A photoelectric hybrid frequency mixing device, a coherent ranging system and a method thereof

Abstract

The present invention discloses an optoelectronic hybrid frequency mixing device, a coherent ranging system and a method thereof. The device comprises: a phase modulation unit and a 2×2 power beam splitter. The phase modulation unit modulates a first optical signal to obtain a first modulated optical signal; the 2×2 power beam splitter mixes a second optical signal and a first modulated optical signal. When the level is low, two ports respectively output a third optical signal and a fifth optical signal. When the level is high, two ports respectively output a fourth optical signal and a sixth optical signal. In the third optical signal and the fourth optical signal, the phase difference between the two signal components contained in each optical signal is 90 degrees. In the fifth optical signal and the sixth optical signal, the phase difference between the two signal components contained in each optical signal is 90 degrees. By implementing the present invention, a phase modulation unit is introduced to modulate the optical signal, and a 2×2 power beam splitter is subsequently used to realize the mixing function of the existing 2×4 multimode interference coupler, thereby simplifying the mixer structure.

Description

Technical Field

[0001] The present invention relates to the technical field of coherent detection, and in particular to a photoelectric hybrid frequency mixing device, a coherent ranging system and a method thereof. Background Art

[0002] In recent years, with the promotion of unmanned driving technology, laser ranging systems have played an irreplaceable and important role. Compared with direct detection systems, coherent detection systems have better performance in detection capability, conversion gain, signal-to-noise ratio and stability, so they are increasingly widely used in laser detection devices.

[0003] The mixer, especially the 90° mixer, is a key component in the coherent detection system. Its performance and size have a significant impact on the performance of the coherent detection system.

[0004] The existing 90° mixer implementation solutions mainly include bulk optical solutions and integrated chip solutions. Among them, the integrated optical solutions are mostly based on 2×4 multimode interference coupler (MMI) design, which leads to complex structure and large area of ​​single detection unit and complex signal analysis method, which is not conducive to the application and integrated development of mixers in coherent systems. Summary of the invention

[0005] In view of this, the embodiments of the present invention provide an optoelectronic hybrid frequency mixing device, a coherent ranging system and a method thereof to solve the technical problem of the complex structure of the existing mixer design scheme.

[0006] According to a first aspect of an embodiment of the present invention, an optoelectronic hybrid mixing device includes: a phase modulation unit and a 2×2 power splitter, wherein the phase modulation unit is used to receive a first optical signal, and obtain a first modulated optical signal after periodically phase modulating the first optical signal; the 2×2 power splitter is used to receive a second optical signal and the first modulated optical signal, and mix the second optical signal and the first modulated optical signal, during a low level duration, the first port of the 2×2 power splitter outputs a third optical signal, and the second port of the 2×2 power splitter outputs a fifth optical signal, during a high level duration, the first port of the 2×2 power splitter outputs a fourth optical signal, and the second port of the 2×2 power splitter outputs a sixth optical signal, wherein the third optical signal, the fourth optical signal, the fifth optical signal, and the sixth optical signal all include the first modulated optical signal and the second optical signal after mixing, and in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees.

[0007] Optionally, the optoelectronic hybrid mixing device also includes: a first detection unit and a second detection unit, the first detection unit is used to receive the third optical signal and the fourth optical signal, and convert the third optical signal and the fourth optical signal into a third electrical signal and a fourth electrical signal, respectively; the second detection unit is used to receive the fifth optical signal and the sixth optical signal, and convert the fifth optical signal and the sixth optical signal into a fifth electrical signal and a sixth electrical signal, respectively.

[0008] Optionally, the phases of the third optical signal and the fourth optical signal are respectively -90° and 180°, and the phases of the fifth optical signal and the sixth optical signal are respectively 90° and 0°.

[0009] Optionally, the 2×2 power beam splitter includes any one of a 2×2 multimode interference coupler, a 2×2 directional coupler, a ring cavity coupler, a star coupler, a Fresnel lens array based on a slab waveguide, a super lens array based on a slab waveguide, and a semi-transparent and semi-reflective mirror.

[0010] Optionally, the modulation mechanism of the phase modulation unit includes: any one of: photoelectric effect, elastic-optic effect, magneto-optic effect, and phase change effect.

[0011] Optionally, the optoelectronic hybrid mixer further includes: an attenuation unit, which is used to attenuate the optical signal output by the 2×2 power splitter so that the powers of the attenuated third optical signal and the fifth optical signal are equal, and the powers of the fourth optical signal and the sixth optical signal are equal.

[0012] A second aspect of an embodiment of the present invention provides a coherent ranging system, comprising: a signal generating module, a data processing module, and the optoelectronic hybrid mixing device described in the first aspect of the embodiment of the present invention and any one of the first aspects, wherein the signal generating module is used to output a first optical signal and a first detection signal; the optoelectronic hybrid mixing device is used to receive the first optical signal and a second optical signal reflected by the first detection signal through a target to be detected, and to obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal, and a sixth electrical signal after modulating, mixing, and detecting the first optical signal and the second optical signal; and the data processing module is used to obtain the distance information of the target to be detected after processing and calculating the third electrical signal, the fourth electrical signal, the fifth electrical signal, and the sixth electrical signal.

[0013] Optionally, the signal generating module comprises: a light emitting unit, a beam splitting unit and an optical transceiver unit, wherein the light emitting unit is used to output a laser signal; the beam splitting unit is used to split the laser signal to obtain a first optical signal and a second detection signal;

[0014] The optical transceiver unit is used to collimate and transmit the first detection signal to the target to be detected, receive and output the second optical signal reflected by the target to be detected.

[0015] Optionally, the data processing module includes: a differential amplifier unit and a Fourier unit, the differential amplifier unit is used to output the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal after differential amplification; the Fourier unit is used to calculate the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal after differential amplification to obtain distance information of the target to be detected.

[0016] A third aspect of an embodiment of the present invention provides a coherent ranging method, comprising: dividing a laser signal output by a light emitting unit into a first light signal and a first detection signal, wherein the first detection signal is irradiated on a target to be detected and reflected to obtain a second light signal; after phase modulating the first light signal or the second light signal, mixing it with a light signal that has not been phase modulated to obtain a third light signal and a fifth light signal with a low level duration, and a fourth light signal and a sixth light signal with a high level duration, wherein the third light signal, the fourth light signal, the fifth light signal and the sixth light signal all contain the mixed first modulated light signal and the second light signal. signal, in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees; the third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal are converted by the first detection unit and the second detection unit respectively to obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal and a sixth electrical signal; the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal are processed and calculated to obtain the distance information of the target to be detected.

[0017] The technical solution of the present invention has the following advantages:

[0018] The optoelectronic hybrid mixing device provided in the embodiment of the present invention introduces a phase modulation unit to periodically phase modulate the optical signal, and subsequently uses a 2×2 power splitter to enable the mixing device to realize the existing 2×4 multi-mode interference coupler mixing function, thereby simplifying the mixer structure and reducing the size of the mixer.

[0019] The coherent ranging system provided by the embodiment of the present invention adopts the above-mentioned optoelectronic hybrid frequency mixing device to achieve frequency mixing, which simplifies the structure of the frequency mixer and reduces the size of the frequency mixer compared to the existing frequency mixer. In addition, the system is provided with a signal generation module and a data processing module, and the detection of the distance of the target to be detected is achieved by processing and calculating the reflected signal of the target to be detected.

[0020] The coherent ranging method provided by the embodiment of the present invention, when mixing the first optical signal and the second optical signal, firstly performs periodic phase modulation on the first optical signal or the second optical signal, and then mixes the modulated optical signal with the unmodulated optical signal, thereby reducing the volume of the mixer used. At the same time, the coherent ranging method can obtain the distance information of the target to be detected by processing and calculating the electrical signal after the detection conversion using the Fourier method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a structural block diagram of the optoelectronic hybrid frequency mixing device in an embodiment of the present invention;

[0023] Figure 2 It is a structural block diagram of an optoelectronic hybrid frequency mixing device in another embodiment of the present invention;

[0024] Figure 3 It is a structural block diagram of an optoelectronic hybrid frequency mixing device in another embodiment of the present invention;

[0025] Figure 4 is a structural block diagram of a coherent detection system in an embodiment of the present invention;

[0026] Figure 5 is a structural block diagram of a coherent detection system in another embodiment of the present invention;

[0027] Figure 6 4 is a flow chart of a coherent ranging method in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The embodiment of the present invention provides an optoelectronic hybrid frequency mixing device, such as Figure 1 As shown, the device includes: a phase modulation unit 101 and a 2×2 power beam splitter 102, the phase modulation unit 101 is used to receive a first optical signal, and obtain a first modulated optical signal after periodically phase modulating the first optical signal; the 2×2 power beam splitter is used to receive a second optical signal and a first modulated optical signal, and mix the second optical signal and the first modulated optical signal, during a low level duration, the first port of the 2×2 power beam splitter outputs a third optical signal, and the second port of the 2×2 power beam splitter outputs a fifth optical signal, during a high level duration, the first port of the 2×2 power beam splitter outputs a fourth optical signal, and the second port of the 2×2 power beam splitter outputs a sixth optical signal, the third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal all contain the first modulated optical signal and the second optical signal after mixing, in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees.

[0033] The optoelectronic hybrid mixing device provided in an embodiment of the present invention introduces a phase modulation unit 101 to perform periodic phase modulation on the optical signal, and subsequently uses a 2×2 power splitter 102 to enable the mixing device to realize the existing 2×4 multi-mode interference coupler mixing function, thereby simplifying the mixer structure and reducing the size of the mixer.

[0034] It should be noted that, for the existing 2×4 multimode interference coupler, when it is used in a coherent detection system, the four output signals of the 2×4 multimode interference coupler are differentially amplified and then orthogonally synthesized after mixing. The 2×2 power beam splitter in the optoelectronic hybrid mixer can achieve the same function as the 2×4 multimode interference coupler. Specifically, the 2×2 power beam splitter differentially amplifies the four optical signals within the high and low level durations and then performs orthogonal synthesis. Therefore, the optoelectronic hybrid mixer provided in the embodiment of the present invention simplifies the mixing structure and reduces the size of the mixer, while ensuring the consistency of the mixing function with the 2×4 multimode interference coupler in terms of mixing function.

[0035] In one embodiment, the modulation mechanism of the phase modulation unit 101 includes: any one of: photoelectric effect, elastic-optic effect, magneto-optic effect, and phase change effect. In a specific implementation, the modulation principle of the phase modulation unit 101 is explained by taking the photoelectric effect as an example. Specifically, the phase modulation unit 101 can use a phase shifter. When the mixing device is working, a voltage of a first preset value is added to the phase shifter so that the optical signal passing through the phase shifter generates a phase shift; at the same time, a voltage of a second preset value can also be added to the phase shifter so that the optical signal passing through the phase shifter does not generate a phase shift. Thus, Figure 2 As shown, when the phase shifter is used in the mixing device, the voltage of the first preset value and the voltage of the second preset value can be loaded on the phase shifter in the form of a square wave, so that the optical signal modulated by the phase shifter generates a 90° phase shift or no phase shift signal with the same period as the loaded square wave.

[0036] In one embodiment, after the first modulated optical signal and the second optical signal enter the 2×2 power beam splitter 102, the light beams are first combined and then split at the output end to obtain two optical signals. Specifically, since the first modulated optical signal is periodic, the two optical signals output by the 2×2 power beam splitter 102 are also two groups of signals arranged periodically, that is, during the low level duration, the two output ports of the 2×2 power beam splitter 102 respectively output the third optical signal and the fifth optical signal, and during the high level duration, the two output ports of the 2×2 power beam splitter 102 respectively output the fourth optical signal and the sixth optical signal, wherein the third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal all include the first modulated optical signal and the second optical signal after mixing, and in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees.

[0037] Specifically, Figure 2 As shown, the second optical signal is represented by Sig, the first optical signal is represented by Lo, and after the first modulated optical signal and the second optical signal are mixed by the 2×2 power splitter, the third optical signal and the fourth optical signal output by the first port of the 2×2 power splitter are represented by Sig*exp(i0)+Lo*exp(i90) and Sig*exp(i0)+Lo*exp(i180), respectively. In the high level duration, the first optical signal is subjected to a 90-degree phase shift by the phase modulation unit to obtain the first modulated optical signal, that is, the signal component Lo*exp(i180) contained in the fourth optical signal has a phase of 90 degrees. Therefore, the phase difference between the two signal components respectively contained in the third optical signal and the fourth optical signal, that is, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees. At the same time, since the two signal components contained in the third optical signal and the fourth optical signal themselves have a phase difference, it can be concluded that the phases of the third optical signal and the fourth optical signal are -90° and 180°, respectively.

[0038] At the same time, after the first modulated optical signal and the second optical signal are mixed by the 2×2 power beam splitter, the fifth optical signal and the sixth optical signal outputted by the second port of the 2×2 power beam splitter are respectively expressed as Sig*exp(i90)+Lo*exp(i0) and Sig*exp(i90)+Lo*exp(i90). Similarly, during the high level duration, the first optical signal is obtained by a 90-degree phase shift after the phase modulation unit, that is, the signal component Lo*exp(i180) contained in the sixth optical signal has a phase of 90 degrees. Therefore, the phase difference between the two signal components contained in the fifth optical signal and the sixth optical signal, that is, the first modulated optical signal and the second optical signal after mixing, is 90 degrees. At the same time, since the two signal components contained in the fifth optical signal and the sixth optical signal have their own phase phase, it can be concluded that the phases of the fifth optical signal and the sixth optical signal are 90° and 0°, respectively.

[0039] In one embodiment, the 2×2 power splitter 102 can select any one of a 2×2 multimode interference coupler, a 2×2 directional coupler, a ring cavity coupler, a star coupler, a Fresnel lens array based on a slab waveguide, a super lens array based on a slab waveguide, and a semi-transparent and semi-reflective mirror.

[0040] In one embodiment, in order to facilitate the analysis of the signal, Figure 3 As shown, the optoelectronic hybrid frequency mixing device also includes: a first detection unit 103 and a second detection unit 104, the first detection unit 103 is used to receive the third optical signal and the fourth optical signal, and convert the third optical signal and the fourth optical signal into a third electrical signal and a fourth electrical signal respectively; the second detection unit 104 is used to receive the fifth optical signal and the sixth optical signal, and convert the fifth optical signal and the sixth optical signal into a fifth electrical signal and a sixth electrical signal respectively. In a specific embodiment, the first detection unit 103 and the second detection unit 104 can respectively select photodetectors, such as any one of a single photon avalanche diode, an avalanche photodiode, a silicon photomultiplier tube or a PIN photodiode. In one embodiment, the maximum detectable bandwidth of the first detection unit 103 and the second detection unit 104 can be less than the signal frequency of the square wave loaded on the phase modulation unit 101, so as to avoid the two detection units being unable to detect the four optical signals.

[0041] In one embodiment, in order to make the subsequent signal processing process more convenient, the optoelectronic hybrid mixer further includes: an attenuation unit, which is used to attenuate the optical signal output by the 2×2 power splitter, so that the powers of the attenuated third optical signal and the fifth optical signal are equal, and the powers of the fourth optical signal and the sixth optical signal are equal. In a specific implementation, the attenuation unit includes an optical attenuator, and specifically, according to the powers of the third optical signal and the fifth optical signal, the optical signal with a larger power can be input to the optical attenuator; for example, if the power of the third optical signal is greater than that of the fifth optical signal, an optical attenuator is set in the optical path where the third optical signal is located, so that the power of the attenuated third optical signal and the unattenuated fifth optical signal is equal. In addition, optical attenuators can also be set in the optical paths where the two output ports of the 2×2 power splitter are located, so that the powers of the attenuated optical signals are equal.

[0042] The embodiment of the present invention also provides a coherent ranging system, such as Figure 4 As shown, the system includes: a signal generating module 201, a data processing module 203 and the optoelectronic hybrid frequency mixing device 202 described in the above embodiment, the signal generating module 201 is used to output a first optical signal and a first detection signal; the optoelectronic hybrid frequency mixing device 202 is used to receive the first optical signal and the second optical signal reflected by the first detection signal through the target to be detected, and obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal and a sixth electrical signal after modulating, mixing and detecting the first optical signal and the second optical signal; the data processing module 203 is used to process and calculate the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal to obtain the distance information of the target to be detected.

[0043] The coherent ranging system provided by the embodiment of the present invention adopts the above-mentioned optoelectronic hybrid mixer 202 to achieve mixing. Compared with the existing mixer for mixing, the structure of the mixer is simplified and the size of the mixer is reduced. In addition, the system is provided with a signal generating module 201 and a data processing module 203, and the detection of the distance of the target to be detected is achieved by processing and calculating the reflected signal of the target to be detected.

[0044] In one embodiment, when the optoelectronic hybrid mixer 202 modulates, mixes, and detects the first optical signal and the second optical signal, the first optical signal, i.e., the local oscillator light or the reference light, may be input to the phase modulation unit 101 for modulation, and then the modulated first optical signal and the unmodulated second optical signal are input to the 2×2 power beam splitter 102 for mixing. In one embodiment, the second optical signal, i.e., the signal light, may also be input to the phase modulation unit 101 for modulation, and then the modulated second optical signal and the unmodulated first optical signal are input to the 2×2 power beam splitter 102 for mixing.

[0045] In one embodiment, if Figure 5 As shown, the signal generating module 201 includes: a light emitting unit 21, a beam splitting unit 22 and an optical transceiver unit 23. The light emitting unit 21 is used to output a laser signal; the beam splitting unit 22 is used to split the laser signal to obtain a first optical signal and a first detection signal; the optical transceiver unit 23 is used to collimate and transmit the first detection signal to the target to be detected, and then output the second optical signal reflected by the target to be detected. In a specific embodiment, the light emitting unit 21 can select a laser, and at the same time, before the light emitted by the light emitting unit 21 is input to the beam splitting unit 22, the light can be modulated by frequency modulation or amplitude chirp modulation. The beam splitting unit 22 can use a beam splitter, and the optical transceiver unit 23 can use optical elements such as lenses to achieve corresponding functions.

[0046] In one embodiment, if Figure 5 As shown, the data processing module 203 includes: a differential amplifier unit 24 and a Fourier unit 25. The differential amplifier unit 24 is used to output the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal after differential amplification; the Fourier unit 25 is used to calculate the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal after differential amplification to obtain the distance information of the target to be detected.

[0047] In one embodiment, if Figure 5 As shown, the coherent ranging system can work according to the following process: the light emitting unit 21 sends a laser signal to the beam splitting unit 22, the beam splitting unit 22 splits the laser signal into a first light signal and a first detection signal, the optical transceiver unit 23 collimates the first detection signal and transmits it to the target to be detected, and receives the second light signal reflected by the target to be detected and outputs it to the 2×2 power beam splitter 102, the phase modulation unit 101 performs phase modulation on the first light signal to obtain a first modulated light signal and outputs it to the 2×2 power beam splitter 102, and the 2×2 power beam splitter 102 combines the first modulated light signal and the first detection signal. After mixing the two optical signals, a third optical signal and a fourth optical signal are output at the first port, and a fifth optical signal and a sixth optical signal are output at the second port. The first detection unit 103 and the second detection unit 104 respectively detect and convert the third optical signal and the fourth optical signal, and the fifth optical signal and the sixth optical signal to obtain a third electrical signal and a fourth electrical signal, and a fifth electrical signal and a sixth electrical signal. The differential amplifier unit 24 differentially amplifies the third electrical signal and the fourth electrical signal, and the fifth electrical signal and the sixth electrical signal, and then inputs them into the Fourier unit 25 for calculation to obtain the distance information of the target to be detected.

[0048] The embodiment of the present invention also provides a coherent ranging method, such as Figure 6 As shown, the coherent ranging method includes the following steps:

[0049] Step S101: the laser signal output by the light-emitting unit is divided into a first light signal and a first detection signal, and the first detection signal is irradiated on the target to be detected and reflected to obtain a second light signal; optionally, the light-emitting unit includes a laser; a beam splitter can be used to divide the laser signal output by the light-emitting unit into the first light signal and the first detection signal; an optical transceiver unit is used to collimate the first detection signal and then transmit it to the target to be detected, and the optical transceiver unit can also receive and output the second light signal reflected back by the target to be detected.

[0050] Step S102: After phase modulating the first optical signal or the second optical signal, mix it with an optical signal that has not been phase modulated to obtain a third optical signal and a fifth optical signal with a low level duration, and a fourth optical signal and a sixth optical signal with a high level duration.

[0051] In one embodiment, the first optical signal, i.e., the local oscillator light or the reference light, can be input into the phase modulation unit for modulation, and then the modulated first optical signal and the unmodulated second optical signal are input into the 2×2 power beam splitter for mixing. At this time, the third optical signal, the fourth optical signal, the fifth optical signal, and the sixth optical signal all include the mixed first modulated optical signal and the second optical signal. In the third optical signal and the fourth optical signal, the phase difference between the mixed first modulated optical signal and the second optical signal is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the mixed first modulated optical signal and the second optical signal is 90 degrees. In one embodiment, the second optical signal, i.e., the signal light, can also be input into the phase modulation unit for modulation, and then the modulated second optical signal and the unmodulated first optical signal are input into the 2×2 power beam splitter for mixing.

[0052] In one embodiment, a square wave signal may be loaded on the phase modulation unit, so that the optical signal modulated by the phase modulation unit undergoes a 90° phase shift or no phase shift. Thus, the phases of the third optical signal and the fourth optical signal output by the 2×2 power beam splitter also undergo periodic changes, that is, during the low level duration, the two output ports of the 2×2 power beam splitter 102 respectively output the third optical signal and the fifth optical signal, and during the high level duration, the two output ports of the 2×2 power beam splitter 102 respectively output the fourth optical signal and the sixth optical signal, wherein the phases of the third optical signal and the fourth optical signal are -90° and 180°, respectively, and the phases of the fifth optical signal and the sixth optical signal are 90° and 0°, respectively.

[0053] Step S103: The third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal are converted by the first detection unit and the second detection unit respectively to obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal and a sixth electrical signal; in one embodiment, for the four optical signals generated by the 2×2 power splitter, the first detection unit and the second detection unit can be used to detect and convert them respectively to obtain the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal.

[0054] In one embodiment, before the detection conversion is performed on the four optical signals, an attenuation unit may be provided on the optical path to attenuate the four optical signals, and make the powers of the attenuated third optical signal and the fifth optical signal equal, and the powers of the fourth optical signal and the sixth optical signal equal. In a specific implementation, the attenuation unit includes an optical attenuator, and specifically, according to the powers of the third optical signal and the fifth optical signal, the optical signal with a larger power may be input into the optical attenuator; for example, if the power of the third optical signal is greater than that of the fifth optical signal, an optical attenuator is provided on the optical path where the third optical signal is located, so that the powers of the attenuated third optical signal and the unattenuated fifth optical signal are equal. In addition, optical attenuators may also be provided on the optical paths where the two output ports of the 2×2 power beam splitter are located, so that the powers of the attenuated optical signals are equal.

[0055] Step S104: The third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal are processed and calculated to obtain the distance information of the target to be detected. In one embodiment, after the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal are detected and obtained, a differential amplification unit can be used to differentially amplify the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal, and then the differentially amplified electrical signal is input to a Fourier unit for Fourier calculation processing to obtain the distance information of the target to be detected.

[0056] The coherent ranging method provided by the embodiment of the present invention, when mixing the first optical signal and the second optical signal, firstly performs periodic phase modulation on the first optical signal or the second optical signal, and then mixes the modulated optical signal with the unmodulated optical signal, thereby reducing the volume of the mixer used. At the same time, the coherent ranging method can obtain the distance information of the target to be detected by processing and calculating the electrical signal after the detection conversion using the Fourier method.

[0057] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the present invention and the scope of protection defined by the appended claims, and such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should readily understand that the order of the process steps may be changed while maintaining the scope of protection of the present invention.

[0058] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufactures, material compositions, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be easily understood by those skilled in the art that the processes, mechanisms, manufactures, material compositions, means, methods or steps that currently exist or will be developed in the future, which perform substantially the same functions as the corresponding embodiments described in the present invention or obtain substantially the same results, can be applied according to the present invention. Therefore, the claims attached to the present invention are intended to include these processes, mechanisms, manufactures, material compositions, means, methods or steps within their scope of protection.

Claims

1. An optoelectronic hybrid frequency mixing device, characterized in that: include: Phase modulation unit and 2×2 power splitter, The phase modulation unit is used to receive a first optical signal, and perform periodic phase modulation on the first optical signal to obtain a first modulated optical signal; The 2×2 power beam splitter is used to receive a second optical signal and the first modulated optical signal, mix the second optical signal and the first modulated optical signal, during a low level duration, the first port of the 2×2 power beam splitter outputs a third optical signal, and the second port of the 2×2 power beam splitter outputs a fifth optical signal, during a high level duration, the first port of the 2×2 power beam splitter outputs a fourth optical signal, and the second port of the 2×2 power beam splitter outputs a sixth optical signal, the third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal all include the first modulated optical signal and the second optical signal after mixing, in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees; The phases of the third optical signal and the fourth optical signal are respectively -90° and 180°, and the phases of the fifth optical signal and the sixth optical signal are respectively 90° and 0°.

2. The optoelectronic hybrid frequency mixing device according to claim 1, characterized in that: Also includes: a first detection unit and a second detection unit, The first detection unit is used to receive the third optical signal and the fourth optical signal, and convert the third optical signal and the fourth optical signal into a third electrical signal and a fourth electrical signal respectively; The second detection unit is used to receive the fifth optical signal and the sixth optical signal, and convert the fifth optical signal and the sixth optical signal into a fifth electrical signal and a sixth electrical signal respectively.

3. The optoelectronic hybrid frequency mixing device according to claim 1, characterized in that: The 2×2 power beam splitter includes any one of a 2×2 multimode interference coupler, a 2×2 directional coupler, a ring cavity coupler, a star coupler, a Fresnel lens array based on a slab waveguide, a super lens array based on a slab waveguide, and a semi-transparent and semi-reflective mirror.

4. The optoelectronic hybrid frequency mixing device according to claim 1, characterized in that: The modulation mechanism of the phase modulation unit includes: any one of photoelectric effect, elastic-optic effect, magneto-optic effect, and phase change effect.

5. The optoelectronic hybrid frequency mixing device according to claim 1, characterized in that: Also includes: An attenuation unit, wherein the attenuation unit is used to attenuate the optical signal output by the 2×2 power beam splitter, so that the powers of the attenuated third optical signal and the fifth optical signal are equal, and the powers of the fourth optical signal and the sixth optical signal are equal.

6. A coherent ranging system, characterized in that: include: A signal generating module, a data processing module and an optoelectronic hybrid frequency mixing device as claimed in any one of claims 2 to 5, The signal generating module is used to output a first optical signal and a first detection signal; The optoelectronic hybrid mixer is used to receive the first optical signal and the second optical signal reflected by the first detection signal through the target to be detected, and to obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal and a sixth electrical signal after modulating, mixing and detecting the first optical signal and the second optical signal; The data processing module is used to process and calculate the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal to obtain the distance information of the target to be detected.

7. The coherent ranging system according to claim 6, characterized in that: The signal generating module comprises: a light emitting unit, a beam splitting unit and an optical transceiver unit. The light emitting unit is used to output a laser signal; The beam splitting unit is used to split the laser signal to obtain a first optical signal and a second detection signal; The optical transceiver unit is used to collimate and transmit the first detection signal to the target to be detected, and then output the second optical signal reflected by the target to be detected.

8. The coherent ranging system according to claim 6, characterized in that: The data processing module includes: a differential amplifier unit and a Fourier unit, The differential amplification unit is used to differentially amplify the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal and then output them; The Fourier unit is used to calculate the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal after differential amplification to obtain the distance information of the target to be detected.

9. A coherent ranging method, characterized in that: include: The laser signal output by the light emitting unit is divided into a first light signal and a first detection signal, wherein the first detection signal is irradiated on the target to be detected and reflected to obtain a second light signal; After phase modulating the first optical signal or the second optical signal, mixing it with an optical signal that has not been phase modulated to obtain a third optical signal and a fifth optical signal with a low level duration, and a fourth optical signal and a sixth optical signal with a high level duration, wherein the third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal all include the first modulated optical signal and the second optical signal after mixing, and in the third optical signal and the fourth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is -90 degrees, and in the fifth optical signal and the sixth optical signal, the phase difference between the first modulated optical signal and the second optical signal after mixing is 90 degrees, and the phases of the third optical signal and the fourth optical signal are -90 degrees and 180 degrees, respectively, and the phases of the fifth optical signal and the sixth optical signal are 90 degrees and 0 degrees, respectively; The third optical signal, the fourth optical signal, the fifth optical signal and the sixth optical signal are converted by the first detection unit and the second detection unit respectively to obtain a third electrical signal, a fourth electrical signal, a fifth electrical signal and a sixth electrical signal; The distance information of the target to be detected is obtained by processing and calculating the third electrical signal, the fourth electrical signal, the fifth electrical signal and the sixth electrical signal.

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