A laser data level detection system

Abstract

The invention discloses a laser data level detection system, comprising a laser driver, a laser, a current mirror, an AC coupling unit, a DC coupling unit, a "1" level detection circuit and a "0" level detection circuit, wherein the laser driver is electrically connected to the laser, the laser comprises a laser generator and a laser receiver, the output end of the laser receiver is electrically connected to the input end of the AC coupling unit, the output end of the AC coupling unit is electrically connected to both the input end of the "1" level detection circuit and the input end of the "0" level detection circuit, the laser receiver is electrically connected to the input end of the DC coupling unit through the current mirror, and the output end of the DC coupling unit is electrically connected to both the input end of the "1" level detection circuit and the input end of the "0" level detection circuit.

Description

Technical Field

[0001] The invention relates to the technical field of level detection, and in particular to a laser data level detection system. Background Art

[0002] In the design of optical modules, the extinction ratio is one of the important parameters to measure the performance of the optical transmission part. If the extinction ratio is too small, it will lead to poor light receiving sensitivity. If the extinction ratio is too large, it will degrade the light transmission eye diagram and also affect the light receiving sensitivity. Therefore, the extinction ratio must be stable within a certain range so that the light receiving sensitivity can reach the best.

[0003] The existing methods for stabilizing the extinction ratio mainly use some temperature compensation technologies. These compensation methods have poor flexibility and are inseparable from temperature acquisition and other links. Compensation after temperature acquisition often requires the use of a large number of equipment and instruments, and the required compensation value must be determined according to the temperature range, and then compensation is performed using a lookup table or potentiometer, which is not conducive to the mass production of optical modules. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a laser data level detection system which has a simple structure and can automatically adjust the laser extinction ratio.

[0005] The technical solution of the present invention is as follows:

[0006] A laser data level detection system comprises an electrically connected laser driver, a laser, a current mirror, an AC coupling unit, a DC coupling unit, a "1" level detection circuit and a "0" level detection circuit, wherein the laser comprises a laser generator and a laser receiver, and the laser is used to generate and output a PD current; the output end of the laser receiver is electrically connected to the input end of the AC coupling unit, the output end of the AC coupling unit is electrically connected to an input end of the "1" level detection circuit and an input end of the "0" level detection circuit, and the AC coupling unit is used to extract the AC component of the PD current and send it to the "1" level detection circuit and the "0" level detection circuit; the laser driver comprises a laser generator and a laser receiver, and the laser is used to generate and output a PD current; the output end of the laser receiver is electrically connected to the input end of the AC coupling unit, the output end of the AC coupling unit is electrically connected to an input end of the "1" level detection circuit and an input end of the "0" level detection circuit, and the AC coupling unit is used to extract the AC component of the PD current and send it to the "1" level detection circuit and the "0" level detection circuit; The receiver is also electrically connected to the input end of the DC coupling unit through the current mirror, and the output end of the DC coupling unit is electrically connected to the other input end of the "1" level detection circuit and the other input end of the "0" level detection circuit. The current mirror is used to proportionally copy the PD current, and then the DC coupling unit extracts the DC component of the PD current and sends it to the "1" level detection circuit and the "0" level detection circuit. The "1" level detection circuit is used to detect the potential difference between the data "1" and the DC component in the PD current and obtain the level corresponding to the data "1", and the "0" level detection circuit is used to detect the potential difference between the data "0" and the DC component in the PD current and obtain the level value corresponding to the data "0".

[0007] Furthermore, the "1" level detection circuit includes a diode D1, a capacitor C1, a diode D2, a resistor R1 and a resistor R0, the anode of the diode D1 is electrically connected to the output end of the AC coupling unit, the cathode of the diode D1 is electrically connected to one end of the capacitor C1, the other end of the capacitor C1 is grounded through the resistor R0, the anode of the diode D2 is electrically connected between the cathode of the diode D1 and the capacitor C1, the cathode of the diode D2 is electrically connected to one end of the resistor R1, the other end of the resistor R1 is electrically connected between the capacitor C1 and the resistor R0, and the output end of the DC coupling unit is electrically connected between the capacitor C1 and the resistor R0.

[0008] Furthermore, the "0" level detection circuit includes a diode D3, a capacitor C2, a diode D4, a resistor R2 and a resistor R3, the output end of the AC coupling unit is electrically connected to the cathode of the diode D3, the cathode of the diode D3 is also grounded through the resistor R3, the anode of the diode D3 is electrically connected to one end of the capacitor C2, the other end of the capacitor C2 is electrically connected to the output end of the DC coupling unit, the anode of the diode D4 is electrically connected between the capacitor C2 and the output end of the DC coupling unit, the cathode of the diode D4 is electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected between the capacitor C2 and the anode of the diode D3.

[0009] Furthermore, the laser generator is a laser diode.

[0010] Furthermore, the laser receiver is a photodiode.

[0011] Beneficial effect: In the present invention, the AC component of the laser receiver current is extracted by the AC coupling unit, and the DC component of the laser receiver current is extracted by the DC coupling unit. The "1" level circuit detects the potential difference between the data "1" and the DC component and obtains the level of the data "1". The "0" level circuit detects the potential difference between the DC component and the data "0" and obtains the level of the data "0". The real-time extinction ratio of the laser is detected, and the extinction ratio is automatically adjusted to achieve a stable extinction ratio and improve the quality and reliability of optical communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of a preferred implementation of a laser data level detection system of the present invention. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with the accompanying drawings.

[0014] In the description of the present invention, unless otherwise specified and limited, it should be noted that the term "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two elements. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0015] like Figure 1 As shown, a laser data level detection system of the present invention includes a laser driver 1 and a laser 2, wherein the laser driver 1 is electrically connected to the laser 2, and the laser 2 includes a laser generator 21 and a laser receiver 22, wherein the laser generator 21 is a laser diode, and the laser receiver 22 is a photodiode. The laser driver 1 drives the laser diode to emit light, and the photodiode detects and outputs PD current.

[0016] The laser data level detection system further includes a current mirror 3, an AC coupling unit 4, a DC coupling unit 5, a "1" level detection circuit 6 and a "0" level detection circuit 7. The output end of the laser receiver 22 is electrically connected to the input end of the AC coupling unit 4, and the output end of the AC coupling unit 4 is electrically connected to the input end of the "1" level detection circuit 6 and the input end of the "0" level detection circuit 7. The AC coupling unit 4 is used to extract the AC component of the PD current and send it to the "1" level detection circuit 6 and the "0" level detection circuit 7. The laser receiver 22 is connected to the DC coupling unit 5 through the current mirror 3. The input end is electrically connected, the output end of the DC coupling unit 5 is electrically connected to the input end of the "1" level detection circuit 6 and the input end of the "0" level detection circuit 7, the current mirror 3 is used to proportionally copy the PD current, and then the DC coupling unit 5 extracts the DC component of the PD current and sends it to the "1" level detection circuit 6 and the "0" level detection circuit 7, the "1" level detection circuit 6 is used to detect the potential difference between the data "1" and the DC component in the PD current and obtain the level corresponding to the data "1", and the "0" level detection circuit 7 is used to detect the potential difference between the data "0" and the DC component in the PD current and obtain the level value of the data "0".

[0017] The "1" level detection circuit 6 includes a diode D1, a capacitor C1, a diode D2, a resistor R1 and a resistor R0. The anode of the diode D1 is electrically connected to the output end of the AC coupling unit 4, the cathode of the diode D1 is electrically connected to one end of the capacitor C1, the other end of the capacitor C1 is grounded through the resistor R0, the anode of the diode D2 is electrically connected between the cathode of the diode D1 and the capacitor C1, the cathode of the diode D2 is electrically connected to one end of the resistor R1, the other end of the resistor R1 is electrically connected between the capacitor C1 and the resistor R0, and the output end of the DC coupling unit 5 is electrically connected between the capacitor C1 and the resistor R0. When the data sent by the laser 2 is "1", the "1" level detection circuit 6 is used to detect the level corresponding to the data "1", and the "0" level detection circuit 7 does not work at this time.

[0018] The "0" level detection circuit 7 includes a diode D3, a capacitor C2, a diode D4, a resistor R2 and a resistor R3. The output end of the AC coupling unit 4 is electrically connected to the cathode of the diode D3, and the cathode of the diode D3 is also grounded through the resistor R3. The anode of the diode D3 is electrically connected to one end of the capacitor C2, and the other end of the capacitor C2 is electrically connected to the output end of the DC coupling unit 5. The anode of the diode D4 is electrically connected between the capacitor C2 and the output end of the DC coupling unit 5. The cathode of the diode D4 is electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected between the capacitor C2 and the anode of the diode D3. When the data sent by the laser 2 is "0", the "0" level detection circuit 7 is used to detect the level corresponding to the data "0", and at this time, the "1" level detection circuit 6 does not work.

[0019] The working principle of this embodiment is as follows:

[0020] In the design of optical modules, the so-called extinction ratio (Extinction, Ex) refers to the ratio of the optical power of laser 2 when sending all "1" codes to the optical power when sending all "0" codes. It reflects the signal distinction between laser 2 sending data "1" and data "0". The optical power when data "1" is defined as P1 and the optical power when data "0" is defined as P0. The extinction ratio (Extinction, Ex) can be expressed as:

[0021]

[0022] The output light of laser 2 has a stable linear relationship with its PD current, and this relationship can be maintained over a wide temperature range. For the optical module, it is only necessary to maintain the PD current I m1 The PD current I m0The purpose of stabilizing the extinction ratio can be achieved if the ratio of is stable. That is:

[0023]

[0024] To this end, the present invention proposes a laser data level detection system, which aims to calculate the I in the above formula ② by real-time detection of the levels of data "1" and data "0". m1 with I m0 The ratio of , thus obtaining the output extinction ratio of laser 2.

[0025] like Figure 1 As shown, the laser driver 1 first drives the laser diode 21 to emit light, and the photodiode 22 detects the light source of the laser diode 21, converts the optical signal into an electrical signal, and then outputs a PD current and sends it to the current mirror 3 and the AC coupling unit 4. The current mirror 3 proportionally copies the PD current and sends it to the DC coupling unit 5. The AC coupling unit 4 extracts the AC component of the PD current and sends it to the "1" level detection circuit 6 and the "0" level detection circuit 7. The DC coupling unit 5 extracts the DC component of the PD current and sends it to the "1" level detection circuit 6 and the "0" level detection circuit 7.

[0026] When the data sent by laser 2 is "1", Figure 1 The potential of point A is higher than that of point B, that is, the potential difference between point A and point B is V AB >0, diode D1 conducts unidirectionally to charge capacitor C1, and the corresponding level is maintained after charging is completed. If V AB If V AB If the voltage becomes smaller, it will discharge through the unidirectional discharge circuit composed of diode D2, resistor R1 and resistor R0, and then maintain the corresponding level. Figure 1 The potential of point B is lower than that of point C, that is, the potential difference between point B and point C is V BC <0, diode D3 and diode D4 are both off, "0" level detection circuit 7 does not work, and V can be tracked in real time during the process of capacitor C1 charging, discharging and holding. AB , when V AB When changes occur Figure 1 The voltage V at point D to ground D will also change accordingly to detect the data "1" level, that is, V D .

[0027] When the data sent by laser 2 is "0", Figure 1 The potential of point B is higher than that of point C, that is, the potential difference between point B and point C is V BC >0, diode D3 conducts unidirectionally to charge capacitor C2, and maintains the corresponding level after charging is completed. If VBC If V BC If the voltage becomes smaller, it will discharge through the unidirectional discharge circuit composed of diode D4, resistor R2 and resistor R3, and then maintain the corresponding level. Figure 1 The potential of point A is lower than that of point B, that is, the potential difference between point A and point B is V AB <0, diode D1 and diode D2 are both off, "1" level detection circuit 6 does not work, and V can be tracked in real time during the process of capacitor C2 charging, discharging and holding. BC , when V BC When changes occur Figure 1 The voltage V at point E to ground E will also change accordingly to achieve the detection of the data "0" level, that is, V E .

[0028] The level V of the above data "1" D and data "0" level V E The specific value can be obtained through ADC sampling, so the PD current I of data "1" m1 The PD current I m0 The ratio is:

[0029]

[0030] When R3=R0, according to ③, we can conclude that:

[0031]

[0032] According to ①②③④, the output extinction ratio of the laser can be calculated:

[0033]

[0034] The present invention is implemented based on the theories of current replication of a current mirror 3, unidirectional conduction of a diode, and charging, discharging, and holding of a capacitor. First, the laser PD current is proportionally replicated by the current mirror 3 to form two identical PD currents. Then, an AC coupling unit 4 is used to extract the AC component of one PD current, and a DC coupling unit 5 is used to extract the DC component of the other PD current. Then, a "1" level detection circuit 6 is used to detect the potential difference between data "1" and the DC component in the PD current to obtain the level of data "1", and a "0" level detection circuit 7 is used to detect the potential difference between the DC component and data "0" in the PD current to obtain the level of data "0". The real-time extinction ratio of the laser 2 is detected to realize automatic adjustment of the extinction ratio, so as to achieve a stable extinction ratio and improve the quality and reliability of optical communication.

[0035] The above are only implementation modes of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure made using the contents of the present invention's specification and drawings, directly or indirectly used in other related technical fields, are also within the patent protection scope of the present invention.

Claims

1. A laser data level detection system, comprising a laser driver (1) and a laser (2) electrically connected, wherein the laser (2) comprises a laser generator (21) and a laser receiver (22), and wherein the laser (2) is used to generate and output a PD current, and wherein: The laser data level detection system further comprises a current mirror (3), an AC coupling unit (4), a DC coupling unit (5), a "1" level detection circuit (6) and a "0" level detection circuit (7); the output end of the laser receiver (22) is electrically connected to the input end of the AC coupling unit (4), the output end of the AC coupling unit (4) is electrically connected to an input end of the "1" level detection circuit (6) and an input end of the "0" level detection circuit (7), the AC coupling unit (4) is used to extract the AC component of the PD current and send it to the "1" level detection circuit (6) and the "0" level detection circuit (7); the laser receiver (22) is also electrically connected to the DC coupling unit (5) through the current mirror (3) The input end of the unit (5) is electrically connected, the output end of the DC coupling unit (5) is electrically connected to the other input end of the "1" level detection circuit (6) and the other input end of the "0" level detection circuit (7), the current mirror (3) is used to proportionally copy the PD current, and then the DC coupling unit (5) extracts the DC component of the PD current and sends it to the "1" level detection circuit (6) and the "0" level detection circuit (7), the "1" level detection circuit (6) is used to detect the potential difference between the data "1" and the DC component in the PD current and obtain the level corresponding to the data "1", and the "0" level detection circuit (7) is used to detect the potential difference between the data "0" and the DC component in the PD current and obtain the level value corresponding to the data "0"; The "1" level detection circuit (6) comprises a diode D1, a capacitor C1, a diode D2, a resistor R1 and a resistor R0, wherein the anode of the diode D1 is electrically connected to the output end of the AC coupling unit (4), the cathode of the diode D1 is electrically connected to one end of the capacitor C1, the other end of the capacitor C1 is grounded through the resistor R0, the anode of the diode D2 is electrically connected between the cathode of the diode D1 and the capacitor C1, the cathode of the diode D2 is electrically connected to one end of the resistor R1, the other end of the resistor R1 is electrically connected between the capacitor C1 and the resistor R0, and the output end of the DC coupling unit (5) is electrically connected between the capacitor C1 and the resistor R0; the " The 0" level detection circuit (7) comprises a diode D3, a capacitor C2, a diode D4, a resistor R2 and a resistor R3, the output end of the AC coupling unit (4) is electrically connected to the cathode of the diode D3, the cathode of the diode D3 is also grounded through the resistor R3, the anode of the diode D3 is electrically connected to one end of the capacitor C2, the other end of the capacitor C2 is electrically connected to the output end of the DC coupling unit (5), the anode of the diode D4 is electrically connected between the capacitor C2 and the output end of the DC coupling unit (5), the cathode of the diode D4 is electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected between the capacitor C2 and the anode of the diode D3.

2. A laser data level detection system according to claim 1, characterized in that: The laser generator (21) is a laser diode.

3. A laser data level detection system according to claim 1, characterized in that: The laser receiver (22) is a photodiode.

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