Titanium sapphire laser control system and method based on FPGA

Abstract

The invention discloses a titanium sapphire laser control system and method based on an FPGA, and relates to the field of titanium sapphire laser control. The system comprises a laser control module, a pumping source, a first plano-concave mirror, a second plano-concave mirror, a first plane mirror, a second plane mirror, a titanium sapphire crystal, a birefringence filter, a piezoelectric rotating motor, piezoelectric ceramics, a piezoelectric control panel, an etalon, a galvanometer motor, a first beam splitter, a photoelectric detector, a second beam splitter and a high-precision wavemeter. The control of the birefringence filter, the etalon and the piezoelectric ceramic is integrated, the laser control module is utilized to realize the automatic tuning of the output wavelength of the Ti sapphire laser, and the birefringence filter, the etalon and the piezoelectric ceramic can be automatically and sequentially controlled as long as a target wavelength value is given, so that the control accuracy is improved. Tuning of the output wavelength of the all-solid-state continuous single-frequency Ti sapphire laser is achieved, and the output wavelength of the laser is accurately controlled.

Description

Technical Field

[0001] The present application relates to the field of titanium sapphire laser control, and in particular to a titanium sapphire laser control system and method based on FPGA. Background Art

[0002] As one of the most promising new generation laser light sources, the all-solid-state continuous single-frequency titanium sapphire laser combines the advantages of traditional solid-state lasers and semiconductor lasers. It has the advantages of small size, continuously tunable frequency, light weight, wide output spectrum, high power, stable performance, good reliability, long life, and high beam quality. It is one of the most important broadband tunable laser light sources and has very wide applications in many important fields such as quantum optics, atomic physics, spectroscopy, biomedicine, quantum communication, gravitational wave detection, and lidar.

[0003] As Chinese universities and institutions continue to conduct research on titanium sapphire lasers, all-solid-state continuous single-frequency titanium sapphire lasers continue to develop in the direction of ultra-high, ultra-fast, ultra-short and ultra-stable, achieving further practical application. A series of locking and control of various parts of the titanium sapphire laser is an important link. At present, people use different means to achieve the control of titanium sapphire lasers, but most of the devices used are manual devices, which have low flexibility, complex internal structure and cumbersome wiring. If the control is invalid, the operator needs to conduct step-by-step detection and analysis and manual maintenance, which places high requirements on the equipment operator. The various signals required by the system also need to be introduced from an external signal source, and an oscilloscope needs to be connected to observe the waveform. This makes the operation of titanium sapphire lasers cumbersome and complicated during use, increases the error rate of manual operation, and brings many inconveniences to scientific research. In addition, the control of intracavity components such as birefringent filters, standard tools, and piezoelectric ceramics is relatively scattered, lacking a highly integrated and automated control system. Therefore, further innovation of titanium sapphire laser control and locking systems has become particularly important. Summary of the invention

[0004] The purpose of this application is to provide a titanium sapphire laser control system and method based on FPGA to improve the control speed and accuracy of the titanium sapphire laser.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a titanium sapphire laser control system based on FPGA, comprising: a laser control module, a pump source, a first plano-concave mirror, a second plano-concave mirror, a first plane mirror, a second plane mirror, a titanium sapphire crystal, a birefringent filter, a piezoelectric rotary motor, a piezoelectric ceramic, a piezoelectric control board, an etalon, a galvanometer motor, a first beam splitter, a photodetector, a second beam splitter and a high-precision wavelength meter;

[0007] The pump source is used to emit laser light; the first plane mirror is located on the outgoing light path of the laser; the titanium sapphire crystal and the second plane concave mirror are sequentially arranged on the outgoing light path of the first plane mirror; the titanium sapphire crystal is arranged between the first plane concave mirror and the second plane concave mirror at the Brewster angle; the piezoelectric rotary motor and the first plane mirror are sequentially arranged on the reflected light path of the second plane concave mirror; the birefringent filter is arranged inside the piezoelectric rotary motor; the piezoelectric control board is connected to the piezoelectric rotary motor; the piezoelectric ceramic is bonded to the first plane mirror; the galvanometer motor and the second plane mirror are sequentially arranged on the reflected light path of the first plane mirror; the etalon is arranged inside the galvanometer motor; the first plane concave mirror is also located on the reflected light path of the second plane mirror; the first beam splitter and the second beam splitter are sequentially arranged on the outgoing light path of the second plane mirror; the photodetector is arranged on the reflected light path of the first beam splitter; the high-precision wavelength meter is arranged on the reflected light path of the second beam splitter;

[0008] The piezoelectric ceramic, the piezoelectric control board, the galvanometer motor, the photodetector and the high-precision wavelength meter are all connected to the laser control module;

[0009] The high-precision wavelength meter is used to read the current wavelength value of the laser output by the titanium sapphire laser; the pump source, the first plano-concave mirror, the second plano-concave mirror, the first plane mirror, the second plane mirror, the titanium sapphire crystal, the birefringent filter, the piezoelectric rotary motor, the piezoelectric ceramic, the etalon and the galvanometer motor constitute the titanium sapphire laser;

[0010] The laser control module controls the piezoelectric control board, the galvanometer motor and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value, so as to adjust the laser wavelength output by the titanium sapphire laser.

[0011] Optionally, the laser control module includes: a computer, an FPGA control board, an analog-to-digital converter, a digital-to-analog converter, a high-voltage amplifier, and a thunderbolt-to-pcie expansion dock;

[0012] The FPGA control board is connected to the computer through the thunderbolt to pcie expansion dock; the analog-to-digital converter and the digital-to-analog converter are installed on the FPGA control board; the analog-to-digital converter is connected to the photodetector; the digital-to-analog converter is respectively connected to the galvanometer motor and the high-voltage amplifier; the computer is connected to the high-precision wavelength meter;

[0013] The computer is used to control the piezoelectric control board, the galvanometer motor and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value.

[0014] Optionally, the piezoelectric ceramic includes: a first piezoelectric ceramic and a second piezoelectric ceramic; the first piezoelectric ceramic, the second piezoelectric ceramic and the first plane mirror are bonded in sequence; the first piezoelectric ceramic is a piezoelectric ceramic with a displacement greater than 20 μm; the second piezoelectric ceramic is a piezoelectric ceramic with a displacement less than 10 μm.

[0015] Optionally, the high-precision wavelength meter is a WS7 series wavelength meter.

[0016] Optionally, the photodetector uses an extra-cavity detection method to perform signal detection.

[0017] Optionally, the high-voltage amplifier is a broadband high-voltage amplifier with a high slew rate; the high slew rate is a slew rate greater than 3V / μs.

[0018] In a second aspect, the present application provides a titanium sapphire laser control method based on FPGA, the titanium sapphire laser control method based on FPGA is applied to the above-mentioned titanium sapphire laser control system based on FPGA, and the titanium sapphire laser control method based on FPGA includes:

[0019] Get the current wavelength value;

[0020] Controlling the piezoelectric rotary motor to rotate until the absolute value of the difference between the current wavelength value and the target wavelength value is less than or equal to a first preset value, and stopping the rotation of the piezoelectric rotary motor;

[0021] Controlling the galvanometer motor to rotate and changing the angle of the etalon until the difference between the current wavelength value and the target wavelength value is greater than 0 and less than or equal to a second preset value, and controlling to lock the etalon; the second preset value is less than the first preset value;

[0022] The first piezoelectric ceramic is controlled to expand and contract until the difference between the current wavelength value and the target wavelength value is less than or equal to a third preset value, and the second piezoelectric ceramic is controlled to stabilize the laser wavelength; the third preset value is less than the second preset value.

[0023] Optionally, the first preset value is 0.4 nm; the second preset value is 0.03 nm; and the third preset value is 0.1 pm.

[0024] According to the specific embodiments provided in this application, this application has the following technical effects:

[0025] The present application provides a titanium sapphire laser control system and method based on FPGA, including: a laser control module, a pump source, a first plano-concave mirror, a second plano-concave mirror, a first plane mirror, a second plane mirror, a titanium sapphire crystal, a birefringent filter, a piezoelectric rotary motor, a piezoelectric ceramic, a piezoelectric control board, an etalon, a galvanometer motor, a first beam splitter, a photodetector, a second beam splitter and a high-precision wavelength meter. The present application integrates the control of the birefringent filter, the etalon and the piezoelectric ceramic, and uses the laser control module to realize the automatic tuning of the output wavelength of the titanium sapphire laser. As long as the target wavelength value is given, the birefringent filter, the etalon and the piezoelectric ceramic are automatically controlled in sequence to realize the automatic tuning of the output wavelength of the all-solid-state continuous single-frequency titanium sapphire laser and accurately control the laser output wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 1 A schematic diagram of a flow chart of a titanium sapphire laser control system based on FPGA provided in one embodiment of the present application;

[0028] Figure 2 It is a schematic diagram of the internal structure of the laser control module of the present application and the interaction with the laser;

[0029] Figure 3 It is a schematic diagram of the control interface of the single-frequency continuous-wave all-solid-state titanium sapphire laser that realizes automatic wide tuning in this application.

[0030] Figure numerals: 1. Pump source; 2. First plano-concave mirror; 3. Titanium sapphire crystal; 4. Second plano-concave mirror; 5. Birefringent filter; 6. Piezoelectric rotary motor; 7-1. First piezoelectric ceramic; 7-2. Second piezoelectric ceramic; 8. First plane mirror; 9. Piezoelectric control board; 10. Standard tool; 11. Galvanometer motor; 12. Laser control module; 12-1. Computer; 12-2. FPGA control board; 12-3. Analog-to-digital converter; 12-4. Digital-to-analog converter; 12-5. High-voltage amplifier; 12-6. Thunderbolt to PCIE expansion dock; 13. Second plane mirror; 14. First beam splitter; 15. Photodetector; 16. Second beam splitter; 17. High-precision wavelength meter. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0033] In an exemplary embodiment, Figure 1 As shown, a titanium sapphire laser control system based on FPGA is provided, including: a laser control module 12, a pump source 1, a first plano-concave mirror 2, a second plano-concave mirror 4, a first plane mirror 8, a second plane mirror 13, a titanium sapphire crystal 3, a birefringent filter 5, a piezoelectric rotary motor 6, piezoelectric ceramics, a piezoelectric control board 9, an etalon 10, a galvanometer motor 11, a first beam splitter 14, a photodetector 15, a second beam splitter 16 and a high-precision wavelength meter 17.

[0034] The pump source 1 is used to emit laser light; the first plane mirror 8 is located on the outgoing optical path of the laser; the titanium sapphire crystal 3 and the second plane-concave mirror 4 are sequentially arranged on the outgoing optical path of the first plane mirror 8; the titanium sapphire crystal 3 is arranged between the first plane-concave mirror 2 and the second plane-concave mirror 4 at the Brewster angle; the piezoelectric rotary motor 6 and the first plane mirror 8 are sequentially arranged on the reflected optical path of the second plane-concave mirror 4; the birefringent filter 5 is arranged inside the piezoelectric rotary motor 6; the piezoelectric control board 9 is connected to the piezoelectric rotary motor 6; the piezoelectric ceramic is bonded to the first plane mirror 8; The galvanometer motor 11 and the second plane mirror 13 are sequentially arranged on the reflected light path of the first plane mirror 8; the standard tool 10 is arranged inside the galvanometer motor 11; the first plano-concave mirror 2 is also located on the reflected light path of the second plane mirror 13; the first beam splitter 14 and the second beam splitter 16 are sequentially arranged on the exit light path of the second plane mirror 13; the photodetector 15 is arranged on the reflected light path of the first beam splitter 14; the high-precision wavelength meter 17 is arranged on the reflected light path of the second beam splitter 16; the high-precision wavelength meter 17 is connected to the laser control module 12 via a USB interface.

[0035] In practical applications, the first plano-concave mirror 2, the second plano-concave mirror 4, the first plane mirror 8 and the second plane mirror 13 constitute a four-mirror ring laser resonant cavity.

[0036] The piezoelectric ceramic, the piezoelectric control board 9, the galvanometer motor 11, the photodetector 15 and the high-precision wavelength meter 17 are all connected to the laser control module 12. The piezoelectric ceramic includes: a first piezoelectric ceramic (long-range piezoelectric ceramic) 7-1 and a second piezoelectric ceramic (short-range piezoelectric ceramic) 7-2; the first piezoelectric ceramic 7-1 is bonded to the second piezoelectric ceramic; the second piezoelectric ceramic 7-2 is bonded to the first plane mirror 8. The first piezoelectric ceramic 7-1 is a piezoelectric ceramic with a displacement greater than 20 μm; the second piezoelectric ceramic 7-2 is a piezoelectric ceramic with a displacement less than 10 μm.

[0037] In practical applications, the piezoelectric control board 9 is connected to the laser control module 12 via serial communication; the galvanometer motor 11 is connected to the laser control module 12 via a BNC line; the first piezoelectric ceramic 7-1 and the second piezoelectric ceramic 7-2 are connected to the laser control module 12 via a BNC line.

[0038] The high-precision wavelength meter 17 is used to read the current wavelength value of the laser emitted by the pump source 1 .

[0039] The laser control module 12 controls the piezoelectric control board 9, the galvanometer motor 11 and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value, so as to adjust the laser wavelength output by the titanium sapphire laser.

[0040] like Figure 2 As shown, the laser control module 12 includes: a computer 12-1, an FPGA control board 12-2, an analog-to-digital converter 12-3, a digital-to-analog converter 12-4, a high-voltage amplifier 12-5 and a thunderbolt to pcie expansion dock 12-6.

[0041] The FPGA control board 12-2 is connected to the computer 12-1 through the thunderbolt to pcie expansion dock 12-6; the analog-digital converter 12-3 and the digital-analog converter 12-4 are installed on the FPGA control board 12-2; the analog-digital converter 12-3 is connected to the photodetector 15; the digital-analog converter 12-4 is respectively connected to the standard tool 10 and the high-voltage amplifier 12-5; the computer 12-1 is connected to the high-precision wavelength meter 17. The control program built into the computer 12-1 collects the current wavelength value of the laser measured by the high-precision wavelength meter 17 in real time, and then the control program sequentially controls the piezoelectric rotary motor 6, the galvanometer motor 11, the long-range piezoelectric ceramics, and the short-range piezoelectric ceramics to achieve large-scale continuous tuning of the output wavelength.

[0042] The computer 12 - 1 is used to control the piezoelectric control board 9 , the galvanometer motor 11 and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value.

[0043] In this embodiment, the FPGA control board 12-2 is an FPGA with PCIe function from Xilinx. The high-precision wavelength meter 17 is a WS7 series wavelength meter from Highfinesse. The piezoelectric control board 9 is a control board for the piezoelectric rotary motor 6AG-PR100 provided by NewPort. The analog-to-digital converter 12-3 is a 12-bit precision AD9238 chip. The digital-to-analog converter 12-4 is a 14-bit precision AD9767 chip. The photodetector 15 uses an extra-cavity detection method for signal detection. The high-voltage amplifier 12-5 is a broadband high-voltage amplifier 12-5 with a high slew rate. The high slew rate is a slew rate greater than 3V / μs.

[0044] The computer control program based on LabVIEW must be used on a computer with a Thunderbolt interface.

[0045] In an exemplary embodiment, the present application provides a titanium sapphire laser control method based on FPGA, the titanium sapphire laser control method based on FPGA is applied to the above-mentioned titanium sapphire laser control system based on FPGA, and the titanium sapphire laser control method based on FPGA includes:

[0046] Get the current wavelength value.

[0047] The piezoelectric rotary motor 6 is controlled to rotate until the absolute value of the difference between the current wavelength value and the target wavelength value is less than or equal to a first preset value, and the rotation of the piezoelectric rotary motor 6 is stopped.

[0048] The galvanometer motor 11 is controlled to rotate and the angle of the etalon 10 is changed until the difference between the current wavelength value and the target wavelength value is greater than 0 and less than or equal to a second preset value, and the etalon 10 is controlled to be locked; the second preset value is less than the first preset value.

[0049] The first piezoelectric ceramic is controlled to expand and contract until the difference between the current wavelength value and the target wavelength value is less than or equal to a third preset value, and the second piezoelectric ceramic is controlled to stabilize the laser wavelength; the third preset value is less than the second preset value.

[0050] As an optional implementation, the first preset value is 0.4 nm; the second preset value is 0.03 nm; and the third preset value is 0.1 pm.

[0051] The FPGA-based titanium sapphire laser control system is used to automatically and accurately control and lock the laser output wavelength.

[0052] The birefringent filter 5 is installed in the piezoelectric rotary motor 6 (AG-PR100) provided by NewPort. This application sets two rotation modes, namely, stepping a certain number of steps and continuous rotation, by calling the motor function provided by NewPort and integrating it into the LabVIEW program. Different speed levels are used to cope with different needs. This application can be divided into two parts, namely, a locking system and a tuning system, for the control of the standard tool 10 and the long-range piezoelectric ceramics and the short-range piezoelectric ceramics. The standard tool 10 is installed in the galvanometer motor 11, and the long-range piezoelectric ceramics and the short-range piezoelectric ceramics are bonded to the cavity mirror. In the locking system, the analog-to-digital converter 12-3 first collects the 1kHz electrical signal detected by the photodetector 15. Since the collected detection signal contains signals of other frequencies, it is not conducive to observing the signal. Therefore, by calling the Xilinx IP core, a bandpass filter with a center frequency of 1kHz is generated to extract the 1kHz signal from the detection signal. A DDS signal generator is used to generate two 1kHz sinusoidal signals with the same frequency and adjustable relative phase inside the FPGA control board 12-2. One signal is loaded onto the galvanometer motor control board as a modulation signal and acts on the standard tool 10. The other signal is mixed with the filtered detection signal as a demodulation signal and passes through a 2kHz low-pass filter. After filtering out the high-frequency part generated by the mixing, the extracted signal is the deviation signal between the transmission peak of the standard tool and the oscillation mode of the laser resonant cavity, that is, the error signal; the error signal is processed by the proportional amplification and integration module to generate a control signal. An input control is set as a DC signal and output through the digital-to-analog converter 12-4. The input value of the control is set to -8191 to +8191 to distinguish the sign of the output voltage, corresponding to a voltage of ±5V. The generated control signal is added to the DC bias signal and the modulation signal by an adder and then loaded onto the control board of the galvanometer motor 11. The computer 12-1 issues a command to lock the standard tool 10 for feedback control of the incident angle of the standard tool 10. In addition, a waveform chart is set on the computer control interface, and the PCIe interface on the FPGA control board 12-2 is inserted into a Thunderbolt to PCIE expansion dock 12-6, and the data is sent to the computer 12-1, so that the modulation and demodulation signal, error signal, and the signal loaded into the standard tool 10 are displayed on the computer 12-1. In the tuning system, a triangular wave signal with adjustable frequency and amplitude is generated through the FPGA control board 12-2, and input into the homemade high-voltage amplifier 12-5 through the digital-to-analog converter 12-4. Then, the control program is used to control the DC bias voltage and the gain of the input signal of the high-voltage amplifier 12-5, so that the high-voltage amplifier 12-5 generates a high-voltage linear scanning signal, which is loaded on the long-range piezoelectric ceramic bonded with a cavity mirror, linearly scans the cavity length of the laser resonant cavity, realizes continuous tuning of the laser, and then realizes laser frequency stabilization through PID control of the short-range piezoelectric ceramic.

[0053] The principle of automatic and precise control of output wavelength is as follows: control the output laser of the titanium sapphire laser, split two laser beams through the first beam splitter 14 and the second beam splitter 16, and the rest is output as the main laser. One part of the split laser beam enters the photodetector 15, and the other part of the split laser beam enters the high-precision wavelength meter 17 for wavelength monitoring. Set a target wavelength value λ M The current wavelength value λ can be read in real time by the high-precision wavelength meter 17 S , control the piezoelectric rotary motor 6 to rotate to change the angle of the birefringent filter 5. According to the intracavity structure and laser characteristics, the output wavelength will change by 0.4nm each time the piezoelectric rotary motor 6 rotates. M -λ S |<=0.4nm, the piezoelectric rotary motor 6 is stopped. Then, the DC bias signal in the locking system is changed to control the mirror motor 11 and change the angle of the etalon 10. When 0<λ is satisfied, M -λ S <=0.03nm, stop changing the DC bias signal and turn on the PI switch to lock the etalon 10. After the etalon 10 is locked, the program changes the DC voltage in the tuning system, connects to the long-range piezoelectric ceramic through the high-voltage amplifier 12-5, controls the expansion and contraction of the long-range piezoelectric ceramic, and thus changes the output wavelength. M -λ S When the DC voltage is less than or equal to 0.1pm, the program will automatically turn on the PID module that controls the short-range piezoelectric ceramics to dynamically stabilize the laser frequency, so that the difference between the laser output wavelength and the set target wavelength is stabilized within the range of 0.1pm.

[0054] Figure 3 It is the control interface of the single-frequency continuous-wave all-solid-state Ti:Sapphire laser that realizes automatic wide tuning in this embodiment. Figure 3 In the figure, area 1 is the wavelength value setting part, including the functions of setting wavelength and reading wavelength; area 2 is the control part of the birefringent filter 5, which can control the piezoelectric rotary motor 6 to step single or continuously with a custom step size; area 3 is the control part of the etalon 10, including a locking module, a modulation and demodulation signal with adjustable amplitude, a DC bias signal, a triangular wave signal with adjustable frequency amplitude and a virtual oscilloscope; area 4 is the control part of the long-range piezoelectric ceramic and the short-range piezoelectric ceramic, including a PID frequency stabilization module and a virtual oscilloscope. Area 5 is the wavelength value automatic control part. After clicking on the automatic calibration, the program will adjust the piezoelectric rotary motor 6 equipped with the birefringent filter 5, the galvanometer motor 11, the long-range piezoelectric ceramic, and the short-range piezoelectric ceramic in turn until the difference between the current wavelength value and the target wavelength value is ≤0.1pm, and the automatic calibration will be stopped. The piezoelectric rotary motor 6 equipped with the birefringent filter 5, the galvanometer motor 11, the long-range piezoelectric ceramic, and the short-range piezoelectric ceramic can also be controlled separately through control to achieve separate automatic calibration of each part. Area 6 is the stop program part.

[0055] This application uses an FPGA control board 12-2 to replace the single-chip microcomputer and each circuit board of the original system, converts the control system based on analog circuits into a program based on digital circuits, and then compiles and burns it into the FPGA control board 12-2 through VIVADO, and uses the PCIe interface on the FPGA control board 12-2 to realize the interaction between the host computer and the slave computer. In the program, the modulation and demodulation signals required for control are generated by the DCS signal generator, a virtual oscilloscope is set, and the collected and sent data are directly displayed on the computer 12-1 through the virtual oscilloscope, thereby replacing the signal generator and oscilloscope required for the original system. A digital bandpass filter with a center frequency of 1kHz is set to extract the 1kHz signal required in the photoelectric detection signal, which is convenient for subsequent observation and locking of the intracavity element standard tool 10. By observing the signal waveform and data sent from the FPGA to the host computer, the input and output signals are adjusted, which is easy to operate and conducive to commercial applications.

[0056] The control of the birefringent filter 5, the standard tool 10, and the piezoelectric ceramics are integrated to achieve automatic and precise control of the laser output wavelength. In addition, the laser control module 12 can read the wavelength value collected by the high-precision wavelength meter 17 and display it in real time in the control program; the piezoelectric rotary motor 6 equipped with the birefringent filter 5 is controlled by the control program; by changing the voltage applied to the long-range piezoelectric ceramic to scan the length of the piezoelectric ceramic, the cavity length of the laser resonant cavity can be continuously adjusted to change the laser output wavelength; the laser frequency stabilization function is set, and a DC signal is output to the high-voltage amplifier 12-5 using the PID control algorithm. The output end of the high-voltage amplifier 12-5 is connected to the laser to control a short-range piezoelectric ceramic in the laser to accurately scan and lock the resonant cavity; the function of automatically controlling the output wavelength is set. Just enter the target wavelength value, and the program will continuously calculate the real-time wavelength value λ M The target wavelength value λ is set by the system S The difference is gradually controlled to gradually control the birefringent filter 5, the etalon 10, and the piezoelectric ceramics, so as to achieve one-key precise control of the output wavelength.

[0057] This application has the following advantages:

[0058] High integration: The three optical components in the titanium sapphire laser are controlled in the same control system, and the laser output wavelength is automatically and accurately controlled through different judgment conditions. The functions of wavelength value reading, signal display and signal generation are integrated into the system, replacing the external oscilloscope and signal source required by the original system.

[0059] Simplified system: The new generation of control systems has fewer external interfaces and internal connections, making them easier to connect, make, and test. When locking the standard tool, there is no need to zero the error signal, which simplifies the locking steps. Using LabVIEW to develop the FPGA control board reduces the amount of code and speeds up the development process.

[0060] Function upgrade: Digital filtering is performed on the collected detection signal to filter out high-frequency interference signals, which is convenient for observing the detection signal and locking the standard tool. The automatic control function is set to achieve one-button precise control of the laser output wavelength.

[0061] This invention can further develop Ti:sapphire lasers in the direction of intelligence, automation, and convenience. It can improve the practicality and commerciality of lasers while reducing the difficulty of use and maintenance, and reducing the cost of manpower and material resources. At the same time, the combination of FPGA hardware, computer algorithms, and laser locking control realizes interdisciplinary cross-disciplinary research, which is a very novel direction with great development potential. It is a great improvement for the in-depth research of all-solid-state continuous single-frequency Ti:sapphire lasers.

[0062] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A titanium sapphire laser control system based on FPGA, characterized in that: include: Laser control module, pump source, first plano-concave mirror, second plano-concave mirror, first plane mirror, second plane mirror, titanium sapphire crystal, birefringent filter, piezoelectric rotary motor, piezoelectric ceramics, piezoelectric control board, etalon, galvanometer motor, first beam splitter, photodetector, second beam splitter and high-precision wavelength meter; The pump source is used to emit laser light; the first plane mirror is located on the outgoing light path of the laser; the titanium sapphire crystal and the second plane concave mirror are sequentially arranged on the outgoing light path of the first plane mirror; the titanium sapphire crystal is arranged between the first plane concave mirror and the second plane concave mirror at the Brewster angle; the piezoelectric rotary motor and the first plane mirror are sequentially arranged on the reflected light path of the second plane concave mirror; the birefringent filter is arranged inside the piezoelectric rotary motor; the piezoelectric control board is connected to the piezoelectric rotary motor; the piezoelectric ceramic is bonded to the first plane mirror; the galvanometer motor and the second plane mirror are sequentially arranged on the reflected light path of the first plane mirror; the etalon is arranged inside the galvanometer motor; the first plane concave mirror is also located on the reflected light path of the second plane mirror; the first beam splitter and the second beam splitter are sequentially arranged on the outgoing light path of the second plane mirror; the photodetector is arranged on the reflected light path of the first beam splitter; the high-precision wavelength meter is arranged on the reflected light path of the second beam splitter; The piezoelectric ceramic, the piezoelectric control board, the galvanometer motor, the photodetector and the high-precision wavelength meter are all connected to the laser control module; The high-precision wavelength meter is used to read the current wavelength value of the laser output by the titanium sapphire laser; the pump source, the first plano-concave mirror, the second plano-concave mirror, the first plane mirror, the second plane mirror, the titanium sapphire crystal, the birefringent filter, the piezoelectric rotary motor, the piezoelectric ceramic, the etalon and the galvanometer motor constitute the titanium sapphire laser; The laser control module controls the piezoelectric control board, the galvanometer motor and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value, so as to adjust the laser wavelength output by the titanium sapphire laser.

2. The FPGA-based titanium sapphire laser control system according to claim 1, characterized in that: The laser control module includes: a computer, an FPGA control board, an analog-to-digital converter, a digital-to-analog converter, a high-voltage amplifier, and a thunderbolt-to-pcie expansion dock; The FPGA control board is connected to the computer through the thunderbolt to pcie expansion dock; the analog-to-digital converter and the digital-to-analog converter are installed on the FPGA control board; the analog-to-digital converter is connected to the photodetector; the digital-to-analog converter is respectively connected to the galvanometer motor and the high-voltage amplifier; the computer is connected to the high-precision wavelength meter; The computer is used to control the piezoelectric control board, the galvanometer motor and the piezoelectric ceramic in sequence according to the current wavelength value and the target wavelength value.

3. The FPGA-based titanium sapphire laser control system according to claim 1, characterized in that: The piezoelectric ceramic includes: a first piezoelectric ceramic and a second piezoelectric ceramic; the first piezoelectric ceramic, the second piezoelectric ceramic and the first plane mirror are bonded in sequence; the first piezoelectric ceramic is a piezoelectric ceramic with a displacement greater than 20 μm; the second piezoelectric ceramic is a piezoelectric ceramic with a displacement less than 10 μm.

4. The FPGA-based Ti:Sapphire laser control system according to claim 1, characterized in that: The high-precision wavelength meter is a WS7 series wavelength meter.

5. The FPGA-based Ti:Sapphire laser control system according to claim 1, characterized in that: The photoelectric detector uses an extra-cavity detection method to perform signal detection.

6. The FPGA-based Ti:Sapphire laser control system according to claim 1, characterized in that: The high-voltage amplifier is a broadband high-voltage amplifier with a high slew rate; the high slew rate is a slew rate greater than 3V / μs.

7. A titanium sapphire laser control method based on FPGA, characterized in that: The FPGA-based titanium sapphire laser control method is applied to the FPGA-based titanium sapphire laser control system according to any one of claims 1 to 6, and the FPGA-based titanium sapphire laser control method includes: Get the current wavelength value; Controlling the piezoelectric rotary motor to rotate until the absolute value of the difference between the current wavelength value and the target wavelength value is less than or equal to a first preset value, and stopping the rotation of the piezoelectric rotary motor; Controlling the galvanometer motor to rotate and changing the angle of the etalon until the difference between the current wavelength value and the target wavelength value is greater than 0 and less than or equal to a second preset value, and controlling to lock the etalon; the second preset value is less than the first preset value; The first piezoelectric ceramic is controlled to expand and contract until the difference between the current wavelength value and the target wavelength value is less than or equal to a third preset value, and the second piezoelectric ceramic is controlled to stabilize the laser wavelength; the third preset value is less than the second preset value.

8. The FPGA-based Ti:Sapphire laser control method according to claim 7, characterized in that: The first preset value is 0.4 nm; the second preset value is 0.03 nm; and the third preset value is 0.1 pm.

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