matching inductor is greater than the inductance value of the fourth receiving matching inductor. Moreover, the difference in inductance value between the first receiving matching inductor and the second receiving matching inductor is ΔL11, the difference in inductance value between the second receiving matching inductor and the third receiving matching inductor is ΔL21, and the difference in inductance value between the third receiving matching inductor and the fourth receiving matching inductor is ΔL31, ΔL11=ΔL21=ΔL31. Thus, the inductance value of the receiving matching inductor can be made to decrease in an arithmetic progression in the direction from the signal output port of the photoelectric detector to the radio frequency input end of the radio frequency transmission circuit. In addition, the present application does not limit the specific values of ΔL11, ΔL21, and ΔL31, which can be determined according to the requirements of the actual application scenario.

[0115] In some embodiments of the present application, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the sequentially connected partial or all receiving matching inductors decrease in turn. For example, taking four sequentially connected receiving matching inductors as an example, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching inductors are named as a first receiving matching inductor, a second receiving matching inductor, a third receiving matching inductor and a fourth receiving matching inductor, wherein the inductance value of the first receiving matching inductor is greater than the inductance value of the second receiving matching inductor, the inductance value of the second receiving matching inductor is greater than the inductance value of the third receiving matching inductor, and the inductance value of the third receiving matching inductor is greater than the inductance value of the fourth receiving matching inductor. Moreover, the inductance value difference between the first receiving matching inductor and the second receiving matching inductor is ΔL12, the inductance value difference between the second receiving matching inductor and the third receiving matching inductor is ΔL22, and the inductance value difference between the third receiving matching inductor and the fourth receiving matching inductor is ΔL32, ΔL12>ΔL22>ΔL32. Thus, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the receiving matching inductors decrease based on the inductance value differences decreasing in turn. Moreover, the present application does not limit the specific values of ΔL12, ΔL22 and ΔL32, which can be determined according to the requirements of actual application scenarios.

[0116] In some embodiments of the present application, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the sequentially connected partial or all receiving matching inductors can also be arranged to increase in turn. For example, taking four sequentially connected receiving matching inductors as an example, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching inductors are named as a first receiving matching inductor, a second receiving matching inductor, a third receiving matching inductor and a fourth receiving matching inductor, wherein the inductance value of the first receiving matching inductor is greater than the inductance value of the second receiving matching inductor, the inductance value of the second receiving matching inductor is greater than the inductance value of the third receiving matching inductor, and the inductance value of the third receiving matching inductor is greater than the inductance value of the fourth receiving matching inductor. Moreover, the inductance value difference between the first receiving matching inductor and the second receiving matching inductor is ΔL13, the inductance value difference between the second receiving matching inductor and the third receiving matching inductor is ΔL23, and the inductance value difference between the third receiving matching inductor and the fourth receiving matching inductor is ΔL33, ΔL13<ΔL23<ΔL33. Thus, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the receiving matching inductors can be arranged to decrease based on the increasing difference. In addition, the present application does not limit the specific values of ΔL13, ΔL23 and ΔL33, which can be determined according to the requirements of the actual application scenario.

[0117] It can be understood that the above is only an example to illustrate some embodiments in which the inductance values of the receiving matching inductors decrease in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit. In other embodiments, other rules can also be used to realize the embodiments in which the inductance values of the receiving matching inductors decrease, as long as the above-mentioned inductance values of the receiving matching inductors decrease are met, which belong to the protection scope of the present application, and the specific embodiments are not limited herein.

[0118] In some embodiments of the present application, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the difference between the capacitance values of each adjacent receiving matching capacitor in the sequentially connected partial or all receiving matching capacitors is the same. For example, taking four sequentially connected receiving matching capacitors as an example, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching capacitors are named as: the first receiving matching capacitor, the second receiving matching capacitor, the third receiving matching capacitor and the fourth receiving matching capacitor, wherein the capacitance value of the first receiving matching capacitor is greater than the capacitance value of the second receiving matching capacitor, the capacitance value of the second receiving matching capacitor is greater than the capacitance value of the third receiving matching capacitor, and the capacitance value of the third receiving matching capacitor is greater than the capacitance value of the fourth receiving matching capacitor. Moreover, the difference between the capacitance values of the first receiving matching capacitor and the second receiving matching capacitor is ΔC11, the difference between the capacitance values of the second receiving matching capacitor and the third receiving matching capacitor is ΔC21, and the difference between the capacitance values of the third receiving matching capacitor and the fourth receiving matching capacitor is ΔC31, ΔC11 = ΔC21 = ΔC31. Thus, the difference between the capacitance values of the receiving matching capacitors can be reduced in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit. In addition, the present application does not limit the specific values of ΔC11, ΔC21 and ΔC31, which can be determined according to the requirements of the actual application scenario.

[0119] In some embodiments of the present application, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the capacitance values of the sequentially connected partial or all receiving matching capacitors decrease in turn. For example, taking four sequentially connected receiving matching capacitors as an example, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching capacitors are named as a first receiving matching capacitor, a second receiving matching capacitor, a third receiving matching capacitor and a fourth receiving matching capacitor, wherein the capacitance value of the first receiving matching capacitor is greater than that of the second receiving matching capacitor, the capacitance value of the second receiving matching capacitor is greater than that of the third receiving matching capacitor, and the capacitance value of the third receiving matching capacitor is greater than that of the fourth receiving matching capacitor. Moreover, the capacitance value difference between the first receiving matching capacitor and the second receiving matching capacitor is ΔC12, the capacitance value difference between the second receiving matching capacitor and the third receiving matching capacitor is ΔC22, and the capacitance value difference between the third receiving matching capacitor and the fourth receiving matching capacitor is ΔC32, and ΔC12>ΔC22>ΔC32. Thus, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the capacitance values of the receiving matching capacitors decrease based on the decreasing differences in turn. In addition, the present application does not limit the specific values of ΔC12, ΔC22 and ΔC32, which can be determined according to the requirements of the actual application scenario.

[0120] In some embodiments of the present application, the capacitance values of the sequentially connected partial or all receiving matching capacitors can be sequentially increased in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit. For example, taking four sequentially connected receiving matching capacitors as an example, in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the four receiving matching capacitors are named as a first receiving matching capacitor, a second receiving matching capacitor, a third receiving matching capacitor and a fourth receiving matching capacitor, wherein the capacitance value of the first receiving matching capacitor is greater than the capacitance value of the second receiving matching capacitor, the capacitance value of the second receiving matching capacitor is greater than the capacitance value of the third receiving matching capacitor, and the capacitance value of the third receiving matching capacitor is greater than the capacitance value of the fourth receiving matching capacitor. In addition, the capacitance value difference between the first receiving matching capacitor and the second receiving matching capacitor is ΔC13, the capacitance value difference between the second receiving matching capacitor and the third receiving matching capacitor is ΔC23, and the capacitance value difference between the third receiving matching capacitor and the fourth receiving matching capacitor is ΔC33, ΔC13<ΔC23<ΔC33. Thus, the capacitance values of the receiving matching capacitors can be sequentially decreased in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit. In addition, the specific values of ΔC13, ΔC23 and ΔC33 are not limited in the present application, which can be determined according to the requirements of the actual application scene.

[0121] It can be understood that the above is only an example to illustrate some embodiments in which the capacitance values of the receiving matching capacitors decrease in the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit. In other embodiments, other rules can be used to realize the embodiments in which the capacitance values of the receiving matching capacitors decrease, as long as the above-mentioned trend of the capacitance values of the receiving matching capacitors is met, which belongs to the protection scope of the present application, and the specific embodiments are not limited herein.

[0122] As an example, referring to Figure 7 , the plurality of receiving matching inductors includes a first receiving matching inductor Lm1 and a second receiving matching inductor Lm2, and the plurality of receiving matching capacitors includes a first receiving matching capacitor Cm1, a second receiving matching capacitor Cm2 and a third receiving matching capacitor Cm3. Wherein, the first end of the first receiving matching inductor Lm1 is connected to the first end of the first receiving matching capacitor Cm1 and the signal output port S PDThe second end of the first receiving matching inductor Lm1 is connected with the first end of the second receiving matching inductor Lm2 and the first end of the second receiving matching capacitor Cm2 respectively, the second end of the second receiving matching inductor Lm2 is connected with the first end of the third receiving matching capacitor Cm3 and the radio frequency output port respectively, and the second end of the first receiving matching capacitor Cm1, the second end of the second receiving matching capacitor Cm2 and the second end of the third receiving matching capacitor Cm3 are all connected to the ground input port. Thus, the first lumped element network can be realized by using a simple structure to realize impedance matching. In addition, the radio frequency output port is used for connecting to the radio frequency input port of the radio frequency transmission circuit.

[0123] The inductance value of the first receiving matching inductor Lm1 is greater than the inductance value of the second receiving matching inductor Lm2. The capacitance value of the first receiving matching capacitor Cm1 is greater than the capacitance value of the second receiving matching capacitor Cm2, and the capacitance value of the second receiving matching capacitor Cm2 is greater than the capacitance value of the third receiving matching capacitor Cm3. Exemplarily, the difference between the capacitance value of the first receiving matching capacitor Cm1 and the capacitance value of the second receiving matching capacitor Cm2 is Δ1, and the difference between the capacitance value of the second receiving matching capacitor Cm2 and the capacitance value of the third receiving matching capacitor Cm3 is Δ2, Δ1 can be equal to Δ2, or Δ1 can be greater than Δ2, or Δ1 can be less than Δ2, which is not limited herein. It can be understood that the example is only used to illustrate the specific structure of the first lumped element network 214, and the specific structure of the first lumped element network 214 is not limited to the above structure provided by the embodiment of the present application, and can also be other structures known by those skilled in the art based on the same concept, which is not limited herein.

[0124] In some embodiments, Figure 7 The receiving optical module 200 can further include a third receiving inductor LP3, the first end of the third receiving inductor LP3 is connected with the signal output port S PD The second end of the third receiving inductor LP3 is connected with the power supply input port. Thus, the direct current voltage of the power supply input port can be coupled to the signal output port S PD of the photodetector 211 through the third receiving inductor LP3. In some embodiments, the third receiving inductor LP3 can also block or reduce the amount of radio frequency signals passing through, so that the radio frequency signals can enter the corresponding radio frequency transmission circuit through the first lumped element network 214 as much as possible. In actual application, a small amount of radio frequency signals can leak through the third receiving inductor LP3, but the amount of the leaked radio frequency signals is weak, and the influence of the weak radio frequency signals on the transmission coefficient and noise is small and can be ignored. PD The power supply input port is connected with the power supply output port. In some embodiments, the third receiving inductor LP3 can also block or reduce the amount of radio frequency signals passing through, so that the radio frequency signals can enter the corresponding radio frequency transmission circuit through the first lumped element network 214 as much as possible. In actual application, a small amount of radio frequency signals can leak through the third receiving inductor LP3, but the amount of the leaked radio frequency signals is weak, and the influence of the weak radio frequency signals on the transmission coefficient and noise is small and can be ignored.

[0125] In some embodiments, Figure 7The receiving optical module 200 can further include a fourth receiving ground capacitor CP4, a first electrode of the fourth receiving ground capacitor CP4 being connected with the first ground port G PD1 A second electrode of the fourth receiving ground capacitor CP4 is used for connecting the ground input port. In this way, the first ground port G PD1 is grounded through the fourth receiving ground capacitor CP4. In some embodiments, the fourth receiving ground capacitor CP4 can also block or reduce the amount of radio frequency signals passing through. In actual applications, there can be a small amount of radio frequency signals leaking through the fourth receiving ground capacitor CP4, but the amount of the leaked radio frequency signals is usually small, and the weak leaked radio frequency signals have little effect on the transmission coefficient and noise, which can be ignored.

[0126] In some embodiments, Figure 7 The receiving optical module 200 further includes a fifth receiving ground capacitor CP5, a first electrode of the fifth receiving ground capacitor CP5 being connected with the second ground port G PD2 A second electrode of the fifth receiving ground capacitor CP5 is used for connecting the ground input port. In this way, the second ground port G PD2 is grounded through the fifth receiving ground capacitor CP5. In some embodiments, the fifth receiving ground capacitor CP5 can also block or reduce the amount of radio frequency signals passing through. In actual applications, there can be a small amount of radio frequency signals leaking through the fifth receiving ground capacitor CP5, but the amount of the leaked radio frequency signals is usually small, and the weak leaked radio frequency signals have little effect on the transmission coefficient and noise, which can be ignored.

[0127] The present application also takes the output impedance of the photodetector 211 as 15+j19.7 ohms, and the input impedance of the connected radio frequency transmission circuit as 50 ohms as an example, and simulates the structure shown in Figure 7 , and for the impedance matching requirement of the 4.5GHz frequency point, by setting the inductance value of the first receiving matching inductor Lm1 as 0.61nH, the inductance value of the second receiving matching inductor Lm2 as 0.56nH, the capacitance value of the first receiving matching capacitor Cm1 as 1.2pF, the capacitance value of the second receiving matching capacitor Cm2 as 0.3pF, and the capacitance value of the third receiving matching capacitor Cm3 as 0.22pF, the transmission coefficient of the radio frequency signal in the transmission process can be greater than 0.95, so that the loss of the radio frequency signal in the transmission process can be reduced as much as possible.

[0128] In some embodiments, Figure 7 The corresponding specific structure diagram can be designed with reference to Figure 5b , and specific details are not described here.

[0129] In summary, the embodiment of the present application reduces the loss of the radio frequency signal in the output process in the optical receiving module by using the first ladder conversion plane transmission line or the first lumped element network as the impedance matching device in the optical receiving module. Similarly, in the transmitting optical module, the problem of using resistance for impedance matching and causing the power of the radio frequency signal to be damaged also exists. The structure of the transmitting optical module provided by the embodiment of the present application is described in detail in combination with specific embodiments. It can be understood that the following embodiments are only used to illustrate the specific structure of the transmitting optical module, and the specific structure of the transmitting optical module is not limited to the following structure provided by the embodiment of the present application, but can also be other structures known by those skilled in the art based on the same concept, which is not limited here.

[0130] Figure 8 The structure block diagram of the transmitting optical module provided by the embodiment of the present application is shown in FIG. 5. Figure 8 The transmitting optical module 500 provided by the embodiment of the present application can include a direct modulation laser 511 and a second ladder conversion plane transmission line 512. The radio frequency output end of the corresponding radio frequency transmission circuit 120 is connected to the signal input port S LD of the direct modulation laser 511 through the second ladder conversion plane transmission line 512 for impedance matching. The radio frequency output end of the corresponding radio frequency transmission circuit 120 outputs the radio frequency signal, which is output to the signal input port S LD of the direct modulation laser 511 through the second ladder conversion plane transmission line 512. The direct modulation laser 511 converts the radio frequency signal into an optical signal through photoelectric conversion and outputs the optical signal. The direct modulation laser involved in the present application can include a direct modulation semiconductor laser (laser diode, LD).

[0131] In some embodiments of this application, a directly modulated laser circuit model related to the bias voltage, frequency, and output optical power can be established based on measured DC current (I)-voltage (V) data, scattering (S) parameter data, and different output optical powers at different bias voltages and frequencies, accurately characterizing the electro-optical conversion process of the directly modulated laser. The directly modulated laser circuit model can include three regions: a DC parameter region, a chip intrinsic region, and a parasitic parameter region. The DC parameter region includes current sources to characterize the DC parameter characteristics of the directly modulated laser. The chip intrinsic region includes a fifth capacitor and a fifth resistor, with the fifth capacitor characterizing the junction capacitance of the directly modulated laser (the junction capacitance is a variable capacitance and is related to the bias voltage), and the fifth resistor characterizing the drift resistance of the directly modulated laser (the drift resistance is a variable resistance and is related to the bias voltage). The parasitic parameter region includes a sixth capacitor, a sixth resistor, and a third inductor, with the sixth resistor representing the parasitic resistance of the directly modulated laser, the third inductor representing the parasitic inductance of the directly modulated laser, and the sixth capacitor representing the parasitic capacitance of the directly modulated laser.

[0132] Using an established laser circuit model, and based on the requirements of a large matching bandwidth (e.g., 2GHz to 6GHz) and a transmission coefficient greater than or equal to 0.9, simulations were performed to obtain a second-order transform plane transmission line that meets the above requirements. This involves segmenting the second-order transform plane transmission line and designing adjacent segments with different impedances. Designing the second-order transform plane transmission line based on this impedance matching minimizes the loss of RF signals during output. Compared to impedance matching using resistors, this effectively reduces RF signal loss during output, thereby improving the gain of the entire RoF network system, reducing the noise figure, and ultimately achieving a high-performance RoF transmission link.

[0133] In some embodiments, the second step-transformation planar transmission line 512 may include sequentially connected first to Nth transmission line segments. The first transmission line segment is used to connect to the RF output terminal of the corresponding RF transmission circuit 120, and the Nth transmission line segment is connected to the signal input port S of the direct-modulated laser 511. LD Connection. In some examples, the transmitting optical module 500 of this application can be applied to... Figure 1a and Figure 1b In the scenario shown, the central communication device 10 can be connected to the first radio frequency transmission circuit 120 via the first transmission line segment, which can be the first radio frequency transmission circuit 12. In other examples, the receiving optical module 200 of this application can be applied to… Figure 1b In the scenario shown, the remote communication device 20 can be connected to the radio frequency transmission circuit 120 of the first transmission line segment, which can be the second radio frequency transmission circuit 22.

[0134] And N can be an integer and N≥3, i.e. the second ladder transformation plane transmission line 512 is divided into at least 3 segments. In order to match the impedance, and meet the requirements of matching a large bandwidth (e.g. 2GHz-6GHz) and a transmission coefficient greater than or equal to 0.9, the impedance of at least one of the second transmission line segment to the N-1 transmission line segment can be less than the impedance of the N transmission line segment. Through simulation, it is found that if the impedance of the first transmission line segment to the N transmission line segment is set to decrease in a decreasing trend from large to small, impedance matching can also be achieved, but when using this impedance variation trend for impedance matching, the bandwidth is usually less than 0.5GHz, resulting in a narrow matching bandwidth and a greatly limited application range.

[0135] In order to match a larger bandwidth and improve the transmission coefficient, the impedance R Y1 of the first transmission line segment can be close to or equal to the output impedance R ot of the radio frequency output end of the radio frequency transmission circuit 120 connected thereto, and the impedance R YN of the N transmission line segment can be close to or equal to the input impedance R LD of the signal input port S SLD of the direct modulation laser 511.

[0136] It can be understood that the close to or equal to between the impedance R Y1 of the first transmission line segment and the output impedance R ot of the radio frequency output end of the radio frequency transmission circuit 120 connected thereto means that the difference can be between ±ΔR n1 . Wherein, ΔR n1 may be equal to 0, or ΔR n1 may not be equal to 0, but a value close to zero, for example, ΔR n1 may be 0.001, -0.01, 0.1, 0.2, 0.3, etc. Those skilled in the art can understand that by setting the difference between the impedance R Y1 of the first transmission line segment and the output impedance R ot of the radio frequency output end of the radio frequency transmission circuit 120 connected thereto to be close to or equal to zero, a large bandwidth, a high transmission coefficient, and a low noise can be achieved. Therefore, in some embodiments, those skilled in the art can set the specific value of ΔR n1 according to the requirements of the actual application scene on the premise of meeting the purpose, which is not limited in this application.

[0137] And the difference between the impedance R YN of the N transmission line segment and the input impedance R SLD of the signal input port of the direct modulation laser can be close to zero, which means that the difference can be between ±ΔRn2 ΔR n2 may be equal to 0, or ΔR n2 may not be equal to 0, but a value close to 0, for example, ΔR n2 may be 0.001, -0.01, 0.1, 0.2, 0.3, etc. Those skilled in the art can understand that when the difference between the impedance R YN of the Nth transmission line subsection and the input impedance R SLD of the signal input port of the direct modulation laser is close to 0 or equal to 0, a large bandwidth, a high transmission coefficient, and a low noise can be achieved. Therefore, in some embodiments, those skilled in the art can set the specific value of ΔR n2 according to the requirements of the actual application scenario on the premise of meeting the purpose, which is not limited herein. In addition, ΔR n1 and ΔR n2 may be the same or different, which can be determined according to the requirements of the actual application scenario, which is not limited herein.

[0138] In some embodiments, N≥5, that is, the second stepped transformation plane transmission line 512 is divided into at least 5 sections, and the impedance variation law of the 1st transmission line subsection to the Nth transmission line subsection is adjusted, for example, the impedance of each transmission line subsection in the 1st transmission line subsection to the Nth transmission line subsection can be sequentially increased, decreased, increased again, and decreased again, so as to further improve the transmission coefficient on the basis of matching a large bandwidth. Exemplarily, since the 1st transmission line subsection is connected to the corresponding radio frequency transmission circuit 120, in order to compensate for the impedance of the 1st transmission line subsection, the impedance of each transmission line subsection in the 1st transmission line subsection to the cth transmission line subsection connected in sequence can be sequentially increased. Since the Nth transmission line subsection is connected to the signal input port S LD of the direct modulation laser 511, in order to compensate for the impedance of the Nth transmission line subsection, the impedance of each transmission line subsection in the cth transmission line subsection to the dth transmission line subsection connected in sequence can be sequentially decreased, and the impedance of the dth transmission line subsection is decreased to be less than the input impedance R SLD of the direct modulation laser 511. Then, the impedance of each transmission line subsection in the dth transmission line subsection to the e th transmission line subsection connected in sequence can be sequentially increased, and the impedance of the e th transmission line subsection is increased to be greater than the input impedance R SLD of the direct modulation laser 511. Then, the impedance of each transmission line subsection in the e th transmission line subsection to the Nth transmission line subsection connected in sequence can be sequentially decreased.

[0139] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (e.g. 2.4 GHz, 5 GHz), c can be set to 2, i.e. the impedance of the second transmission line sub-section is greater than the impedance of the first transmission line sub-section and the impedance of the third transmission line sub-section, or c can also be set to 3, i.e. the impedance of the third transmission line sub-section is greater than the impedance of the second transmission line sub-section and the impedance of the fourth transmission line sub-section, and the impedance of the second transmission line sub-section is greater than the impedance of the first transmission line sub-section. With such settings, the inflection point of the first increase in impedance can be set at the impedance of the second transmission line sub-section or the impedance of the third transmission line sub-section, which can further improve the transmission coefficient at certain frequency points.

[0140] In some embodiments, in order to obtain a larger transmission coefficient at certain frequency points (e.g. 2.4 GHz, 5 GHz), e can be set to N-1, i.e. the impedance of the N-1th transmission line sub-section is greater than the impedance of the Nth transmission line sub-section and the impedance of the N-2th transmission line sub-section, and the impedance of the N-2th transmission line sub-section is less than the impedance of the Nth transmission line sub-section and the impedance of the N-3th transmission line sub-section, or e can also be set to N-2, i.e. the impedance of the N-2th transmission line sub-section is greater than the impedance of the N-1th transmission line sub-section and the impedance of the N-3th transmission line sub-section, and the impedance of the N-1th transmission line sub-section is greater than the impedance of the Nth transmission line sub-section, and the impedance of the N-3th transmission line sub-section is less than the impedance of the Nth transmission line sub-section and the impedance of the N-4th transmission line sub-section. With such settings, the inflection point of the second increase in impedance can be set at the impedance of the N-1th transmission line sub-section or the impedance of the N-2th transmission line sub-section, which can further improve the transmission coefficient at certain frequency points.

[0141] In some embodiments, for a specific number of transmission line sub-sections, a person skilled in the art can select a suitable value based on the needs of performance such as impedance matching, large bandwidth, high transmission coefficient, and low noise, as well as considerations such as the size and cost of the light emitting module 500. For example, the specific number of transmission line sub-sections can be set to 3-20. In actual applications, if the number of transmission line sub-sections is too small, the impedance variation trend of the transmission line sub-sections will not be effective. If the number of transmission line sub-sections is too large, the size will be too large, the loss will increase, and the design and processing difficulty will increase, resulting in an increase in cost. Therefore, considering the influence of cost and performance, in some embodiments, 5≤N≤10 is set to balance the influence of cost and performance. For example, N can be 5, 6, 8, 9, 10, etc., which is not limited herein.

[0142] In some embodiments, the second step-transformed planar transmission line 512 can be formed using a step-transformed microstrip line or a step-transformed stripline. For example, when the second step-transformed planar transmission line 512 is configured as a step-transformed microstrip line, the step-transformed microstrip line is divided into a first transmission line segment to an Nth transmission line segment. When the second step-transformed planar transmission line 512 is configured as a step-transformed stripline, the step-transformed stripline is divided into a first transmission line segment to an Nth transmission line segment.

[0143] The following example illustrates the structure of the second step-transformed plane transmission line 512 provided in this application embodiment, using a step-transformed microstrip line to form the second step-transformed plane transmission line 512.

[0144] Figure 9 A schematic diagram of the second-step transformation planar transmission line 512, the radio frequency transmission circuit 120, and the directly modulated laser provided in the embodiments of this application is shown below. Figure 9 The second step-conversion planar transmission line 512 may include sequentially connected first transmission line segments Ya1 to sixth transmission line segments Ya6, wherein the first transmission line segment Ya1 is used to connect to the corresponding RF transmission circuit 120, and the sixth transmission line segment Ya6 is connected to the signal input port S of the direct-modulated laser 511. LD Electrical connections can be achieved using soldering or wire bonding, with the first transmission line segment Ya1 to the sixth transmission line segment Ya6 connected in series. Furthermore, the impedances of the first transmission line segment Ya1 to the sixth transmission line segment Ya6 can satisfy the following relationship: R Ya2 >R Ya1 R Ya3 >R Ya2 R Ya4 <R Ya3 R Ya5 >R Ya4 R Ya6 <R Ya5 Furthermore, R Ya4 <R Ya6 Among them, R Ya1 R represents the impedance of the first transmission line segment Ya1. Ya2 R represents the impedance of the second transmission line segment Ya2. Ya3 R represents the impedance of the third transmission line segment Ya3. Ya4 R represents the impedance of the fourth transmission line segment Ya4. Ya5 R represents the impedance of the 5th transmission line segment Ya5. Ya6 This represents the impedance of the 6th transmission line segment Ya6.

[0145] It can be understood that the above embodiments are only examples of the specific structure of the second stepped transformation planar transmission line 512, and in actual implementation, the specific structure of the second stepped transformation planar transmission line 512 is not limited to the above structure provided by the embodiments of the present application, but can also be other structures known by those skilled in the art based on the same concept, which is not limited here.

[0146] In some embodiments of the present application, the second stepped transformation planar transmission line 512 and the direct modulation laser 511 can be integrated together as independent devices to form a transmitting optical module 500, and then the transmitting optical module 500 is mounted or arranged on a circuit board (such as a printed circuit board (PCB)) provided with a corresponding radio frequency transmission circuit to electrically connect the transmitting optical module 500 with the corresponding radio frequency transmission circuit. Exemplarily, Figure 10a A structure diagram of a transmitting optical module provided by an embodiment of the present application is shown in FIG. 5, Figure 10b A structure diagram of a transmitting PCB provided by an embodiment of the present application is shown in FIG. 6, which is described with reference to Figure 10a With Figure 10b The transmitting optical module 500 can include a direct modulation laser 511 and a transmitting PCB, and the second stepped transformation planar transmission line 512 is arranged on the transmitting PCB. One end of the transmitting PCB is welded on the direct modulation laser 511, and the one end of the transmitting PCB has a port assembly connected with the signal input port, the ground port, the detection port and the power supply input port of the direct modulation laser 511, respectively. The other end of the transmitting PCB is provided with a plurality of plug-in assemblies arranged at intervals to be mounted on a circuit board provided with a corresponding radio frequency transmission circuit. The Nth transmission line sub-section of the second stepped transformation planar transmission line 512 is connected with the port assembly on the transmitting PCB connected with the signal input port of the direct modulation laser 511 to realize the electrical connection between the Nth transmission line sub-section and the signal input port of the direct modulation laser 511, and the electrical connection between the detection port and other detection circuits. The first transmission line sub-section of the second stepped transformation planar transmission line 512 is connected with the plug-in assembly (as a radio frequency input port), so that after the transmitting optical module 500 is mounted on the circuit board provided with the corresponding radio frequency transmission circuit, the electrical connection between the first transmission line sub-section and the corresponding radio frequency transmission circuit can be realized. In some embodiments, the port assembly connected with the signal input port, the ground port, the detection port and the power supply input port can be inserted into the circuit board to realize the conduction of direct current voltage and ground voltage and the transmission of radio frequency signals. It can be understood that the second stepped transformation planar transmission line 512 can also be integrated in the direct modulation laser 511 to improve the integration and further realize miniaturization.

[0147] In some examples, the direct modulation laser 511 can include a direct modulation semiconductor laser (LD). Illustratively, the direct modulation LD can include a transmitter optical subassembly (TOSA). In practical applications, the connection mode between the direct modulation laser 511 and the second ladder conversion planar transmission line 512 can be designed according to the specific form of the direct modulation laser 511. Illustratively, the connection mode includes but is not limited to welding, wire bonding (such as gold wire bonding), etc.

[0148] In addition, since the direct modulation laser 511 not only has a signal input port, but also has a ground port, other components need to be provided in the transmitting optical module 500 to realize the overall function of the direct modulation laser 511. Figure 11 An equivalent circuit structure schematic diagram of a receiving optical module provided by an embodiment of the present application, the transmitting optical module 500 can include: a direct modulation laser 511 and a second ladder conversion planar transmission line 512 provided on a transmitting PCB, a first transmitting component 610, a first transmitting ground capacitor CY1, and a second transmitting ground capacitor CY2, wherein a first end of the first transmitting component 610 is connected with one of the first transmission line subsegment to the Nth transmission line subsegment, and a second end of the first transmitting component 610 is used to connect a power supply input port. A first electrode of the first transmitting ground capacitor CY1 is connected with a ground port G LD of the direct modulation laser 511 (for example, a ground input port component on the transmitting PCB), and a second end of the first transmitting ground capacitor CY1 is used to connect a ground input port (for example, a plug-in component on the transmitting PCB connected with the ground input port component), so that the ground port of the direct modulation laser 511 is grounded through the first transmitting ground capacitor CY1. A first electrode of the second transmitting ground capacitor CY2 is connected with a signal input port S LD of the direct modulation laser 511 (for example, a signal input port component on the transmitting PCB), and a second end of the second transmitting ground capacitor CY2 is used to connect a ground input port (for example, a plug-in component on the transmitting PCB connected with the ground input port component).

[0149] The first transmitting component 610 is used to couple the signal of the power supply input port to the transmission line sub-section connected thereto, so that the direct current voltage input by the power supply input port can be input to the signal input port of the direct modulation laser 511. Since the signal input port of the direct modulation laser 511 is used to input the radio frequency signal, in order to avoid the radio frequency signal leakage, the first transmitting component 610 can also be used to block or reduce the radio frequency signal transmission, so that the radio frequency signal can be transmitted into the signal input port of the direct modulation laser 511 through the second stepped transformation planar transmission line 512 as much as possible. Further, in order to reduce the influence of the first transmitting component 610 on the impedance and radio frequency signal leakage of each transmission line sub-section in the second stepped transformation planar transmission line 512, the first end of the first transmitting component 610 can be connected to the connection between the first transmission line sub-section and the second transmission line sub-section.

[0150] For example, referring to Figure 11 , the first transmitting component 610 can include a first transmitting inductor LY1, so as to transmit the direct current voltage and block the radio frequency signal transmission. Alternatively, the first receiving component 310 can also include a third quarter wavelength transmission line. Of course, in actual application, the first transmitting component 610 can also be other devices that can realize the above functions, which are not limited herein. In addition, the purpose of setting the first transmitting component 610 is to transmit the direct current voltage and block the radio frequency signal transmission. However, in actual application, a small amount of radio frequency signal can leak through the first transmitting component 610, but the leakage part is usually not too much, and the influence on the transmission coefficient and noise is small, which can be ignored.

[0151] It can be understood that Figure 10b only the second stepped transformation planar transmission line 512 is shown in the figure, and the first transmitting component 610, the first transmitting ground capacitor CY1 and the second transmitting ground capacitor CY2 are not shown. The implementation of the first transmitting component 610, the first transmitting ground capacitor CY1 and the second transmitting ground capacitor CY2 can be determined according to the requirements of actual application scenarios, which are not limited herein.

[0152] In some embodiments of the present application, in addition to using the second stepped transformation planar transmission line 512 for impedance matching, a lumped element network formed by capacitors and inductors can also be used for impedance matching. For example, Figure 12 Another equivalent circuit structure schematic diagram of the transmitting optical module provided by the embodiments of the present application is shown in the figure, referring to Figure 12 , the embodiments of the present application are aimed at Figure 11The embodiment shown is deformed, and the same parts are not repeated here. The difference is that the emission light module 500 includes a direct modulation laser 511 and a second lumped element network 513, wherein the first end of the second lumped element network 513 is connected to the RF output end of the corresponding RF transmission circuit 120, and the second end of the second lumped element network 513 is connected to the signal input port S LD The second end of the second lumped element network 513 is connected to the signal input port S

[0153] In some embodiments of the present application, the direct current (I)-voltage (V) data, scatter (S) parameter data and output different optical powers under different bias voltages and different frequencies can be measured to establish a circuit model of the direct modulation laser 511 related to the bias voltage, frequency and output optical power, so as to accurately characterize the electro-optical conversion process of the direct modulation laser 511. The circuit model of the direct modulation laser can include three regions: a direct current parameter region, a chip intrinsic region and a parasitic parameter region. The direct current parameter region includes a current source to represent the direct current parameter characteristics of the direct modulation laser. The chip intrinsic region includes a seventh capacitor and a seventh resistor to represent the junction capacitance of the direct modulation laser with the seventh capacitor (the junction capacitance is a variable capacitor, and the junction capacitance is related to the bias voltage) and the drift resistance of the direct modulation laser with the seventh resistor (the drift resistance is a variable resistor, and the drift resistance is related to the bias voltage). The parasitic parameter region includes an eighth capacitor, an eighth resistor and a fourth inductor to represent the parasitic resistance of the direct modulation laser with the eighth resistor, the parasitic inductance of the direct modulation laser with the fourth inductor, and the parasitic capacitance of the direct modulation laser with the eighth capacitor.

[0154] The established laser circuit model is simulated based on the requirements of matching a large bandwidth (e.g., 2 GHz-6 GHz) and a transmission coefficient greater than or equal to 0.9 to obtain the number of capacitors and inductors that meet the above requirements, and the variation law of the capacitance value of the capacitor and the inductance value of the inductor. Among them, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance values of the plurality of transmitting matching inductors increase, and the capacitance values of the plurality of transmitting matching capacitors increase. Based on this, the capacitance and inductance in the second lumped element network 513 are designed to achieve impedance matching, which can minimize the loss of the radio frequency signal during output, effectively reduce the loss of the radio frequency signal during output compared to using resistance for impedance matching, thereby improving the gain of the entire RoF network system, reducing the noise coefficient, and thus obtaining a high-performance RoF transmission link.

[0155] In some embodiments of the present application, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the difference between the inductance values of each adjacent transmitting matching inductor in the series connection can be the same. For example, taking four transmitting matching inductors in series connection as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmitting matching inductors are named as: first transmitting matching inductor, second transmitting matching inductor, third transmitting matching inductor, and fourth transmitting matching inductor, wherein the inductance value of the second transmitting matching inductor is greater than that of the first transmitting matching inductor, the inductance value of the third transmitting matching inductor is greater than that of the second transmitting matching inductor, and the inductance value of the fourth transmitting matching inductor is greater than that of the third transmitting matching inductor. And the difference between the inductance values of the first transmitting matching inductor and the second transmitting matching inductor is ΔL14, the difference between the inductance values of the second transmitting matching inductor and the third transmitting matching inductor is ΔL24, the difference between the inductance values of the third transmitting matching inductor and the fourth transmitting matching inductor is ΔL34, and ΔL14=ΔL24=ΔL34. Thus, the inductance values of the transmitting matching inductors can be increased in equal difference in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser. In addition, the present application does not limit the specific values of ΔL14, ΔL24, and ΔL34, which can be determined according to the requirements of the actual application scenario.

[0156] In some embodiments of the present application, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance values of the sequentially connected partial or all transmitting matching inductors decrease in turn. For example, taking four sequentially connected transmitting matching inductors as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmitting matching inductors are named as a first transmitting matching inductor, a second transmitting matching inductor, a third transmitting matching inductor and a fourth transmitting matching inductor, wherein the inductance value of the second transmitting matching inductor is greater than the inductance value of the first transmitting matching inductor, the inductance value of the third transmitting matching inductor is greater than the inductance value of the second transmitting matching inductor, and the inductance value of the fourth transmitting matching inductor is greater than the inductance value of the third transmitting matching inductor. Moreover, the inductance value difference between the first transmitting matching inductor and the second transmitting matching inductor is ΔL15, the inductance value difference between the second transmitting matching inductor and the third transmitting matching inductor is ΔL25, the inductance value difference between the third transmitting matching inductor and the fourth transmitting matching inductor is ΔL35, and ΔL15>ΔL25>ΔL35. Thus, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance value of the transmitting matching inductor increases based on the difference values decreasing in turn. Moreover, the present application does not limit the specific values of ΔL15, ΔL25 and ΔL35, which can be determined according to the requirements of the actual application scenario.

[0157] In some embodiments of the present application, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance values of the sequentially connected partial or all of the transmission matching inductors can be increased in turn. For example, taking four transmission matching inductors sequentially connected as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmission matching inductors are named as a first transmission matching inductor, a second transmission matching inductor, a third transmission matching inductor and a fourth transmission matching inductor, wherein the inductance value of the second transmission matching inductor is greater than the inductance value of the first transmission matching inductor, the inductance value of the third transmission matching inductor is greater than the inductance value of the second transmission matching inductor, and the inductance value of the fourth transmission matching inductor is greater than the inductance value of the third transmission matching inductor. In addition, the inductance value difference between the first transmission matching inductor and the second transmission matching inductor is ΔL16, the inductance value difference between the second transmission matching inductor and the third transmission matching inductor is ΔL26, and the inductance value difference between the third transmission matching inductor and the fourth transmission matching inductor is ΔL36, ΔL16<ΔL26<ΔL36. Thus, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the inductance value of the transmission matching inductor can be increased based on the increasing difference. In addition, the specific values of ΔL16, ΔL26 and ΔL36 are not limited in the present application, which can be determined according to the requirements of the actual application scene.

[0158] It can be understood that the above is only an example to illustrate some embodiments in which the inductance value of the transmission matching inductor increases in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser. In other embodiments, other rules can be used to realize the embodiment in which the inductance value of the transmission matching inductor increases, as long as the above-mentioned inductance value of the transmission matching inductor increases is met, which belongs to the protection scope of the present application, and the specific embodiments are not limited herein.

[0159] In some embodiments of the present application, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the capacitance values of each adjacent transmitting matching capacitor in the sequentially connected partial or all transmitting matching capacitors are the same. For example, taking four sequentially connected transmitting matching capacitors as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmitting matching capacitors are named as a first transmitting matching capacitor, a second transmitting matching capacitor, a third transmitting matching capacitor and a fourth transmitting matching capacitor, wherein the capacitance value of the second transmitting matching capacitor is greater than that of the first transmitting matching capacitor, the capacitance value of the third transmitting matching capacitor is greater than that of the second transmitting matching capacitor, and the capacitance value of the fourth transmitting matching capacitor is greater than that of the third transmitting matching capacitor. Moreover, the capacitance value difference between the first transmitting matching capacitor and the second transmitting matching capacitor is ΔC14, the capacitance value difference between the second transmitting matching capacitor and the third transmitting matching capacitor is ΔC24, and the capacitance value difference between the third transmitting matching capacitor and the fourth transmitting matching capacitor is ΔC34, ΔC14=ΔC24=ΔC34. Thus, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the capacitance values of the transmitting matching capacitors can be increased in equal difference. Moreover, the present application does not limit the specific values of ΔC14, ΔC24 and ΔC34, which can be determined according to the requirements of the actual application scenario.

[0160] In some other embodiments of the present application, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the sequentially connected part or all of the transmitting matching capacitors can also be arranged in such a way that the difference between the capacitance values of each adjacent transmitting matching capacitor decreases in turn. For example, taking four sequentially connected transmitting matching capacitors as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmitting matching capacitors are named as: the first transmitting matching capacitor, the second transmitting matching capacitor, the third transmitting matching capacitor and the fourth transmitting matching capacitor, wherein the capacitance value of the second transmitting matching capacitor is greater than that of the first transmitting matching capacitor, the capacitance value of the third transmitting matching capacitor is greater than that of the second transmitting matching capacitor, and the capacitance value of the fourth transmitting matching capacitor is greater than that of the third transmitting matching capacitor. Moreover, the difference between the capacitance values of the first transmitting matching capacitor and the second transmitting matching capacitor is ΔC15, the difference between the capacitance values of the second transmitting matching capacitor and the third transmitting matching capacitor is ΔC25, and the difference between the capacitance values of the third transmitting matching capacitor and the fourth transmitting matching capacitor is ΔC35, ΔC15>ΔC25>ΔC35. In this way, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the capacitance value of the transmitting matching capacitor can be increased based on the difference that decreases in turn. Moreover, the present application does not limit the specific values of ΔC15, ΔC25 and ΔC35, which can be determined according to the requirements of the actual application scenario.

[0161] In some embodiments of the present application, the capacitance values of the sequentially connected partial or all of the transmitting matching capacitors can be increased in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser. For example, taking four sequentially connected transmitting matching capacitors as an example, in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser, the four transmitting matching capacitors are named as a first transmitting matching capacitor, a second transmitting matching capacitor, a third transmitting matching capacitor and a fourth transmitting matching capacitor, wherein the capacitance value of the second transmitting matching capacitor is greater than the capacitance value of the first transmitting matching capacitor, the capacitance value of the third transmitting matching capacitor is greater than the capacitance value of the second transmitting matching capacitor, and the capacitance value of the fourth transmitting matching capacitor is greater than the capacitance value of the third transmitting matching capacitor. In addition, the capacitance value difference between the first transmitting matching capacitor and the second transmitting matching capacitor is ΔC16, the capacitance value difference between the second transmitting matching capacitor and the third transmitting matching capacitor is ΔC26, and the capacitance value difference between the third transmitting matching capacitor and the fourth transmitting matching capacitor is ΔC36, ΔC16<ΔC26<ΔC36. Thus, the capacitance values of the transmitting matching capacitors can be increased in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser based on the increasing difference. In addition, the specific values of ΔC16, ΔC26 and ΔC36 are not limited in the present application, which can be determined according to the requirements of the actual application scene.

[0162] It can be understood that the above is only an example to illustrate some embodiments in which the capacitance values of the transmitting matching capacitors increase in the direction from the radio frequency output end of the radio frequency transmission circuit to the signal input port of the direct modulation laser. In other embodiments, other rules can be used to realize the embodiments in which the capacitance values of the transmitting matching capacitors increase, as long as the above-mentioned trend of increasing capacitance values of the transmitting matching capacitors is met, which belongs to the protection scope of the present application, and the specific embodiments are not limited herein.

[0163] As an example, refer to Figure 12, the plurality of transmission matching inductors comprises a first transmission matching inductor Ln1, a second transmission matching inductor Ln2 and a third transmission matching inductor Ln3, and the plurality of transmission matching capacitors comprises a first transmission matching capacitor Cn1, a second transmission matching capacitor Cn2 and a third transmission matching capacitor Cn3, wherein a first end of the first transmission matching inductor Ln1 is connected with a first end of the first transmission matching capacitor Cn1 and the radio frequency input port respectively, a second end of the first transmission matching inductor Ln1 is connected with a first end of the second transmission matching inductor Ln2 and a first end of the second transmission matching capacitor Cn2 respectively, a second end of the second transmission matching inductor Ln2 and a first end of the third transmission matching inductor Ln3 are connected with each other, and a second end of the third transmission matching inductor Ln3 is connected with the signal input port S of the direct modulation laser 511 LD , a second end of the first transmission matching capacitor Cn1, a second end of the second transmission matching capacitor Cn2 and a second end of the third transmission matching capacitor Cn3 are all connected to the ground input port. In this way, the second lumped element network can be implemented by using a simple structure to achieve impedance matching. In addition, the radio frequency input port is used to be connected to a radio frequency output of a radio frequency transmission circuit.

[0164] The inductance value of the first transmission matching inductor Ln1 is smaller than the inductance value of the second transmission matching inductor Ln2, and the inductance value of the second transmission matching inductor Ln2 is smaller than the inductance value of the third transmission matching inductor Ln3. Exemplarily, the difference between the inductance value of the first transmission matching inductor Ln1 and the inductance value of the second transmission matching inductor Ln2 is Δ3, and the difference between the inductance value of the second transmission matching inductor Ln2 and the inductance value of the third transmission matching inductor Ln3 is Δ4, Δ3 can be equal to Δ4, or Δ3 can be greater than Δ4, or Δ3 can be smaller than Δ4, which is not limited herein.

[0165] The capacitance value of the first transmission matching capacitor Cn1 is smaller than the capacitance value of the second transmission matching capacitor Cn2, and the capacitance value of the second transmission matching capacitor Cn2 is smaller than the capacitance value of the third transmission matching capacitor Cn3. Exemplarily, the difference between the capacitance value of the first transmission matching capacitor Cn1 and the capacitance value of the second transmission matching capacitor Cn2 is Δ5, and the difference between the capacitance value of the second transmission matching capacitor Cn2 and the capacitance value of the third transmission matching capacitor Cn3 is Δ6, Δ5 can be equal to Δ6, or Δ5 can be greater than Δ6, or Δ5 can be smaller than Δ6, which is not limited herein.

[0166] It can be understood that the example is only used to illustrate the specific structure of the second lumped element network 513, and the specific structure of the second lumped element network 513 is not limited to the above structure provided by the embodiments of the present application in the specific implementation, but can also be other structures known by those skilled in the art based on the same concept, which is not limited herein.

[0167] In some embodiments, Figure 12 The transmitting optical module 500 can further include a second transmitting inductor LY2, a first end of the second transmitting inductor LY2 being connected with the signal input port S LD of the direct modulation laser 511, and a second end of the second transmitting inductor LY2 being used for connecting the power input port. In this way, the direct current voltage of the power input port can be coupled to the signal input port S LD of the direct modulation laser 511 through the second transmitting inductor LY2. In some embodiments, the second transmitting inductor LY2 can also block or reduce the amount of the radio frequency signal passing through. In actual applications, a small amount of the radio frequency signal can leak through the second transmitting inductor LY2, but the amount of the leaked radio frequency signal is weak, and the weak leaked radio frequency signal has little effect on the transmission coefficient and noise, which can be ignored.

[0168] In some embodiments, Figure 12 The transmitting optical module 500 can further include a third transmitting ground capacitor CY3, a first electrode of the third transmitting ground capacitor CY3 being connected with the ground port G LD of the direct modulation laser 511, and a second end of the third transmitting ground capacitor CY3 being used for connecting the ground input port. In this way, the ground port G LD of the direct modulation laser 511 can be grounded through the third transmitting ground capacitor CY3. In some embodiments, the third transmitting ground capacitor CY3 can also block or reduce the amount of the radio frequency signal passing through. In actual applications, a small amount of the radio frequency signal can leak through the third transmitting ground capacitor CY3, but the amount of the leaked radio frequency signal is usually small, and the weak leaked radio frequency signal has little effect on the transmission coefficient and noise, which can be ignored.

[0169] In some embodiments, Figure 12 The transmitting optical module 500 can further include a fourth transmitting ground capacitor CY4, a first electrode of the fourth transmitting ground capacitor CY4 being connected with the ground port of the direct modulation laser 511, and a second end of the fourth transmitting ground capacitor CY4 being used for connecting the ground input port. In some other embodiments of the present application, the fourth transmitting ground capacitor CY4 can be removed to reduce the number of capacitor devices when the performance of the transmitting optical module 500 meets the requirements.

[0170] The present application also takes the input impedance of the direct modulation laser 511 as 9.492-j14.9 ohms, and the output impedance of the connected radio frequency transmission circuit as 50 ohms as an example, and combines Figure 12The structure shown is simulated, and the impedance matching requirement of 2.7 GHz frequency point is met by setting the inductance value of the first transmission matching inductor Ln1 to 1.12 nH, the inductance value of the second transmission matching inductor Ln2 to 1.14 nH, the inductance value of the third transmission matching inductor Ln3 to 1.66 nH, the capacitance value of the first transmission matching capacitor Cn1 to 0.56 pF, the capacitance value of the second transmission matching capacitor Cn2 to 0.97 pF, and the capacitance value of the third transmission matching capacitor Cn3 to 2.97 pF, so that the transmission coefficient of the radio frequency signal in the transmission process is greater than 0.95, thereby minimizing the loss of the radio frequency signal in the transmission process.

[0171] In some embodiments, Figure 12 The corresponding specific structural diagram can be referred to Figure 10a to Figure 11 The structure shown is designed, and details are not described here.

[0172] The above optical module of the embodiments of the present application can be used in various devices, such as servers, routing devices, switching devices or other communication devices.

[0173] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A receiving optical module, characterized in that, The application relates to a receiving optical module. The receiving optical module comprises a photoelectric detector and a first stepped transformation planar transmission line, the first stepped transformation planar transmission line comprises sequentially connected first transmission line subsegments to Mth transmission line subsegments, the first transmission line subsegment is connected with a signal output port of the photoelectric detector, and the Mth transmission line subsegment is used for connecting a radio frequency input end of a radio frequency transmission circuit; M is an integer and M>=3; Impedances of at least one of the second transmission line subsegment to the M-1th transmission line subsegment are less than the impedance of the first transmission line subsegment.

2. The receiving optical module according to claim 1, wherein M>=4, the impedance of each of the first transmission line subsegment to the Mth transmission line subsegment is sequentially reduced, increased and then reduced again.

3. The receiving optical module according to claim 2, wherein The impedance of each of the first transmission line subsegment to the Mth transmission line subsegment is sequentially reduced, then sequentially increased to be greater than the impedance of the Mth transmission line subsegment, and finally sequentially reduced to the impedance of the Mth transmission line subsegment.

4. The receiving optical module according to claim 2 or 3, wherein The impedance of the second transmission line subsegment is less than the impedance of the first transmission line subsegment and the impedance of the third transmission line subsegment; Or, the impedance of the third transmission line subsegment is less than the impedance of the second transmission line subsegment and the impedance of the fourth transmission line subsegment, and the impedance of the second transmission line subsegment is less than the impedance of the first transmission line subsegment; Or, the impedance of the M-1th transmission line subsegment is greater than the impedance of the Mth transmission line subsegment and the impedance of the M-2th transmission line subsegment; Or, the impedance of the M-2th transmission line subsegment is greater than the impedance of the M-1th transmission line subsegment and the impedance of the M-3th transmission line subsegment, and the impedance of the M-1th transmission line subsegment is greater than the impedance of the Mth transmission line subsegment.

5. The receiving optical module according to any one of claims 2 to 4, wherein 4≤M≤10； Or, the difference between the impedance of the first transmission line subsegment and the output impedance of the signal output port of the photoelectric detector is close to zero or equal to zero, and the difference between the impedance of the Mth transmission line subsegment and the input impedance of the radio frequency input end of the radio frequency transmission circuit is close to zero or equal to zero; Or, the first stepped transformation planar transmission line comprises a stepped transformation microstrip line or a stepped transformation strip line.

6. The receiving optical module according to any one of claims 1 to 5, wherein The receiving optical module further comprises a first receiving component, a first end of the first receiving component is connected with one of the first transmission line subsegment to the Mth transmission line subsegment, and a second end of the first receiving component is used for connecting a power supply input port or a grounding input port; The first receiving component is used for coupling a signal of the power supply input port or the grounding input port to the transmission line subsegment connected with the first receiving component and blocking a radio frequency signal.

7. The receiving optical module according to claim 6, wherein The first end of the first receiving component is connected to a connection between the first transmission line subsegment and the second transmission line subsegment; or The first receiving component comprises a first quarter wavelength transmission line or a first receiving inductance.

8. The receiving optical module according to claim 6 or 7, wherein When the second end of the first receiving component is used for connecting the grounding input port, the receiving optical module further comprises a first receiving grounding capacitor and a second receiving component. The first electrode of the first receiving ground capacitor is connected to the first ground port of the photodetector, and the second electrode of the first receiving ground capacitor is used to connect the ground input port. The first receiving ground capacitor and the second receiving component are used to couple signals of the power supply input port to the first ground port of the photodetector, and the second receiving component is also used to block radio frequency signals.

9. The receiving optical module according to claim 8, wherein The second receiving component includes a second quarter-wavelength transmission line or a second receiving inductor.

10. The receiving optical module according to claim 6 or 7, wherein The second end of the first receiving component is used to connect the power supply input port, and the receiving optical module further includes a second receiving ground capacitor. The first electrode of the second receiving ground capacitor is connected to the first ground port of the photodetector, and the second electrode of the second receiving ground capacitor is used to connect the ground input port.

11. The receiving optical module according to any one of claims 1 to 10, wherein The receiving optical module further includes a third receiving ground capacitor, the first electrode of the third receiving ground capacitor is connected to the second ground port of the photodetector, and the second electrode of the third receiving ground capacitor is used to connect the ground input port.

12. A receiving optical module characterized by comprising: It includes: a photodetector and a first network of lumped elements; The first end of the first network of lumped elements is connected to the signal output port of the photodetector, and the second end of the first network of lumped elements is used to connect the radio frequency input end of the radio frequency transmission circuit; The first network of lumped elements includes a plurality of receiving matching capacitors and a plurality of receiving matching inductors, the plurality of receiving matching inductors are connected in series between the signal output port of the photodetector and the radio frequency input end of the radio frequency transmission circuit, and the two ends of at least part of the receiving matching inductors are connected to the first end of one of the receiving matching capacitors, and the second end of the plurality of receiving matching capacitors is used to connect the ground input port. In the direction from the signal output port of the photodetector to the radio frequency input end of the radio frequency transmission circuit, the inductance values of the plurality of receiving matching inductors show a decreasing trend, and the capacitance values of the plurality of receiving matching capacitors show a decreasing trend.

13. The receiving optical module of claim 12, wherein, The plurality of receiving matching inductors includes a first receiving matching inductor and a second receiving matching inductor, and the plurality of receiving matching capacitors includes a first receiving matching capacitor, a second receiving matching capacitor, and a third receiving matching capacitor. The first end of the first receiving matching inductor is connected to the first end of the first receiving matching capacitor and the signal output port of the photodetector, respectively, the second end of the first receiving matching inductor is connected to the first end of the second receiving matching inductor and the first end of the second receiving matching capacitor, respectively, the second end of the second receiving matching inductor is connected to the first end of the third receiving matching capacitor and the radio frequency input end of the radio frequency transmission circuit, respectively, and the second end of the first receiving matching capacitor, the second end of the second receiving matching capacitor, and the second end of the third receiving matching capacitor are all connected to the ground input port.

14. The receiving optical module according to claim 12 or 13, wherein The receiving optical module further comprises a third receiving inductor, a first end of the third receiving inductor is connected with a signal output port of the photodetector, and a second end of the third receiving inductor is used for connecting a power supply input port.

15. The receiving optical module according to any one of claims 13 to 14, wherein The receiving optical module further comprises a fourth receiving ground capacitor, a first electrode of the fourth receiving ground capacitor is connected with a first ground port of the photodetector, and a second electrode of the fourth receiving ground capacitor is used for connecting a ground input port; or, The receiving optical module further comprises a fifth receiving ground capacitor, a first electrode of the fifth receiving ground capacitor is connected with a second ground port of the photodetector, and a second electrode of the fifth receiving ground capacitor is used for connecting a ground input port.

16. An optical transmitting module, comprising: Comprise: A direct modulation laser and a second step transformation planar transmission line, the second step transformation planar transmission line comprises sequentially connected first to Nth transmission line subsegments, the first transmission line subsegment is used for connecting a radio frequency output end of a radio frequency transmission circuit, and the Nth transmission line subsegment is connected with a signal input port of the direct modulation laser; N is an integer and N≥3; Impedances of at least one of the second to N-1th transmission line subsegments are less than an impedance of the Nth transmission line subsegment.

17. The light emitting module of claim 16, wherein, N≥5, the impedance of each of the first to Nth transmission line subsegments is sequentially increased, decreased, increased again, and decreased again.

18. The light emitting module of claim 17, wherein, The impedance of each of the first to Nth transmission line subsegments is sequentially increased and then sequentially decreased to be less than the impedance of the Nth transmission line subsegment, then sequentially increased to be greater than the impedance of the Nth transmission line subsegment, and finally sequentially decreased to the impedance of the Nth transmission line subsegment.

19. The light emitting module of claim 17 or 18, wherein, The impedance of the second transmission line subsegment is greater than the impedance of the first transmission line subsegment and the impedance of the third transmission line subsegment; Or, the impedance of the third transmission line subsegment is greater than the impedance of the second transmission line subsegment and the impedance of the fourth transmission line subsegment, and the impedance of the second transmission line subsegment is greater than the impedance of the first transmission line subsegment; Or, the impedance of the N-1th transmission line subsegment is greater than the impedance of the Nth transmission line subsegment and the impedance of the N-2th transmission line subsegment, and the impedance of the N-2th transmission line subsegment is less than the impedance of the Nth transmission line subsegment and the impedance of the N-3th transmission line subsegment; Or, the impedance of the N-2th transmission line subsegment is greater than the impedance of the N-1th transmission line subsegment and the impedance of the N-3th transmission line subsegment, the impedance of the N-1th transmission line subsegment is greater than the impedance of the Nth transmission line subsegment, and the impedance of the N-3th transmission line subsegment is less than the impedance of the Nth transmission line subsegment and the impedance of the N-4th transmission line subsegment.

20. The light emitting module of any of claims 16-19, wherein, 5≤N≤10； Or, a difference between the impedance of the first transmission line subsegment and an output impedance of the radio frequency output end of the radio frequency transmission circuit is close to zero or equal to zero, and a difference between the impedance of the Nth transmission line subsegment and an input impedance of the signal input port of the direct modulation laser is close to zero or equal to zero; Or, the second step transformation planar transmission line comprises a step transformation microstrip line or a step transformation stripline.

21. The light emitting module of any of claims 16-20, wherein, The transmitting optical module further comprises a first transmitting component, a first end of the first transmitting component is connected with one of the first transmission line sub-section and the Nth transmission line sub-section, and a second end of the first transmitting component is used for connecting a power supply input port; The second receiving component is used for coupling a signal of the power supply input port to the transmission line sub-section connected therewith and blocking a radio frequency signal from passing through.

22. The light emitting module of claim 21, wherein, The first end of the first transmitting component is connected to a connection between the first transmission line sub-section and the second transmission line sub-section; or, The first transmitting component comprises a third quarter wavelength transmission line or a first transmitting inductance.

23. The light emitting module of any of claims 16-22, wherein, The transmitting optical module further comprises a first transmitting ground capacitor, a first electrode of the first transmitting ground capacitor is connected with a ground port of the direct modulation laser, and a second end of the first transmitting ground capacitor is used for connecting a ground input port; Alternatively, the transmitting optical module further comprises a second transmitting ground capacitor, a first electrode of the second transmitting ground capacitor is connected with a signal input port of the direct modulation laser, and a second end of the second transmitting ground capacitor is used for connecting a ground input port.

24. An optical transmitting module, comprising: Comprise: a direct modulation laser and a second lumped element network, a first end of the second lumped element network is used for connecting a radio frequency output of a radio frequency transmission circuit, and a second end of the second lumped element network is connected with a signal input port of the direct modulation laser; The second lumped element network comprises a plurality of transmitting matching capacitors and a plurality of transmitting matching inductances, the plurality of transmitting matching inductances are connected in series between the radio frequency output of the radio frequency transmission circuit and the signal input port of the direct modulation laser in sequence, two ends of at least part of the transmitting matching inductances are connected with a first end of one of the transmitting matching capacitors in one-to-one correspondence, and second ends of the plurality of transmitting matching capacitors are used for connecting a ground input port; In a direction from the radio frequency output of the radio frequency transmission circuit to the signal input port of the direct modulation laser, inductance values of the plurality of transmitting matching inductances show an increasing trend, and capacitance values of the plurality of transmitting matching capacitors show an increasing trend.

25. The light emitting module of claim 24, wherein, The plurality of transmitting matching inductances comprise a first transmitting matching inductance, a second transmitting matching inductance and a third transmitting matching inductance, and the plurality of transmitting matching capacitors comprise a first transmitting matching capacitor, a second transmitting matching capacitor and a third transmitting matching capacitor; A first end of the first transmitting matching inductance is connected with a first end of the first transmitting matching capacitor and the radio frequency output of the radio frequency transmission circuit respectively, a second end of the first transmitting matching inductance is connected with a first end of the second transmitting matching inductance and a first end of the second transmitting matching capacitor respectively, a second end of the second transmitting matching inductance and a first end of the third transmitting matching inductance are connected with each other, a second end of the third transmitting matching inductance is connected with the signal input port of the direct modulation laser, and second ends of the first transmitting matching capacitor, the second transmitting matching capacitor and the third transmitting matching capacitor are used for connecting the ground input port.

26. The light emitting module of claim 24 or 25, wherein, The transmitting optical module further comprises a second transmitting inductor, a first end of the second transmitting inductor is connected with the signal input port of the direct modulation laser, and a second end of the second transmitting inductor is used for connecting the power input port; Alternatively, the transmitting optical module further comprises a third transmitting ground capacitor, a first electrode of the third transmitting ground capacitor is connected with the ground port of the direct modulation laser, and a second end of the third transmitting ground capacitor is used for connecting the ground input port; Alternatively, the transmitting optical module further comprises a fourth transmitting ground capacitor, a first electrode of the fourth transmitting ground capacitor is connected with the ground port of the direct modulation laser, and a second end of the fourth transmitting ground capacitor is used for connecting the ground input port.

27. A transceiver optical module characterized by comprising: Comprise: one or more receiving optical modules according to any one of claims 1-15, and one or more transmitting optical modules according to any one of claims 16-26.

28. An electronic device, comprising: Comprise: a receiving optical module according to any one of claims 1-15, or a transmitting optical module according to any one of claims 16-26, or a transceiving optical module according to claim 27.

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