Low-noise single-frequency fiber laser driving system with multiple modulation interfaces

Abstract

The invention provides a low-noise multi-modulation-interface single-frequency optical fiber laser driving system. The low-noise multi-modulation-interface single-frequency optical fiber laser driving system comprises a microcontroller module, a current modulation unit, a piezoelectric ceramic modulation unit, a temperature modulation unit and a single-frequency optical fiber laser, one ends of the current modulation unit, the piezoelectric ceramic modulation unit and the temperature modulation unit are electrically connected with the microcontroller module, and the other ends are electrically connected with the single-frequency fiber laser; the current modulation unit comprises a constant current driving module, a noise suppression module, a first signal source and a current modulation module; the piezoelectric ceramic modulation unit comprises a piezoelectric ceramic driving module, a piezoelectric ceramic module, a piezoelectric ceramic modulation module and a second signal source; the temperature modulation unit comprises a heating module, a temperature control module, a temperature modulation module and a third signal source. According to the invention, the application of multiple modulation interfaces such as current modulation, PZT modulation and temperature modulation of the single-frequency fiber laser is realized, the purpose of providing multiple modulation interfaces for the single-frequency fiber laser can be achieved, the design is simpler, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of laser driving, and in particular to a single-frequency optical fiber laser driving system with a low-noise multi-modulation interface. Background Art

[0002] In gravitational wave detection, high-stability laser interferometers are the key core part, among which frequency-stable lasers are one of the most important components. Single-frequency fiber lasers need to meet three basic conditions to obtain stable laser output: first, population inversion; second, optical resonant cavity length; and third, laser threshold conditions.

[0003] The research is conducted in two aspects: the cavity length of the optical resonant cavity and the threshold of the laser. 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 the electric field. According to this characteristic, it is glued to the internal doped fiber of the fiber laser. By applying different voltages to PZT, the internal doped fiber of the laser will be subjected to different tensions or pressures, thereby changing the cavity length of its resonant cavity or the period of the active phase-shifted fiber grating, and realizing the 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 dramatically, which will affect the modulation frequency performance of PZT. Aiming at the influence of cavity temperature, this paper proposes a temperature modulation technology to perform single longitudinal mode modulation on the laser's resonant cavity temperature, and adds PZT modulation interface and current modulation interface. For low noise processing, this paper adds a noise suppression module to the circuit to realize a single-frequency fiber laser with low noise and multi-modulation interface.

[0004] This low-noise multi-modulation interface can effectively compensate for the nonlinear characteristics of the laser and the influence of temperature changes on the frequency stability, providing highly accurate light source stability. The semiconductor laser driving technology of the low-noise multi-modulation interface provides an important tool for gravitational wave detection. It can improve the frequency stability and control ability of the laser, and enhance the sensitivity and measurement accuracy of the system. Summary of the invention

[0005] In view of 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, temperature modulation and multi-modulation interface 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] In order 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; the current modulation unit, the piezoelectric ceramic modulation unit and the temperature modulation unit are all electrically connected to the microcontroller module at one end and electrically connected to the single-frequency fiber laser at the other end;

[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 a 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 the 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 for power-on.

[0011] The single-frequency fiber laser driving system with 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-R10, a capacitor C3, a second operational amplifier OPA2 and a third operational amplifier OPA3;

[0012] The low-noise power 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 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 non-inverting input end 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 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.

[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 in-phase 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 in-phase 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 in-phase input end of the third operational amplifier OPA3.

[0017] The single-frequency fiber laser driving system with 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 in-phase 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 in-phase 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. An input terminal is provided, 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 and 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-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 low noise and multi-modulation interface, wherein: the temperature modulation module 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;

[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, the temperature is controlled to rise at a certain frequency.

[0022] The single-frequency fiber laser driving system with low noise and 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 converts the temperature signal into a voltage signal through 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 TEC module to heat or cool, and then 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 low noise and 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 driving system of the present invention is reasonably conceived. The design idea of ​​the single-frequency fiber laser driving circuit based on the PZT single modulation interface is used to consider the temperature variables of the single-frequency fiber laser resonant cavity, and a temperature modulation interface and a current modulation interface are added. Not only the way that the piezoelectric ceramic drives the resonant cavity to deform and thus change the cavity length is considered, but also the influence of the resonant cavity temperature on the frequency stabilization is proposed. The temperature modulation interface is used. Temperature modulation is an innovative idea because the temperature will affect the cavity length of the resonant cavity, and the cavity length of the resonant cavity is crucial to the single longitudinal mode output of the laser in terms of single frequency. The change of its cavity length will affect the modulation range of the single longitudinal mode, that is, temperature modulation can promote the frequency stabilization from the aspect of the resonant cavity temperature. In addition, the current modulation interface is added in this article. Compared with the single modulation interface, the frequency fiber laser driving circuit has more functions and lower single-board noise. Compared with the driving circuits of multiple single modulation interfaces, it has more practicality and higher integration, and can realize the function of multi-modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

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

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

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

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

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

[0035] Fig. 9 The schematic diagram of the structure 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 described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention is further explained below in conjunction with specific implementation modes.

[0038] like Figure 1 As shown, the present embodiment provides a single-frequency fiber laser driving system with low noise and multi-modulation interface, 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 Fig. 9 As shown, the microcontroller module 1 is composed of an STM32 single-chip microcomputer and a host computer PC connected to the STM32 single-chip microcomputer, a digital analog converter (i.e., a DAC module), an IO port, an analog digital converter (i.e., an ADC module), a power supply, and a FLASH data storage module. The STM32 single-chip microcomputer is a 32-bit memory microcontroller based on the ARM Cortex-M core, and is produced by ST (STMicroelectronics) with high performance, low power consumption, rich peripherals, and easy development. The power supply module of the STM32 single-chip microcomputer is generally a 3.3V DC power supply. The STM32 single-chip microcomputer has a rich communication interface, which can realize data exchange with other devices. The STM32 single-chip microcomputer is connected and communicated with the ADC module (analog-digital converter) and the DAC module (digital-analog converter) through the communication interface, and the STM32 single-chip microcomputer has a rich peripheral integrated inside, such as an IO port, and the STM32 single-chip microcomputer can output signals through the IO port, and the STM32 single-chip microcomputer can communicate data with the host computer PC to realize data exchange with the host computer PC.

[0041] The constant current driving 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 driving 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; wherein, the constant current driving module 2 receives the control signal output by the current modulation module 9 and then outputs the modulated current to the noise suppression module 3, and then the noise suppression module 3 modulates the single-frequency fiber laser 8 by achieving a low-noise output current through the noise suppression network, so as to control the current output to the single-frequency fiber laser 8.

[0042] like Figure 3 As shown, 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-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 in-phase 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 itself, the excess voltage acts on the N-MOS field effect tube 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, capacitor C1 and a first operational amplifier OPA1; one end of the 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 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 reverse 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 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 capacitor C1 is used as a feedback capacitor to improve the output stability of the first operational amplifier OPA1. At the same time, the output end of the first operational amplifier OPA1 is connected to the non-inverting input end of the third operational amplifier OPA3 of the constant current drive 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, 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.

[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-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, and it 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 to the emitter of the PNP transistor Q3 after being connected in series with resistors R18 and R19 in sequence; 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; and 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 the temperature control module 7 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; wherein 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 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, and the heating module 6 receives the control signal filtered by the LC filter of the low-noise power module. There is a certain linear relationship between the control signal filtered 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 comparison amplifier, a compensation network, a PWM driver, an H-bridge and a TEC module; wherein the TEC module includes a thermoelectric cooler (i.e., a TEC cooling sheet) and a thermistor NTC; one end of the temperature comparison amplifier is electrically connected to the ADC module of the microcontroller module 1, 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 converts the temperature signal into a voltage signal through the thermistor NTC, and the voltage signal is input into this temperature comparison amplifier (differential amplifier) ​​for amplification, and compared with the voltage value corresponding to the set target temperature to generate an error signal, and the output error signal voltage value is output to the PWM driver through the compensation network, such as PID, self-tuning PID and other algorithms to drive the H-bridge, and the H-bridge controls the TEC module to heat or cool, 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.

[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 driving circuit outputs a signal to the constant current driving module 2 through the first signal source. The current output by the constant current driving module 2 and the voltage output by the microcontroller module 1 are in a certain linear relationship. The constant current driving 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 noise output.

[0054] Therefore, in order to achieve the purpose of low noise, the processing can be carried out from 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 using the low noise power supply module can strongly 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, so that 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 improves 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 terminal of the third operational amplifier OPA3, such as Figure 2 Medium R 1 =R 2 ,R 3 =R 4 , 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 driving module 2 can be obtained due to the "virtual short and virtual break" characteristics of the second operational amplifier OPA2. It can be concluded that the current I flowing through the single-frequency fiber laser 8 LD and control voltage signal v out The relationship between.

[0056] The PZT modulation interface consists 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 Fig. 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 5 Circuit of the piezoelectric ceramic driving module 4.

[0058] Figure 5 The A-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 the sixth operational amplifier OPA6 is a power amplifier with high power output, and attention must be paid to its heat dissipation. Moreover, since the amplified gain is determined by the resistor R17 and the resistor R16, attention must be paid 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 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 a 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, and then the output voltage noise is suppressed through the LC filter network of the low-noise power supply module, and 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 in a certain proportional relationship with 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 sheet, 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 constructs a circuit to achieve a 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 closely attached to 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 (the single-frequency fiber laser 8 is mainly composed of a gain medium, an optical resonant cavity and a pump source) inside the single-frequency fiber laser 8 to expand and contract, thereby achieving the effect of changing the cavity length, and finally realizing the 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 not costly.

[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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 single-frequency fiber laser driving system with low noise and multi-modulation interface, characterized in that: 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); the current modulation unit, the piezoelectric ceramic modulation unit and the temperature modulation unit are all electrically connected to the microcontroller module (1) at one end and electrically connected to the single-frequency fiber laser (8) at the other end; The current modulation unit comprises a constant current drive module (2), a noise suppression module (3), a first signal source and a current modulation module (9); the constant current drive 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 drive module (2) to generate a drive current so as to drive the single-frequency fiber laser (8) to work; 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), and then the noise suppression module (3) modulates the single-frequency fiber laser (8) by achieving a low-noise output current through a noise suppression network, 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), 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 a 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 upon startup.

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

4. The single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in claim 2, characterized in that: 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 single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in 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 single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in 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 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, and the other end is electrically connected to the output end of the fourth operational amplifier OPA4; one end of the resistor R14 is electrically connected to the output end of the fourth operational amplifier OPA4, and the other end is electrically connected to the inverting input end of the fifth operational amplifier OPA5; one end of the resistor R15 is electrically connected to the inverting input end of the fifth operational amplifier OPA5, and the other end is electrically connected to the output end of the fifth operational amplifier OPA5; the non-inverting input end of the fifth operational amplifier OPA5 is connected to the power supply VCC, and the output end outputs the modulation signal of the piezoelectric ceramic and is electrically connected to the piezoelectric ceramic drive module (4).

7. The single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in claim 6, characterized in that: The piezoelectric ceramic driving module (4) is composed of resistors R16-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 single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in 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 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 single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in claim 1, characterized in that: The temperature control module (7) comprises a temperature comparison amplifier, a compensation network, a PWM driver, an H-bridge and a TEC module; the TEC module comprises 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 converts the temperature signal into a voltage signal through 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, and the output error signal voltage value is output to the PWM driver through the compensation network to drive the H-bridge, and the H-bridge controls the heating or cooling of the TEC module, and then 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.

10. The single-frequency fiber laser driving system with low noise and multi-modulation interface as claimed in 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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