A single-frequency fiber laser driving system with low-noise multi-modulation interface

Abstract

The present invention provides a single-frequency fiber laser drive system with a low-noise, multi-modulation interface. The system includes a microcontroller module, a current modulation unit, a piezoelectric ceramic modulation unit, a temperature modulation unit, and a single-frequency fiber laser. The current modulation unit, the piezoelectric ceramic modulation unit, and the temperature modulation unit are each electrically connected to the microcontroller module at one end and to the single-frequency fiber laser at the other end. The current modulation unit includes a constant current drive module, a noise suppression module, a first signal source, and a current modulation module. The piezoelectric ceramic modulation unit includes a piezoelectric ceramic drive module, a piezoelectric ceramic module, a piezoelectric ceramic modulation module, and a second signal source. The temperature modulation unit includes a heating module, a temperature control module, a temperature modulation module, and a third signal source. The present invention implements the application of current modulation, PZT modulation, and temperature modulation multi-modulation interfaces for single-frequency fiber lasers, providing a multi-modulation interface for single-frequency fiber lasers. The system is simpler in design and inexpensive.

Description

Technical Field

[0001] The present invention relates to the field of laser driving technology, and in particular to a single-frequency fiber laser driving system with low noise and multiple modulation interfaces. Background Art

[0002] High-stability laser interferometers are a key component in gravitational wave detection, and frequency-stable lasers are one of the most important components. Achieving stable laser output from a single-frequency fiber laser requires three basic conditions: first, population inversion; second, the optical resonator cavity length; and third, the laser threshold condition.

[0003] Research is conducted on two aspects: the cavity length of the optical resonator and the laser threshold. Commonly used technologies include PZT modulation technology and current wavelength modulation technology. PZT modulation technology refers to the mechanical deformation of PZT under the action of an electric field. Based on this characteristic, it is glued to the internal doped fiber of the fiber laser. By applying different voltages to the PZT, the doped fiber inside the laser will be subjected to different tension or pressure, thereby changing the cavity length of its resonator or the period of the active phase-shifted fiber grating, thereby achieving modulation of the output frequency of the fiber laser. Current modulation technology refers to changing the output wavelength of the laser by changing the threshold current injected by the laser to achieve the purpose of wavelength tuning. For laser frequency stabilization, single PZT modulation and current modulation technology cannot achieve the purpose of frequency stabilization well, because the grating used in the single-frequency laser cavity and the overall cavity length are very sensitive to temperature. During the PZT modulation process, the temperature in the cavity will change drastically, which will affect the modulation frequency performance of the PZT. Aiming at the influence of cavity temperature, this paper proposes a temperature modulation technology to perform single longitudinal mode modulation on the laser resonant cavity temperature, and adds PZT modulation interface and current modulation interface. In order to achieve low noise processing, the circuit of this paper adds a noise suppression module to realize a single-frequency fiber laser with low noise and multiple modulation interfaces.

[0004] This low-noise multi-modulation interface approach effectively compensates for the effects of laser nonlinearity and temperature variations on frequency stability, providing highly precise light source stability. Semiconductor laser driver technology using a low-noise multi-modulation interface provides a crucial tool for gravitational wave detection. It improves the laser's frequency stability and controllability, enhancing system sensitivity and measurement accuracy. Summary of the Invention

[0005] In response to the technical problems existing in the above-mentioned background technology, the present invention proposes a single-frequency fiber laser driving system with low-noise multi-modulation interface. The system has a reasonable design and realizes the application of current modulation, PZT modulation, and temperature modulation multi-modulation interfaces for single-frequency fiber lasers. It can provide a multi-modulation interface for single-frequency fiber lasers, and has a simpler design and low cost.

[0006] To solve the above technical problems, the present invention provides a low-noise multi-modulation interface single-frequency fiber laser driving system, which includes a microcontroller module, a current modulation unit, a piezoelectric ceramic modulation unit, a temperature modulation unit and a single-frequency fiber laser; one end of the current modulation unit, the piezoelectric ceramic modulation unit and the temperature modulation unit are electrically connected to the microcontroller module, and the other end is electrically connected to the single-frequency fiber laser;

[0007] The current modulation unit includes a constant current drive module, a noise suppression module, a first signal source and a current modulation module; the constant current drive module is electrically connected to the microcontroller module, the current modulation module and the noise suppression module respectively, and the noise suppression module is electrically connected to the single-frequency fiber laser; the current modulation module is also electrically connected to the first signal source, and is used to tune the signal emitted by the first signal source and input it into the constant current drive module to generate a drive current to drive the single-frequency fiber laser to work; the constant current drive module receives the control signal output by the current modulation module, and outputs the modulated current to the noise suppression module, and then the noise suppression module achieves a low-noise output current through a noise suppression network to modulate the single-frequency fiber laser, so as to control the current output to the single-frequency fiber laser;

[0008] The piezoelectric ceramic modulation unit includes a piezoelectric ceramic driving module, a piezoelectric ceramic module, a piezoelectric ceramic modulation module and a second signal source; the signal input end of the piezoelectric ceramic modulation module is electrically connected to the second signal source, and the signal output end is electrically connected to the piezoelectric ceramic driving module; the piezoelectric ceramic driving module is also electrically connected to the microcontroller module and the piezoelectric ceramic module, respectively, and the piezoelectric ceramic module is electrically connected to the single-frequency fiber laser; the piezoelectric ceramic driving module receives the control signal output by the piezoelectric ceramic modulation module, controls the piezoelectric ceramic module to generate corresponding small displacement vibration to adjust the DBR resonant cavity of the single-frequency fiber laser, so as to achieve cavity length adjustment of the single-frequency fiber laser;

[0009] The temperature modulation unit includes a heating module, a temperature control module, a temperature modulation module and a third signal source; the signal input end of the temperature modulation module is electrically connected to the third signal source, and the signal output end is electrically connected to the heating module; and the heating module is also electrically connected to the temperature control module and the single-frequency fiber laser, respectively; the heating module receives a control signal output by the temperature modulation module; the temperature control module is used to control the heating module to modulate at a constant temperature, and is electrically connected to the microcontroller module and controlled by the microcontroller module; the heating module receives the control signal output by the temperature modulation module to perform temperature modulation on the single-frequency fiber laser;

[0010] The microcontroller module is used to set the driving current value of the constant current driving module, the temperature control working point of the temperature control module, and save the current working point as the working point set at startup.

[0011] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the circuit of the constant current driving module is composed of a low-noise power supply module, a light-emitting diode LD1, an N-MOS field-effect transistor Q1, a resistor R5, resistors R7 to R10, a capacitor C3, a second operational amplifier OPA2 and a third operational amplifier OPA3;

[0012] The low-noise power supply module is composed of a linear regulator LDO, a synchronous DC buck converter DCDC and an LC filter connected in sequence to output a clean and low-noise power supply;

[0013] The anode terminal of the light-emitting diode LD1 is electrically connected to the low-noise power supply module, and the cathode terminal is electrically connected to the drain terminal of the N-MOS field-effect transistor Q1; the gate terminal of the N-MOS field-effect transistor Q1 is electrically connected to the resistor R5 and is electrically connected to the output terminal of the third operational amplifier OPA3 through the resistor R5; the source terminal of the N-MOS field-effect transistor Q1 is electrically connected to the resistor R10 and is grounded through the resistor R10; the non-inverting input terminal of the third operational amplifier OPA3 is electrically connected to the current modulation module; one end of the resistor R8 is electrically connected to the source terminal of the N-MOS field-effect transistor Q1, and the other end is electrically connected to the non-inverting input terminal of the second operational amplifier OPA2; one end of the resistor R7 is electrically connected to the inverting input terminal of the second operational amplifier OPA2, and the other end is electrically connected to the output terminal of the second operational amplifier OPA2; one end of the resistor R9 is grounded, and the other end is electrically connected to the inverting input terminal of the second operational amplifier OPA2; one end of the capacitor C3 is electrically connected to the output terminal of the second operational amplifier OPA2, and the other end is electrically connected to the connection point between the resistor R7 and the resistor R9.

[0014] The low-noise multi-modulation interface single-frequency fiber laser driving system, wherein: the low-noise power supply module can adopt a linear regulator or a synchronous DC buck converter plus an inductor-capacitor low-pass filter to achieve the purpose of low noise.

[0015] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the circuit of the noise suppression module is composed of a resistor R6, a resistor R11 and a capacitor C4; one end of the resistor R6 is electrically connected to the output end of the second operational amplifier OPA2, and the other end is electrically connected to the inverting input end of the third operational amplifier OPA3; one end of the resistor R11 is electrically connected to the inverting input end of the third operational amplifier OPA3, and the other end is electrically connected to the capacitor C4 and connected to the output end of the third operational amplifier OPA3 through the capacitor C4.

[0016] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the current modulation module is composed of resistors R1 to R4, a capacitor C1 and a first operational amplifier OPA1; one end of the resistor R1 is electrically connected to the microcontroller module, and the other end is electrically connected to the non-inverting input of the first operational amplifier OPA1; one end of the resistor R2 is electrically connected to the first signal source, and the other end is also electrically connected to the non-inverting input of the first operational amplifier OPA1; one end of the resistor R3 is electrically connected to the output of the first operational amplifier OPA1, and the other end is electrically connected to the resistor R4 and grounded through the resistor R4; the inverting input of the first operational amplifier OPA1 is electrically connected to the connection point between the resistor R3 and the resistor R4; one end of the capacitor C1 is electrically connected to the output of the first operational amplifier OPA1, and the other end is electrically connected to the connection point between the resistor R3 and the resistor R4; the output of the first operational amplifier OPA1 is connected to the non-inverting input of the third operational amplifier OPA3.

[0017] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the piezoelectric ceramic modulation module is composed of resistors R11 to R15, a fourth operational amplifier OPA4, and a fifth operational amplifier OPA5; one end of the resistor R11 is electrically connected to the microcontroller module, and the other end is electrically connected to the non-inverting input end of the fourth operational amplifier OPA4; one end of the resistor R12 is electrically connected to the second signal source, and the other end is electrically connected to the non-inverting input end of the fourth operational amplifier OPA4; one end of the resistor R13 is electrically connected to the inverting input end of the fourth operational amplifier OPA4. The resistor R14 has one end electrically connected to the output of the fourth operational amplifier OPA4, and the other end electrically connected to the inverting input of the fifth operational amplifier OPA5; the resistor R15 has one end electrically connected to the inverting input of the fifth operational amplifier OPA5, and the other end electrically connected to the output of the fifth operational amplifier OPA5; the non-inverting input of the fifth operational amplifier OPA5 is connected to the power supply VCC, and the output of the piezoelectric ceramic is output. The modulation signal of the piezoelectric ceramic is electrically connected to the piezoelectric ceramic driving module.

[0018] The single-frequency fiber laser driving system with low noise and multi-modulation interface, wherein: the piezoelectric ceramic driving module is composed of resistors R16 to R20, a sixth operational amplifier OPA6, a capacitor C5, an NPN transistor Q2, a PNP transistor Q3 and a high-voltage module;

[0019] One end of the resistor R16 is electrically connected to the output end of the fifth operational amplifier OPA5, and the other end is electrically connected to the inverting input end of the sixth operational amplifier OPA6; the non-inverting input end of the sixth operational amplifier OPA6 is connected to the power supply VCC; one end of the resistor R17 is electrically connected to the inverting input end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module; the capacitor C5 is connected in parallel to both ends of the resistor R17; one end of the resistor R20 is electrically connected to the output end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module; the collector of the NPN transistor Q2 is electrically connected to the high-voltage module, the base is electrically connected to the base of the PNP transistor Q3, and the emitter is connected in series with the resistor R18 and the resistor R19 in sequence and then connected to the emitter of the PNP transistor Q3; the collector of the PNP transistor Q3 is grounded.

[0020] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the temperature modulation module includes a linear voltage source; one end of the linear voltage source is electrically connected to the third signal source, and the other end is electrically connected to one end of the LC filter; the other end of the LC filter is electrically connected to the heating module;

[0021] The voltage of the linear voltage source is proportionally amplified with the signal source; the linear voltage source is connected to the LC filter to output a control signal to the heating module; after the heating module receives the control signal filtered by the LC filter, it controls the temperature to rise at a certain frequency.

[0022] The single-frequency fiber laser drive system with a low-noise multi-modulation interface, wherein: the temperature control module includes a temperature comparison amplifier, a compensation network, a PWM driver, an H-bridge and a TEC module; the TEC module includes a thermoelectric cooler and a thermistor NTC; one end of the temperature comparison amplifier is electrically connected to the microcontroller module, and the other end is electrically connected to the PWM driver through the compensation network; the signal output end of the PWM driver is electrically connected to the H-bridge; the H-bridge is electrically connected to the TEC module; the actual temperature value is converted into a voltage signal by the thermistor NTC, the voltage signal is input to the temperature comparison amplifier for amplification and compared with the voltage value corresponding to the set target temperature to generate an error signal, the output error signal voltage value is output to the PWM driver through the compensation network to drive the H-bridge, the H-bridge controls the heating or cooling of the TEC module, and the thermistor NTC samples the temperature of the TEC module and feeds it back to the temperature comparison amplifier to form a closed-loop control.

[0023] The single-frequency fiber laser driving system with a low-noise multi-modulation interface, wherein: the microcontroller module is composed of an STM32 single-chip microcomputer and a host computer PC electrically connected to the STM32 single-chip microcomputer, a digital-to-analog converter, an IO port, an analog-to-digital converter, a power supply and FLASH data storage.

[0024] By adopting the above technical solution, the present invention has the following beneficial effects:

[0025] The low-noise, multi-modulation interface single-frequency fiber laser drive system of the present invention is rationally conceived. Based on the design concept of a single-frequency fiber laser drive circuit with a PZT single modulation interface, the temperature variables of the single-frequency fiber laser resonant cavity are considered, and temperature modulation interfaces and current modulation interfaces are added. This system not only considers the way in which the piezoelectric ceramic drives the resonant cavity to deform and thus change the cavity length, but also considers the influence of the resonant cavity temperature on frequency stabilization. The use of a temperature modulation interface is an innovative idea because temperature affects the cavity length of the resonant cavity, which is crucial to the single longitudinal mode output of the laser in terms of single frequency. Changes in the cavity length affect the modulation range of the single longitudinal mode, that is, temperature modulation can promote frequency stabilization from the perspective of the resonant cavity temperature. Furthermore, the addition of a current modulation interface makes the present invention possess more functions than a single modulation interface single-frequency fiber laser drive circuit, and has lower single-board noise. Compared with a drive circuit with multiple single modulation interfaces, the present invention has greater practicality and higher integration, and can realize multi-modulation functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. 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.

[0027] Figure 1 This is a structural principle diagram of the single-frequency fiber laser driving system with a low-noise multi-modulation interface of the present invention;

[0028] Figure 2 This is a circuit diagram of a current modulation module involved in the single-frequency fiber laser driving system with a low-noise multi-modulation interface of the present invention;

[0029] Figure 3 This is a circuit diagram of a constant current drive module and a noise suppression module involved in the single-frequency fiber laser drive system with a low-noise multi-modulation interface of the present invention;

[0030] Figure 4 This is a circuit diagram of a piezoelectric ceramic modulation module involved in the single-frequency fiber laser driving system with low-noise multi-modulation interface of the present invention;

[0031] Figure 5 This is a circuit diagram of a piezoelectric ceramic drive module involved in the single-frequency fiber laser drive system with a low-noise multi-modulation interface of the present invention;

[0032] Figure 6 This is a structural schematic diagram of the temperature modulation module involved in the single-frequency fiber laser driving system with low-noise multi-modulation interface of the present invention;

[0033] Figure 7 This is a structural schematic diagram of the temperature control module involved in the single-frequency fiber laser driving system with low-noise multi-modulation interface of the present invention;

[0034] Figure 8 This is a structural schematic diagram of a low-noise power supply module involved in the single-frequency fiber laser driving system with a low-noise multi-modulation interface of the present invention;

[0035] Figure 9 This is a structural schematic diagram of the microcontroller module involved in the single-frequency fiber laser driving system with low noise and multi-modulation interface of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. 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] The present invention will be further explained below with reference to specific embodiments.

[0038] like Figure 1 As shown, this embodiment provides a low-noise multi-modulation interface single-frequency fiber laser driving system, including a microcontroller module 1, a constant current driving module 2, a noise suppression module 3, a piezoelectric ceramic driving module 4, a piezoelectric ceramic module 5, a heating module 6, a temperature control module 7, a single-frequency fiber laser 8, a current modulation module 9, a piezoelectric ceramic modulation module 10 and a temperature modulation module 11.

[0039] The microcontroller module 1 is electrically connected to the constant current drive module 2, the piezoelectric ceramic drive module 4, and the temperature control module 7, respectively, and is used to set the drive current value of the constant current drive module 2, the temperature control working point of the temperature control module 7, and save the current working point as the working point set for power on.

[0040] like Figure 9 As shown, the microcontroller module 1 consists of an STM32 microcontroller, a host computer connected to the STM32 microcontroller, a digital-to-analog converter (i.e., a DAC module), an I / O port, an analog-to-digital converter (i.e., an ADC module), a power supply, and a FLASH data storage module. The STM32 microcontroller is a 32-bit memory microcontroller based on the ARM Cortex-M core. Produced by ST (STMicroelectronics), it features high performance, low power consumption, a rich peripheral set, and ease of development. The STM32 microcontroller's power supply is typically a 3.3V DC power supply. The STM32 microcontroller has a variety of communication interfaces, enabling data exchange with other devices. The STM32 microcontroller connects and communicates with the ADC module (analog-to-digital converter) and DAC module (digital-to-analog converter) via these communication interfaces. Furthermore, the STM32 microcontroller integrates a wealth of peripherals, such as I / O ports, through which the STM32 microcontroller can output signals and communicate data with the host computer, enabling data exchange with the host computer.

[0041] The constant current drive module 2, the noise suppression module 3, the first signal source, and the current modulation module 9 together constitute the current modulation unit of the single-frequency fiber laser 8. The constant current drive module 2 is also electrically connected to the current modulation module 9 and the noise suppression module 3, respectively, and the noise suppression module 3 is electrically connected to the single-frequency fiber laser 8. The constant current drive module 2 receives the control signal output by the current modulation module 9 and outputs a modulated current to the noise suppression module 3. The noise suppression module 3 then modulates the single-frequency fiber laser 8 to achieve a low-noise output current through the noise suppression network, thereby controlling the current output to the single-frequency fiber laser 8.

[0042] like Figure 3 As shown, the circuit of the constant current drive module 2 consists of a low-noise power supply module, a light-emitting diode LD1, an N-MOS field-effect transistor Q1, a resistor R5, resistors R7 to R10, a capacitor C3, a second operational amplifier OPA2, and a third operational amplifier OPA3. The anode end of the light-emitting diode LD1 is electrically connected to the low-noise power supply module, and the cathode end is electrically connected to the drain of the N-MOS field-effect transistor Q1; the gate of the N-MOS field-effect transistor Q1 is electrically connected to the resistor R5 and is electrically connected to the output end of the third operational amplifier OPA3 through the resistor R5, and the source of the N-MOS field-effect transistor Q1 is electrically connected to the resistor R10 and is grounded through the resistor R10; the resistor R5 can prevent the output of the N-MOS field-effect transistor Q1 from oscillating and increase stability; the non-inverting input end of the third operational amplifier OPA3 is electrically connected to the current modulation module Block 9; one end of the resistor R8 is electrically connected to the source of the N-MOS field effect transistor Q1, and the other end is electrically connected to the non-inverting input of the second operational amplifier OPA2; one end of the resistor R7 is electrically connected to the inverting input of the second operational amplifier OPA2, and the other end is electrically connected to the output of the second operational amplifier OPA2; one end of the resistor R9 is grounded, and the other end is electrically connected to the inverting input of the second operational amplifier OPA2; one end of the capacitor C3 is electrically connected to the output of the second operational amplifier OPA2, and the other end is electrically connected to the junction of the resistor R7 and the resistor R9. Figure 8 In order to achieve the purpose of low noise, the low-noise power supply module can be composed of a linear regulator LDO, a synchronous DC buck converter DCDC and an LC filter to obtain a clean and low-noise output power supply; when the voltage across the single-frequency fiber laser 8 does not meet its own voltage drop, the output voltage of the low-noise power supply module can be adjusted so that the voltage applied to the single-frequency fiber laser 8 is greater than its own voltage drop; if it is much greater than the single-frequency fiber laser 8's own voltage drop, the excess voltage will act on the N-MOS field-effect transistor Q1, so it needs to be heat-dissipated.

[0043] like Figure 3As shown, the circuit of the noise suppression module 3 is composed of a resistor R6, a resistor R11 and a capacitor C4; wherein, one end of the resistor R6 is electrically connected to the output end of the second operational amplifier OPA2 of the constant current driving module 2, and the other end is electrically connected to the inverting input end of the third operational amplifier OPA3 of the constant current driving module 2; one end of the resistor R11 is electrically connected to the inverting input end of the third operational amplifier OPA3, and the other end is electrically connected to the capacitor C4 and connected to the output end of the third operational amplifier OPA3 through the capacitor C4.

[0044] The current modulation module 9 is also connected to the first signal source, and is used to tune the signal sent by the first signal source and input it into the constant current driving module 2 to generate a driving current to drive the single-frequency fiber laser 8 to work.

[0045] like Figure 2 As shown, the current modulation module 9 is composed of resistors R1 to R4, a capacitor C1, and a first operational amplifier OPA1. One end of resistor R1 is electrically connected to the DAC module of the microcontroller module 1, and the other end is electrically connected to the non-inverting input of the first operational amplifier OPA1. One end of resistor R2 is electrically connected to the first signal source, and the other end is also electrically connected to the non-inverting input of the first operational amplifier OPA1. One end of resistor R3 is electrically connected to the output of the first operational amplifier OPA1, and the other end is electrically connected to resistor R4 and grounded through resistor R4. The inverting input of the first operational amplifier OPA1 is electrically connected to the connection point between resistors R3 and R4. One end of capacitor C1 is connected to the output of the first operational amplifier OPA1, and the other end is electrically connected to the connection point between resistors R3 and R4. Capacitor C1 serves as a feedback capacitor to improve the output stability of the first operational amplifier OPA1. At the same time, the output of the first operational amplifier OPA1 is connected to the non-inverting input of the third operational amplifier OPA3 of the constant current driver module 2.

[0046] The piezoelectric ceramic drive module 4, the piezoelectric ceramic module 5, the piezoelectric ceramic modulation module 10, and the second signal source together constitute a piezoelectric ceramic modulation unit for modulating the cavity length of the single-frequency fiber laser 8. The signal input end of the piezoelectric ceramic modulation module 10 is electrically connected to the second signal source, and the signal output end is electrically connected to the piezoelectric ceramic drive module 4. The piezoelectric ceramic drive module 4 is electrically connected to the piezoelectric ceramic module 5, which is electrically connected to the single-frequency fiber laser 8. The piezoelectric ceramic drive module 4 receives the control signal output by the piezoelectric ceramic modulation module 10 and controls the piezoelectric ceramic module 5 to generate a corresponding small displacement vibration to adjust the DBR resonant cavity of the single-frequency fiber laser 8, thereby achieving cavity length adjustment of the single-frequency fiber laser 8.

[0047] like Figure 4As shown, the piezoelectric ceramic modulation module 10 is composed of resistors R11 to R15, a fourth operational amplifier OPA4, and a fifth operational amplifier OPA5. Among them, one end of the resistor R11 is electrically connected to the DAC module of the microcontroller module 1, and the other end is electrically connected to the non-inverting input terminal of the fourth operational amplifier OPA4; one end of the resistor R12 is electrically connected to the second signal source, and the other end is electrically connected to the non-inverting input terminal of the fourth operational amplifier OPA4; one end of the resistor R13 is electrically connected to the inverting input terminal of the fourth operational amplifier OPA4, and the other end is electrically connected to the output terminal of the fourth operational amplifier OPA4; one end of the resistor R14 is electrically connected to the output terminal of the fourth operational amplifier OPA4, and the other end is electrically connected to the inverting input terminal of the fifth operational amplifier OPA5; one end of the resistor R15 is electrically connected to the inverting input terminal of the fifth operational amplifier OPA5, and the other end is electrically connected to the output terminal of the fifth operational amplifier OPA5; the non-inverting input terminal of the fifth operational amplifier OPA5 is connected to the power supply VCC, and the output terminal outputs the modulation signal of the piezoelectric ceramic (PZT) and is electrically connected to the piezoelectric ceramic drive module 4.

[0048] like Figure 5 As shown, the piezoelectric ceramic driving module 4 is composed of resistors R16 to R20, a sixth operational amplifier OPA6, a capacitor C5, an NPN transistor Q2, a PNP transistor Q3 and a high-voltage module. Among them, one end of the resistor R16 is connected to the output end of the fifth operational amplifier OPA5 of the piezoelectric ceramic modulation module 10, and the other end is electrically connected to the inverting input end of the sixth operational amplifier OPA6; the non-inverting input end of the sixth operational amplifier OPA6 is connected to the power supply VCC; one end of the resistor R17 is electrically connected to the inverting input end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module 5; the capacitor C5 is connected in parallel to both ends of the resistor R17, which serves as a compensation capacitor to compensate for the loop stability; one end of the resistor R20 is electrically connected to the output end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module 5; the collector of the NPN transistor Q2 is electrically connected to the high-voltage module, the base is electrically connected to the base of the PNP transistor Q3, and the emitter is connected in series with resistors R18 and R19 in sequence and then connected to the emitter of the PNP transistor Q3; the collector of the PNP transistor Q3 is grounded.

[0049] The signal input end of the temperature modulation module 11 is electrically connected to the third signal source, and the signal output end is electrically connected to the heating module 6. The heating module 6 is also electrically connected to the temperature control module 7 and the single-frequency fiber laser 8. The heating module 6 receives the control signal output by the temperature modulation module 11. The temperature control module 7 is controlled by the microcontroller module 1 and controls the heating module 6 to modulate at a constant temperature. The heating module 6 receives the control signal output by the temperature modulation module 11 to perform temperature modulation on the single-frequency fiber laser 8.

[0050] like Figure 6 As shown, the temperature modulation module 11 includes a linear voltage source; one end of the linear voltage source is electrically connected to a third signal source, and the other end is electrically connected to one end of the LC filter of the low-noise power module; the other end of the LC filter of the low-noise power module is electrically connected to the heating module 6. The voltage of the linear voltage source is proportionally amplified with the signal source; one end of the linear voltage source is electrically connected to the third signal source, and the other end is connected to the LC filter of the low-noise power module to output a control signal to the heating module 6. The heating module 6 receives the control signal after filtering by the LC filter of the low-noise power module. There is a certain linear relationship between the control signal after filtering by the LC filter of the low-noise power module and the heating module 6, and the temperature is controlled to rise at a certain frequency.

[0051] like Figure 7 As shown, the temperature control module 7 includes a temperature comparator amplifier, a compensation network, a PWM driver, an H-bridge, and a TEC module. The TEC module includes a thermoelectric cooler (i.e., a TEC cooling plate) and a thermistor (NTC). One end of the temperature comparator amplifier is electrically connected to the ADC module of the microcontroller module 1, and the other end is electrically connected to the PWM driver via the compensation network. The signal output end of the PWM driver is electrically connected to the H-bridge, which is electrically connected to the TEC module. The actual temperature value is converted into a voltage signal by the thermistor (NTC). The voltage signal is input into the temperature comparator amplifier (differential amplifier) ​​for amplification and compared with the voltage value corresponding to the set target temperature to generate an error signal. The output error signal voltage value passes through a compensation network, such as a PID or self-tuning PID algorithm, and is output to the PWM driver to drive the H-bridge. The H-bridge controls the heating or cooling of the TEC module. The thermistor (NTC) samples the temperature of the TEC module and feeds it back to the temperature comparator amplifier to form a closed-loop control.

[0052] The low-noise multi-modulation interface single-frequency fiber laser driving system of the present invention mainly realizes the current, cavity length and temperature modulation of the single-frequency fiber laser 8 through a microcontroller module 1 and a current modulation unit, a piezoelectric ceramic modulation unit and a temperature modulation unit.

[0053] Among them, the current modulation interface of the current modulation drive circuit outputs a signal to the constant current drive module 2 through the first signal source. The current output by the constant current drive module 2 and the voltage output by the microcontroller module 1 are in a certain linear relationship. The constant current drive module 2 outputs current to drive the single-frequency fiber laser 8, but the light emitted by it is related to the magnitude of the current passing through, and the smaller the current ripple passing through, the smaller the output noise.

[0054] Therefore, in order to achieve the purpose of low noise, the processing can be carried out from two parts: the low-noise power supply module and the constant current drive module 2. The low-noise power supply module itself provides current to the single-frequency fiber laser 8. The noise of the low-noise power supply module itself will affect the quality of the output light. In order to achieve the purpose of low noise, the linear regulator LDO of the low-noise power supply module can effectively suppress low-frequency noise, and then the bypass capacitor, that is, the capacitor C1 of the current modulation module 9, can filter out high-frequency noise. In this way, a clean and low-noise low-noise power supply module can be obtained. The constant current drive module 2 adds a noise suppression module 3, and the noise suppression module 3 provides a pair of zero poles for the constant current drive module 2. This pair of zero poles improves the stability of the entire constant current driving module 2 and enhances the noise attenuation capability.

[0055] Microcontroller module 1 outputs control voltage v ctrl1 and the first signal source v signal1 is coupled to the non-inverting input of the third operational amplifier OPA3, as Figure 2 Where R1=R2, R3=R4, then according to the adder principle, we can get v out =v ctrl1 +v signal1 ,v out As Figure 3 The input of the constant current drive module 2, due to the "virtual short and virtual break" characteristics of the second operational amplifier OPA2, can be obtained From this, we can get the current I flowing through the single-frequency fiber laser 8 LD and control voltage signal v out The relationship between them.

[0056] The PZT modulation interface is composed of Figure 4 The second signal source outputs a signal to the piezoelectric ceramic modulation module 10, and its fourth operational amplifier OPA4 acts as a voltage follower, and its output voltage v op4 =(v ctrl2 +v signal2 ),v ctrl2 As a DAC module of the microcontroller module 1 (such as Figure 9 ) output control voltage signal, v signal2 It is the control signal output by the second signal source.

[0057] Then the PZT modulation signal v is obtained through the fifth operational amplifier OPA5 pzt Output to Figure 5 In the circuit of the piezoelectric ceramic driving module 4, the non-inverting input terminal of the fifth operational amplifier OPA5 is connected to the power supply VCC. The output piezoelectric ceramic modulation signal is given to Figure 5The circuit of the piezoelectric ceramic driving module 4.

[0058] Figure 5 The A and B complementary symmetrical circuit composed of the NPN transistor Q2 and the PNP transistor Q3 plays the role of current expansion. It should be noted that the current expansion is related to the output capacity of the sixth operational amplifier OPA6. If the output current requirement is too large, the output distortion will be caused due to the insufficient load capacity of the sixth operational amplifier OPA6.

[0059] The output of the sixth operational amplifier OPA6 It is worth noting that as a high-power output power amplifier, the sixth operational amplifier OPA6 must pay attention to its heat dissipation. Moreover, since the amplification gain is determined by the resistors R17 and R16, it is necessary to pay attention to the problem of insufficient bandwidth of the sixth operational amplifier OPA6 caused by excessive gain.

[0060] The sixth operational amplifier OPA6 outputs v op6 By expanding the current, a control signal with sufficient power is obtained to drive the Figure 5 The piezoelectric ceramic module 5 in the embodiment achieves the effect of piezoelectric ceramic modulation and the effect of PZT modulation.

[0061] like Figure 6 As shown, the temperature modulation interface is connected by a third signal source, wherein the third signal source drives the linear voltage source to output voltage, and the control signal of the third signal source and the output voltage of the linear voltage source are in a certain proportional relationship. Then, the output voltage noise is suppressed by the LC filter network of the low-noise power supply module. The linear voltage source can be a common topology of buck, boost, and buck-boost.

[0062] The above-mentioned heating module 6 is generally a voltage-driven module, and its temperature rise is proportional to the input control voltage signal. However, it is worth noting that the frequency of the input control signal cannot be too high, and the general period is at the millisecond level.

[0063] like Figure 7 As shown, the thermistor NTC of the temperature control module 7 is tightly attached to the edge of the thermoelectric cooler, that is, the TEC cooling piece, to feedback the real-time temperature. The temperature control module 7 can be selected according to the output power. The temperature control module 7 with low output power can use the integrated chip MAX1978 or MAX1968 series chip for temperature control setting, which has a small size and high integration. If the output power is large, it needs to be based on Figure 1 The structure diagram is used to build a circuit to achieve temperature control effect.

[0064] The temperature control module 7 is mainly used to ensure that the heating module 6 is in a constant temperature environment and is not disturbed by the external environment.

[0065] The heating module 6 is in close contact with the single-frequency fiber laser 8, and the temperature of the single-frequency fiber laser 8 is controlled by changing the temperature of the heating module 6, causing the optical resonant cavity inside the single-frequency fiber laser 8 (the single-frequency fiber laser 8 is mainly composed of a gain medium, an optical resonant cavity and a pump source) to expand and contract due to heat, thereby achieving the effect of changing the cavity length, and finally realizing temperature modulation of the single-frequency fiber laser 8.

[0066] The present invention realizes the application of current modulation, piezoelectric ceramic modulation and temperature modulation multi-modulation interfaces for single-frequency fiber lasers, can provide multi-modulation interfaces for single-frequency fiber lasers, has a simpler design and is low in cost.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-noise, multi-modulation interface, single-frequency fiber laser drive system, characterized by: The system comprises a microcontroller module (1), a current modulation unit, a piezoelectric ceramic modulation unit, a temperature modulation unit and a single-frequency fiber laser (8); one end of each of the current modulation unit, the piezoelectric ceramic modulation unit and the temperature modulation unit is electrically connected to the microcontroller module (1) and the other end is electrically connected to the single-frequency fiber laser (8); The current modulation unit comprises a constant current driving module (2), a noise suppression module (3), a first signal source and a current modulation module (9); the constant current driving module (2) is electrically connected to the microcontroller module (1), the current modulation module (9) and the noise suppression module (3) respectively, and the noise suppression module (3) is electrically connected to the single-frequency fiber laser (8); the current modulation module (9) is also electrically connected to the first signal source, and is used to tune the signal emitted by the first signal source and input it into the constant current driving module (2) to generate a driving current to drive the single-frequency fiber laser (8) to work; the constant current driving module (2) receives the control signal output by the current modulation module (9), and outputs a modulated current to the noise suppression module (3), and then the noise suppression module (3) achieves a low-noise output current through a noise suppression network to modulate the single-frequency fiber laser (8), so as to control the current output to the single-frequency fiber laser (8); The piezoelectric ceramic modulation unit comprises a piezoelectric ceramic drive module (4), a piezoelectric ceramic module (5), a piezoelectric ceramic modulation module (10) and a second signal source; the signal input end of the piezoelectric ceramic modulation module (10) is electrically connected to the second signal source, and the signal output end is electrically connected to the piezoelectric ceramic drive module (4); the piezoelectric ceramic drive module (4) is also electrically connected to the microcontroller module (1) and the piezoelectric ceramic module (5), respectively, and the piezoelectric ceramic module (5) is electrically connected to the single-frequency fiber laser (8); the piezoelectric ceramic drive module (4) receives the control signal output by the piezoelectric ceramic modulation module (10), and controls the piezoelectric ceramic module (5) to generate corresponding micro-displacement vibration to adjust the DBR resonant cavity of the single-frequency fiber laser (8), so as to achieve cavity length adjustment of the single-frequency fiber laser (8); The temperature modulation unit comprises a heating module (6), a temperature control module (7), a temperature modulation module (11) and a third signal source; the signal input end of the temperature modulation module (11) is electrically connected to the third signal source, and the signal output end is electrically connected to the heating module (6); and the heating module (6) is also electrically connected to the temperature control module (7) and the single-frequency fiber laser (8) respectively; the heating module (6) receives the control signal output by the temperature modulation module (11); the temperature control module (7) is used to control the heating module (6) to modulate at a constant temperature, and is electrically connected to the microcontroller module (1) and controlled by the microcontroller module (1); the heating module (6) receives the control signal output by the temperature modulation module (11) to perform temperature modulation on the single-frequency fiber laser (8); The microcontroller module (1) is used to set the driving current value of the constant current driving module (2), the temperature control working point of the temperature control module (7), and to save the current working point as the working point set at startup.

2. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 1, characterized in that: The circuit of the constant current driving module (2) is composed of a low-noise power supply module, a light-emitting diode LD1, an N-MOS field-effect transistor Q1, a resistor R5, resistors R7 to R10, a capacitor C3, a second operational amplifier OPA2, and a third operational amplifier OPA3; The low-noise power supply module is composed of a linear regulator LDO, a synchronous DC buck converter DCDC and an LC filter connected in sequence to output a clean and low-noise power supply; The anode end of the light-emitting diode LD1 is electrically connected to the low-noise power supply module, and the cathode end is electrically connected to the drain of the N-MOS field effect transistor Q1; the gate of the N-MOS field effect transistor Q1 is electrically connected to the resistor R5 and electrically connected to the output end of the third operational amplifier OPA3 through the resistor R5, and the source of the N-MOS field effect transistor Q1 is electrically connected to the resistor R10 and grounded through the resistor R10; the non-inverting input end of the third operational amplifier OPA3 is electrically connected to the current modulation module (9); one end of the resistor R8 is electrically connected to the source of the N-MOS field effect transistor Q1, and the other end is electrically connected to the non-inverting input end of the second operational amplifier OPA2; one end of the resistor R7 is electrically connected to the inverting input end of the second operational amplifier OPA2, and the other end is electrically connected to the output end of the second operational amplifier OPA2; one end of the resistor R9 is grounded, and the other end is electrically connected to the inverting input end of the second operational amplifier OPA2; one end of the capacitor C3 is electrically connected to the output end of the second operational amplifier OPA2, and the other end is electrically connected to the connection point between the resistor R7 and the resistor R9.

3. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 2, characterized in that: In order to achieve the purpose of low noise, the low-noise power supply module can adopt a linear regulator or a synchronous DC buck converter plus an inductor-capacitor low-pass filter.

4. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 2, wherein: The circuit of the noise suppression module (3) is composed of a resistor R6, a resistor R11 and a capacitor C4; one end of the resistor R6 is electrically connected to the output end of the second operational amplifier OPA2, and the other end is electrically connected to the inverting input end of the third operational amplifier OPA3; one end of the resistor R11 is electrically connected to the inverting input end of the third operational amplifier OPA3, and the other end is electrically connected to the capacitor C4 and connected to the output end of the third operational amplifier OPA3 through the capacitor C4.

5. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 2, characterized in that: The current modulation module (9) is composed of resistors R1 to R4, a capacitor C1 and a first operational amplifier OPA1; one end of the resistor R1 is electrically connected to the microcontroller module (1), and the other end is electrically connected to the non-inverting input end of the first operational amplifier OPA1; one end of the resistor R2 is electrically connected to the first signal source, and the other end is also electrically connected to the non-inverting input end of the first operational amplifier OPA1; one end of the resistor R3 is electrically connected to the output end of the first operational amplifier OPA1, and the other end is electrically connected to the resistor R4 and grounded through the resistor R4; the inverting input end of the first operational amplifier OPA1 is electrically connected to the connection point between the resistor R3 and the resistor R4; one end of the capacitor C1 is electrically connected to the output end of the first operational amplifier OPA1, and the other end is electrically connected to the connection point between the resistor R3 and the resistor R4; the output end of the first operational amplifier OPA1 is connected to the non-inverting input end of the third operational amplifier OPA3.

6. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 1, characterized in that: The piezoelectric ceramic modulation module (10) is composed of resistors R11 to R15, a fourth operational amplifier OPA4, and a fifth operational amplifier OPA5; One end of the resistor R11 is electrically connected to the microcontroller module (1), and the other end is electrically connected to the non-inverting input of the fourth operational amplifier OPA4; one end of the resistor R12 is electrically connected to the second signal source, and the other end is electrically connected to the non-inverting input of the fourth operational amplifier OPA4; one end of the resistor R13 is electrically connected to the inverting input of the fourth operational amplifier OPA4, and the other end is electrically connected to the output of the fourth operational amplifier OPA4; one end of the resistor R14 is electrically connected to the output of the fourth operational amplifier OPA4, and the other end is electrically connected to the inverting input of the fifth operational amplifier OPA5; one end of the resistor R15 is electrically connected to the inverting input of the fifth operational amplifier OPA5, and the other end is electrically connected to the output of the fifth operational amplifier OPA5; the non-inverting input of the fifth operational amplifier OPA5 is connected to the power supply VCC, and the output outputs the modulation signal of the piezoelectric ceramic and is electrically connected to the piezoelectric ceramic drive module (4).

7. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 6, characterized in that: The piezoelectric ceramic driving module (4) is composed of resistors R16 to R20, a sixth operational amplifier OPA6, a capacitor C5, an NPN transistor Q2, a PNP transistor Q3 and a high-voltage module; One end of the resistor R16 is electrically connected to the output end of the fifth operational amplifier OPA5, and the other end is electrically connected to the inverting input end of the sixth operational amplifier OPA6; the non-inverting input end of the sixth operational amplifier OPA6 is connected to the power supply VCC; one end of the resistor R17 is electrically connected to the inverting input end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module (5); the capacitor C5 is connected in parallel to both ends of the resistor R17; one end of the resistor R20 is electrically connected to the output end of the sixth operational amplifier OPA6, and the other end is electrically connected to the piezoelectric ceramic module (5); the collector of the NPN transistor Q2 is electrically connected to the high-voltage module, the base is electrically connected to the base of the PNP transistor Q3, and the emitter is connected in series with the resistor R18 and the resistor R19 in sequence and then connected to the emitter of the PNP transistor Q3; the collector of the PNP transistor Q3 is grounded.

8. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 2, characterized in that: The temperature modulation module (11) comprises a linear voltage source; one end of the linear voltage source is electrically connected to the third signal source, and the other end is electrically connected to one end of the LC filter; the other end of the LC filter is electrically connected to the heating module (6); The voltage of the linear voltage source is proportionally amplified with respect to the signal source; the linear voltage source is connected to the LC filter to output a control signal to the heating module (6); after the heating module (6) receives the control signal filtered by the LC filter, it controls the temperature to rise at a certain frequency.

9. The low-noise, multi-modulation interface, single-frequency fiber laser drive system according to claim 1, characterized in that: The temperature control module (7) includes a temperature comparison amplifier, a compensation network, a PWM driver, an H-bridge and a TEC module; the TEC module includes a thermoelectric cooler and a thermistor NTC; one end of the temperature comparison amplifier is electrically connected to the microcontroller module (1), and the other end is electrically connected to the PWM driver through the compensation network; The signal output terminal of the PWM driver is electrically connected to the H-bridge; The H-bridge is electrically connected to the TEC module; the actual temperature value is converted into a voltage signal by a thermistor NTC. The voltage signal is input into a temperature comparator amplifier for amplification and compared with the voltage value corresponding to a set target temperature to generate an error signal. The output error signal voltage value is output to the PWM driver through the compensation network to drive the H-bridge. The H-bridge controls the heating or cooling of the TEC module. The thermistor NTC then samples the temperature of the TEC module and feeds it back to the temperature comparator amplifier to form a closed-loop control.

10. The low-noise, multi-modulation interface, single-frequency fiber laser driving system according to claim 1, characterized in that: The microcontroller module (1) is composed of an STM32 single-chip microcomputer, a host computer PC electrically connected to the STM32 single-chip microcomputer, a digital-to-analog converter, an IO port, an analog-to-digital converter, a power supply, and FLASH data storage.

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