Laser wavelength control circuit and laser

Abstract

An embodiment of the present invention discloses a laser wavelength control circuit and a laser. The circuit includes: a TEC connected to the laser; a temperature monitoring unit connected to the laser; a PID control unit connected to the temperature monitoring unit; a first comparison unit, wherein a first input end of the first comparison unit is connected to the PID control unit; a second comparison unit, wherein a first output end of the second comparison unit is respectively connected to the first input end of the first comparison unit and the PID control unit, a second output end of the second comparison unit is respectively connected to the second input end of the first comparison unit and the PID control unit, and a TEC current is input to the second input end; a first switch unit is respectively connected to the output end of the first comparison unit and the second end of the TEC and is connected to an input voltage Vin; and a second switch unit is respectively connected to the first end of the TEC and the first input end of the second comparison unit and is connected to the input voltage Vin, thereby achieving stable control of the laser wavelength.

Description

Technical Field

[0001] The present invention relates to the technical field of laser wavelength control, and in particular to a laser wavelength control circuit and a laser. Background Art

[0002] Since the birth of the world's first ruby laser in the early 1860s, laser devices and laser technology have developed rapidly. Currently, lasers have penetrated into fields such as industry, agriculture, medicine, national defense, and science and technology, and are showing an increasingly broad development prospect.

[0003] Currently, there are two methods for controlling laser wavelength. The first is to control the laser wavelength by controlling the laser resonant cavity through piezoelectric ceramics. Although this method can control the laser cavity length change within a certain range and make the laser output frequency uniform and stable, this control method has the displacement hysteresis nonlinearity and creep effect of the piezoelectric ceramics, which greatly affects its scanning accuracy and requires precise control of the scanning displacement of the piezoelectric ceramics. In addition, the driving voltage of the piezoelectric ceramic device is relatively high and the step size is very small. Due to the influence of the power supply, it is difficult to control in actual operation, which can easily lead to unstable wavelength control. The second method is to control the laser wavelength through temperature regulation. However, this method cannot accurately control the heating and cooling current of the laser, resulting in the inability to accurately control the laser wavelength. Therefore, how to stably control the laser wavelength is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a laser wavelength control circuit and a laser, aiming to solve the technical problem in the prior art that the laser wavelength cannot be stably controlled.

[0005] In a first aspect, an embodiment of the present invention provides a laser wavelength control circuit, comprising:

[0006] TEC, the TEC is connected to the laser and is used to heat or cool the laser to control the wavelength of the laser;

[0007] A temperature monitoring unit, connected to the laser and used to monitor the real-time temperature of the laser;

[0008] A PID control unit, connected to the temperature monitoring unit and used to control the current direction and current magnitude of the TEC;

[0009] a first comparing unit, wherein a first input terminal of the first comparing unit is connected to the PID control unit;

[0010] a second comparing unit, wherein a first output end of the second comparing unit is connected to the first input end of the first comparing unit and the PID control unit respectively, a second output end of the second comparing unit is connected to the second input end of the first comparing unit and the PID control unit respectively, and a second input end thereof is input with a TEC current;

[0011] a first switch unit, the first switch unit being connected to the output terminal of the first comparison unit and the second terminal of the TEC respectively, and being connected to an input voltage Vin;

[0012] The second switch unit is connected to the first end of the TEC and the first input end of the second comparison unit respectively, and is connected to the input voltage Vin.

[0013] Preferably, in the laser wavelength control circuit, the PID control unit includes a temperature voltage generating unit and an error proportional voltage generating unit;

[0014] The temperature voltage generating unit is connected to the temperature monitoring unit and the error proportional voltage generating unit respectively, and the error proportional voltage generating unit is connected to the first input terminal of the first comparing unit.

[0015] More preferably, in the laser wavelength control circuit, the temperature voltage generating unit includes an amplifier U1 and a feedback resistor Rf;

[0016] Among them, the positive input end of the amplifier U1 is connected to the temperature monitoring unit, and is connected to the reference voltage Vref, and is connected to the output end of the amplifier U1 through the feedback resistor Rf. The negative input end of the amplifier U1 is connected to half of the reference voltage Vref, and the output end of the amplifier U1 is connected to the error proportional voltage generating unit.

[0017] More preferably, in the laser wavelength control circuit, the error proportional voltage generating unit includes an amplifier U2 and a resistor R4;

[0018] The positive input of the amplifier U2 is connected to the output of the amplifier U1 and to the output of the amplifier U2 through the resistor R4. The negative input of the amplifier U2 is connected to the target temperature voltage Vtemp of the laser. The output of the amplifier U2 is connected to the first input of the first comparison unit.

[0019] Preferably, in the laser wavelength control circuit, the first comparison unit includes a comparator U7, and the second comparison unit includes a comparator U10;

[0020] Among them, the positive input end of the comparator U7 is connected to the PID control unit and the first output end of the comparator U10 respectively, and the negative input end is connected to the second output end of the comparator U10; the positive input end of the comparator U10 is connected to the second switch unit, and the negative input end inputs the TEC current.

[0021] Preferably, in the laser wavelength control circuit, the first switch unit includes a MOS transistor Q1, and the second switch unit includes a MOS transistor Q2;

[0022] The gate of the MOS transistor Q1 is connected to the output end of the first comparison unit, the source is connected to the second end of the TEC, and the drain is connected to the input voltage Vin; the gate of the MOS transistor Q2 is connected to the input end of the second comparison unit, the source is connected to the input voltage Vin, and the drain is connected to the first end of the TEC.

[0023] Preferably, in the laser wavelength control circuit, the circuit further includes an amplifier U5 and an amplifier U6;

[0024] Among them, the non-inverting input end of the amplifier U5 is respectively connected to the PID control unit and the first input end of the first comparison unit, and is connected to the reference voltage Vref through the resistor R11. The reverse input end is connected to the output end of the amplifier U5 through the resistor R13 and the resistor R14 in sequence, and the output end of the amplifier U5 outputs the TEC voltage; the non-inverting input end of the amplifier U6 is respectively connected to the first input end of the second comparison unit and the second switch unit, and the reverse input end is respectively connected to the second input end of the second comparison unit and the output end of the amplifier U6 through the resistor R18, and the output end of the amplifier U6 outputs the TEC current.

[0025] Preferably, in the laser wavelength control circuit, the circuit further includes an amplifier U3 and an amplifier U4;

[0026] Among them, the non-inverting input terminal of the amplifier U3 is connected to the PID control unit, the reverse input terminal is connected to the output terminal of the amplifier U3 through the resistor R8, and is connected to the reference voltage Vref through the resistor R9, the output terminal of the amplifier U3 is connected to the non-inverting input terminal of the amplifier U4 through the resistor R7; the reverse input terminal of the amplifier U4 is connected to the power supply voltage VDD, and the output terminal is connected to the first input terminal of the first comparison unit.

[0027] Preferably, in the laser wavelength control circuit, the circuit further includes a switch S1, a comparator U9, a switch S2, an amplifier U8 and a NOT gate;

[0028] Among them, the first end of the switch S1 is connected to the first output end of the second comparison unit, the second end is connected to the power supply voltage VDD, and the third end is connected to the inverting input end of the amplifier U8; the non-inverting input end of the amplifier U8 inputs the TEC current, and the output end is respectively connected to the PID control unit and the first input end of the first comparison unit; the first end of the switch S2 is connected to the second output end of the second comparison unit, and the second end is respectively connected to the non-inverting input end of the comparator U9, the PID control unit, the output end of the amplifier U8 and the first input end of the first comparison unit; the inverting input end of the comparator U9 is connected to the power supply voltage VCC, and the output end is connected to the first input end of the NOT gate; the second input end of the NOT gate is connected to the enable signal, and the output end is connected to the second input end of the first comparison unit.

[0029] In a second aspect, an embodiment of the present invention further provides a laser, which includes a laser body and the laser wavelength control circuit described in the first aspect.

[0030] Compared with the prior art, the embodiments of the present invention provide a laser wavelength control circuit and a laser. The PID control unit in the circuit monitors the real-time temperature of the laser and the temperature when the laser outputs a preset wavelength through a monitoring unit to generate an error proportional voltage required for the laser to stably output the preset wavelength, and turns on and off the first switching unit and the second switching unit through the first comparison unit and the second comparison unit, thereby changing the current direction and magnitude of the TEC to control the heating or cooling of the TEC, thereby achieving heating or cooling of the laser to stabilize to the preset temperature of the laser, thereby enabling the laser to stably output the preset wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A schematic block diagram of a laser wavelength control circuit provided by an embodiment of the present invention;

[0033] Figure 2 A circuit diagram of a temperature voltage generating unit in a PID control unit provided in an embodiment of the present invention;

[0034] Figure 3 A circuit diagram of an error proportional voltage generating unit in a PID control unit provided by an embodiment of the present invention;

[0035] Figure 4This is a schematic diagram of a laser wavelength control circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0038] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in the specification and appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0039] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0040] See also Figure 1 As shown, Figure 1 Schematic block diagram of the laser wavelength control circuit provided by the embodiment of the present invention. Figure 1 As shown, a laser wavelength control circuit includes:

[0041] TEC, the TEC is connected to the laser and is used to heat or cool the laser to control the wavelength of the laser;

[0042] A temperature monitoring unit 10 is connected to the laser and is used to monitor the real-time temperature of the laser;

[0043] A PID control unit 20 , connected to the temperature monitoring unit 10 and configured to control the current direction and magnitude of the TEC;

[0044] a first comparing unit 30, wherein a first input terminal of the first comparing unit 30 is connected to the PID control unit 20;

[0045] a second comparing unit 40, wherein a first output terminal of the second comparing unit 40 is connected to a first input terminal of the first comparing unit 30 and the PID control unit 20, respectively; a second output terminal of the second comparing unit 40 is connected to a second input terminal of the first comparing unit 30 and the PID control unit 20, respectively; and a second input terminal outputs a TEC current;

[0046] a first switch unit 50 , wherein the first switch unit 50 is connected to the output terminal of the first comparison unit 30 and the second terminal of the TEC, and is connected to an input voltage Vin;

[0047] The second switch unit 60 is connected to the first end of the TEC and the first input end of the second comparison unit 40 respectively, and is connected to the input voltage Vin.

[0048] Among them, the PID control unit 20 generates a voltage corresponding to the real-time temperature based on the real-time temperature monitored by the temperature monitoring unit 10, and generates an error proportional voltage based on the voltage and the target temperature voltage Vtemp corresponding to the preset temperature of the laser. The first comparison unit 30 and the second comparison unit 40 control the conduction and shutdown of the first switch unit 50 and the second switch unit 60 through the error proportional voltage, thereby controlling the current direction and size of the TEC to heat or cool the TEC, thereby stabilizing the wavelength of the laser.

[0049] Specifically, in this embodiment, the first end of the TEC is the positive electrode, and the second end is the negative electrode. When the current in the TEC flows from the first end to the second end, the first switch unit 50 is disconnected and the second switch unit 60 is connected, and the TEC heats the laser. When the current in the TEC flows from the second end to the first end, the first switch unit 50 is connected and the second switch unit 60 is disconnected, and the TEC cools the laser.

[0050] In an embodiment of the present invention, the wavelength of the laser, the temperature of the laser, and the voltage corresponding to the temperature have a one-to-one correspondence. Different wavelengths correspond to different temperatures. When the temperature of the laser changes, the wavelength of the laser will drift. Therefore, the present application controls the current direction and magnitude of the TEC by generating an error proportional voltage to heat or cool the TEC, thereby stabilizing the wavelength of the laser at a preset temperature.

[0051] In some embodiments, the temperature monitoring unit 10 includes a thermistor Rth. One end of the thermistor Rth is grounded, and the other end is connected to the PID control unit 20 and to a reference voltage Vref. Specifically, the laser diode, TEC, and thermistor Rth are packaged in a laser diode module. The TEC heats or cools the laser diode. Similarly, the thermistor Rth monitors the real-time temperature of the laser diode.

[0052] Among them, TEC (Thermo Electric Cooler) is made by using the Peltier effect of semiconductor materials, and the thermistor Rth can be a temperature resistor with a negative temperature coefficient (NTC) or a temperature resistor with a positive temperature coefficient (RTD). There is no specific limitation in this embodiment, and it can be selected according to specific practical applications.

[0053] In some embodiments, the PID control unit 20 includes a temperature voltage generating unit and an error proportional voltage generating unit; wherein the temperature voltage generating unit is connected to the temperature monitoring unit 10 and the error proportional voltage generating unit, respectively, and the error proportional voltage generating unit is connected to the first input terminal of the first comparison unit 30. Specifically, the temperature voltage generating unit is configured to receive the real-time temperature of the temperature monitoring unit 10 and convert the real-time temperature into a linear voltage that is proportional to the real-time temperature of the laser. After receiving the linear voltage, the error proportional voltage generating unit compares it with the target temperature voltage Vtemp corresponding to the preset wavelength of the laser to generate an error proportional voltage, thereby turning on and off the first switch unit 50 and the second switch unit 60, thereby heating or cooling the TEC and stabilizing the wavelength of the laser.

[0054] In some specific embodiments, such as Figure 2 As shown, the temperature voltage generating unit includes an amplifier U1 and a feedback resistor Rf; wherein, the positive input terminal of the amplifier U1 is connected to the temperature monitoring unit 10, and is connected to the reference voltage Vref, and is connected to the output terminal of the amplifier U1 through the feedback resistor Rf, the negative input terminal of the amplifier U1 is connected to half of the reference voltage Vref, and the output terminal of the amplifier U1 is connected to the error proportional voltage generating unit.

[0055] Specifically, in Figure 2 In the embodiment shown, the temperature voltage generating unit further includes a voltage divider circuit including resistors R1 and R2. The positive input terminal of the amplifier U1 is connected to the thermistor Rth through the resistor R1 and is connected to the reference voltage Vref through the resistor R2.

[0056] The voltage Vout1 outputted from the output terminal of the amplifier U1 is expressed as follows:

[0057]

[0058] In some specific embodiments, such as Figure 3 As shown, the error proportional voltage generating unit includes an amplifier U2 and a resistor R4; wherein, the positive input terminal of the amplifier U2 is connected to the output terminal of the amplifier U1, and is connected to the output terminal of the amplifier U2 through the resistor R4,, the reverse input terminal of the amplifier U2 is connected to the target temperature voltage Vtemp of the laser, and the output terminal of the amplifier U2 is connected to the first input terminal of the first comparison unit 30.

[0059] Specifically, in Figure 3 In the embodiment shown, the positive input terminal of the amplifier U2 is connected to the output terminal of the amplifier U1 through the resistor R3. The target temperature voltage Vtemp is the voltage corresponding to the preset wavelength of the laser. The target temperature voltage Vtemp can be output through the DA input of the external microcontroller or through a digital potentiometer.

[0060] The voltage Vout2 outputted from the output terminal of the amplifier U2 is expressed as follows:

[0061]

[0062] Wherein: Z1 is the impedance of resistor R3, and Z2 is the impedance of resistor R4.

[0063] In some embodiments, as Figure 4As shown, the first comparison unit 30 includes a comparator U7, and the second comparison unit 40 includes a comparator U10; wherein the positive input terminal of the comparator U7 is connected to the PID control unit 20 and the first output terminal of the comparator U10 respectively, and the negative input terminal is connected to the second output terminal of the comparator U10; the positive input terminal of the comparator U10 is connected to the second switch unit 60, and the negative input terminal inputs the TEC current; the first switch unit 50 includes a MOS transistor Q1, and the second switch unit 60 includes a MOS transistor Q2; wherein the gate of the MOS transistor Q1 is connected to the output terminal of the first comparison unit 30, the source is connected to the second terminal of the TEC, and the drain is connected to the input voltage Vin; the gate of the MOS transistor Q2 is connected to the input terminal of the second comparison unit 40, the source is connected to the input voltage Vin, and the drain is connected to the first terminal of the TEC. Specifically, the voltage across the TEC is monitored by the feedback terminal and the output terminal of the TEC. The feedback terminal of the TEC is the second terminal of the TEC, and the output terminal of the TEC is the first terminal of the TEC. The operating voltage across the TEC is the same, but the operating current across the TEC is different, and their working methods are also different. The mathematical expression is:

[0064] TEC output voltage = VB - 40 * (Vout2 - 1.25V)

[0065] TEC feedback voltage = TEC output voltage + 5 (Vout2 - 1.25V)

[0066] Among them: when the operating voltage across the TEC is less than 4.0V, VB = 1.5V; when the operating voltage across the TEC is greater than 4.0V, VB = 2.5V.

[0067] In addition, when the laser wavelength control circuit reaches a stable state, the output Vout2 of the amplifier U2 reaches the target setting value, and the control circuit automatically outputs a hysteresis voltage between 1.45V and 1.55. If it is lower than 1.45 or higher than 1.55, it will automatically control the TEC heating or cooling.

[0068] exist Figure 4In the illustrated embodiment, MOS transistor Q1 is an N-type MOS transistor, and MOS transistor Q2 is a P-type MOS transistor. A body diode is connected between the source and drain of MOS transistors Q1 and Q2. The circuit also includes amplifiers U3 and U4. The non-inverting input of amplifier U3 is connected to the output of amplifier U2 via resistor R5, the inverting input is connected to the output of amplifier U3 via resistor R8, and is connected to a reference voltage Vref via resistor R9. The output of amplifier U3 is connected to the non-inverting input of amplifier U4 via resistor R7. The inverting input of amplifier U4 is connected to power supply voltage VDD, and the output is connected to the non-inverting input of comparator U7. Specifically, amplifier U3, resistors R8, and R9 form a negative feedback amplifier circuit, and amplifier U4, resistors R15, R16, R17, capacitors C1, C2, and C3 form a negative feedback amplifier circuit, thereby quickly stabilizing the laser wavelength and improving the accuracy of the stabilization of the laser wavelength.

[0069] In some embodiments, as Figure 4 As shown, the circuit further includes an amplifier U5 and an amplifier U6; wherein, the non-inverting input terminal of the amplifier U5 is respectively connected to the PID control unit 20 and the first input terminal of the first comparison unit 30, and is connected to the reference voltage Vref through the resistor R11, and is sequentially connected to the output terminal of the amplifier U3 through the resistor R12, the resistor R10 and the resistor R7, and the reverse input terminal is sequentially connected to the output terminal of the amplifier U5 through the resistor R13 and the resistor R14, and the output terminal of the amplifier U5 outputs the TEC voltage; the non-inverting input terminal of the amplifier U6 is respectively connected to the non-inverting input terminal of the comparator U10 and the gate of the MOS tube, and the reverse input terminal is respectively connected to the reverse input terminal of the comparator U10 and the output terminal of the amplifier U6 through the resistor R18, and the output terminal of the amplifier U6 outputs the TEC current.

[0070] Specifically, amplifier U5, resistors R13, and R14 form a negative feedback amplifier circuit for high-voltage protection of the TEC, while amplifier U6 and resistor R18 form a negative feedback amplifier circuit for overcurrent protection of the TEC. The TEC voltage output by amplifier U5 simulates the voltage across the TEC and is proportional to the voltage across the TEC. A center voltage of 1.25V corresponds to a 0V voltage of the TEC. The TEC voltage Vtec is calculated as: Vtec = 1.25 + 0.25 * (TEC output voltage - TEC feedback voltage). The TEC feedback voltage is the voltage between the source of MOS transistor Q1 and the second terminal of the TEC, and the TEC output voltage is the voltage between the drain of MOS transistor Q2 and the first terminal of the TEC.

[0071] The TEC current output from the output end of amplifier U6 is the current of the simulated TEC, which is proportional to the actual current Itec flowing through the TEC. The center voltage of 1.25V corresponds to the voltage output by the TEC's 0A current, and the current flowing through the TEC can be calculated using the following formula: Vset = 1.25V-Itec*R, where Vset is the voltage corresponding to the TEC current, and R is the resistance at the actual current Itec on the TEC.

[0072] Furthermore, to ensure that the TEC's heating or cooling operates within its normal operating range, the heating or cooling voltage must be limited. When heating current flows through the TEC, the internal current sink connected to the voltage limiting voltage sinks current, effectively lowering the TEC's limiting voltage. When cooling current drives the TEC, the current sink is ineffective, so the heating voltage is always lower than the cooling voltage. When the TEC voltage Vtec is 2.5V, the maximum TEC voltage limit must not exceed 1.2V. The maximum voltage setting corresponding to the TEC current must be greater than 1.3V to ensure the TEC has an appropriate margin between heating and cooling.

[0073] exist Figure 4 In the embodiment shown, the circuit further includes a switch S1, a comparator U9, a switch S2, an amplifier U8 and a NOT gate; wherein the first end of the switch S1 is connected to the first output end of the second comparison unit 40, the second end is connected to the power supply voltage VDD, and the third end is connected to the inverting input end of the amplifier U8; the non-inverting input end of the amplifier U8 inputs the TEC current, and the output end is respectively connected to the first input end of the PID control unit 20 and the first comparison unit 30; the first end of the switch S2 is connected to the second output end of the second comparison unit 40, and the second end is respectively connected to the non-inverting input end of the comparator U9, the PID control unit 20, the output end of the amplifier U8 and the first input end of the first comparison unit 30; the inverting input end of the comparator U9 is connected to the power supply voltage VCC, and the output end is connected to the first input end of the NOT gate; the second input end of the NOT gate is connected to the enable signal, and the output end is connected to the second input end of the first comparison unit 30.

[0074] Specifically, when the first output end of the comparator U10 generates a cooling signal, the first end of the switch S1 is connected to the third end, the first end of the switch S2 is disconnected from the second end, the output end of the comparator U7 is at a high level, the MOS tube Q1 is turned on, and the MOS tube Q2 is not turned on. At this time, the current on the TEC flows from the second end to the first end, and the TEC starts the cooling mode; when the second output end of the comparator U10 generates a heating signal, the first end of the switch S1 is connected to the second end, the first end of the switch S2 is connected to the second end, the output end of the comparator U7 is at a low level, the MOS tube Q1 is not turned on, and the MOS tube Q2 is turned on. At this time, the current on the TEC flows from the first end to the second end, and the TEC starts the heating mode.

[0075] In some embodiments, the present invention further provides a laser, which includes a laser body and the above-mentioned laser wavelength control circuit to lock the laser wavelength and ensure that the device operates within a normal current range.

[0076] An embodiment of the present invention provides a laser wavelength control circuit and a laser, the circuit comprising a TEC, a temperature monitoring unit 10, a PID control unit 20, a first comparison unit 30, a second comparison unit 40, a first switch unit 50, and a second switch unit 60; wherein the TEC is connected to the laser, the temperature monitoring unit 10 is connected to the laser, the PID control unit 20 is connected to the temperature monitoring unit 10, the first input end of the first comparison unit 30 is connected to the PID control unit 20, the first output end of the second comparison unit 40 is respectively connected to the first input end of the first comparison unit 30 and the PID control unit 20, and the second output end of the second comparison unit 40 is respectively connected to the second input end of the first comparison unit 30 and the PID control unit 20; the first switch unit 50 is connected to the second input end of the first comparison unit 30 and the PID control unit 20; 0 is respectively connected to the output end of the first comparison unit 30 and the second end of the TEC and is connected to the input voltage Vin; the second switch unit 60 is respectively connected to the first end of the TEC and the input end of the second comparison unit 40 and is connected to the input voltage Vin, the PID control unit 20 monitors the real-time temperature of the laser and the temperature when the laser outputs the preset wavelength through the monitoring unit to generate an error proportional voltage required for the laser to stably output the preset wavelength, and turns on and off the first switch unit 50 and the second switch unit 60 through the first comparison unit 30 and the second comparison unit 40, thereby changing the current direction and magnitude of the TEC to control the heating or cooling of the TEC, thereby achieving heating or cooling of the laser to stabilize to the preset temperature of the laser, thereby making the laser stably output the preset wavelength.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A laser wavelength control circuit, characterized in that: include: TEC, the TEC is connected to the laser and is used to heat or cool the laser to control the wavelength of the laser; A temperature monitoring unit, connected to the laser and used to monitor the real-time temperature of the laser; A PID control unit, connected to the temperature monitoring unit and used to control the current direction and current magnitude of the TEC; a first comparing unit, wherein a first input terminal of the first comparing unit is connected to the PID control unit; a second comparing unit, wherein a first output end of the second comparing unit is connected to the first input end of the first comparing unit and the PID control unit respectively, a second output end of the second comparing unit is connected to the second input end of the first comparing unit and the PID control unit respectively, and a second input end thereof is input with a TEC current; a first switch unit, the first switch unit being connected to the output terminal of the first comparison unit and the second terminal of the TEC respectively, and being connected to an input voltage Vin; a second switch unit, the second switch unit being connected to the first end of the TEC and the first input end of the second comparison unit respectively, and being connected to an input voltage Vin; The first comparison unit includes a comparator U7, and the second comparison unit includes a comparator U10; wherein the positive input terminal of the comparator U7 is connected to the PID control unit and the first output terminal of the comparator U10 respectively, and the negative input terminal is connected to the second output terminal of the comparator U10; the positive input terminal of the comparator U10 is connected to the second switching unit, and the negative input terminal inputs the TEC current; The circuit further includes a switch S1, a comparator U9, a switch S2, an amplifier U8, and a NOT gate; wherein the first end of the switch S1 is connected to the first output end of the comparator U10, the second end is connected to the power supply voltage VDD, and the third end is connected to the inverting input end of the amplifier U8; the non-inverting input end of the amplifier U8 inputs the TEC current, and the output end is respectively connected to the PID control unit and the first input end of the comparator U7; the first end of the switch S2 is connected to the second output end of the comparator U10, and the second end is respectively connected to the non-inverting input end of the comparator U9, the PID control unit, the output end of the amplifier U8, and the first input end of the comparator U7; the inverting input end of the comparator U9 is connected to the power supply voltage VCC, and the output end is connected to the first input end of the NOT gate; the second input end of the NOT gate is connected to the enable signal, and the output end is connected to the second input end of the comparator U7; The first output terminal of the comparator U10 generates a cooling signal, the first terminal of the switch S1 is connected to the third terminal, the first terminal of the switch S2 is disconnected from the second terminal, the output terminal of the comparator U7 is at a high level, the first switch unit is turned on, the second switch unit is turned off, the current on the TEC flows from the second terminal to the first terminal, and the TEC enters the cooling mode; The second output end of the comparator U10 generates a heating signal, the first end of the switch S1 is connected to the second end, the first end of the switch S2 is connected to the second end, the output end of the comparator U7 is at a low level, the first switch unit is not conducting, the second switch unit is conducting, the current on the TEC flows from the first end to the second end, and the TEC starts the heating mode.

2. The laser wavelength control circuit according to claim 1, characterized in that: The PID control unit includes a temperature voltage generating unit and an error proportional voltage generating unit; The temperature voltage generating unit is connected to the temperature monitoring unit and the error proportional voltage generating unit respectively, and the error proportional voltage generating unit is connected to the first input terminal of the first comparing unit.

3. The laser wavelength control circuit according to claim 2, characterized in that: The temperature voltage generating unit includes an amplifier U1 and a feedback resistor Rf; Among them, the positive input end of the amplifier U1 is connected to the temperature monitoring unit, and is connected to the reference voltage Vref, and is connected to the output end of the amplifier U1 through the feedback resistor Rf. The negative input end of the amplifier U1 is connected to half of the reference voltage Vref, and the output end of the amplifier U1 is connected to the error proportional voltage generating unit.

4. The laser wavelength control circuit according to claim 2, characterized in that: The error proportional voltage generating unit includes an amplifier U2 and a resistor R4; The positive input of the amplifier U2 is connected to the output of the amplifier U1 and to the output of the amplifier U2 through the resistor R4. The negative input of the amplifier U2 is connected to the target temperature voltage Vtemp of the laser. The output of the amplifier U2 is connected to the first input of the first comparison unit.

5. The laser wavelength control circuit according to claim 1, characterized in that: The first switch unit includes a MOS transistor Q1, and the second switch unit includes a MOS transistor Q2; The gate of the MOS transistor Q1 is connected to the output end of the first comparison unit, the source is connected to the second end of the TEC, and the drain is connected to the input voltage Vin; the gate of the MOS transistor Q2 is connected to the input end of the second comparison unit, the source is connected to the input voltage Vin, and the drain is connected to the first end of the TEC.

6. The laser wavelength control circuit according to claim 1, characterized in that: The circuit also includes amplifier U5 and amplifier U6; Among them, the non-inverting input end of the amplifier U5 is respectively connected to the PID control unit and the first input end of the first comparison unit, and is connected to the reference voltage Vref through the resistor R11. The reverse input end is connected to the output end of the amplifier U5 through the resistor R13 and the resistor R14 in sequence, and the output end of the amplifier U5 outputs the TEC voltage; the non-inverting input end of the amplifier U6 is respectively connected to the first input end of the second comparison unit and the second switch unit, and the reverse input end is respectively connected to the second input end of the second comparison unit and the output end of the amplifier U6 through the resistor R18, and the output end of the amplifier U6 outputs the TEC current.

7. The laser wavelength control circuit according to claim 1, characterized in that: The circuit also includes amplifier U3 and amplifier U4; Among them, the non-inverting input terminal of the amplifier U3 is connected to the PID control unit, the reverse input terminal is connected to the output terminal of the amplifier U3 through the resistor R8, and is connected to the reference voltage Vref through the resistor R9, the output terminal of the amplifier U3 is connected to the non-inverting input terminal of the amplifier U4 through the resistor R7; the reverse input terminal of the amplifier U4 is connected to the power supply voltage VDD, and the output terminal is connected to the first input terminal of the first comparison unit.

8. A laser, characterized in that: The invention comprises a laser body and a laser wavelength control circuit as claimed in any one of claims 1 to 7.

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