Pico-second pulse wavelength tunable near-infrared narrow linewidth laser

Abstract

The invention belongs to the technical field of laser, and particularly discloses a picosecond pulse wavelength tunable near-infrared narrow linewidth laser, which is used for providing picosecond pulse laser. The frequency doubling module is used for converting the picosecond pulse laser into pump light through the nonlinear effect of a frequency doubling crystal; the parametric oscillator is used for matching the phase period of the PPLN crystal through temperature control to output signal light, and the length of the resonant cavity is adjusted by combining piezoelectric ceramics, so that the output wavelength range of the signal light is adjusted; and the adjustable optical filter is used for receiving the signal light, and outputting the narrow-spectrum laser corresponding to the signal light by controlling the cavity length of the Fabry-Perot cavity when the intensity of the spectrum transmitted by the cavity length coincides with the transmission spectrum of the Ethernet etalon. According to the invention, tunable wavelength of 800nm-1030nm and narrow-pulse narrow-spectrum laser output are realized.

Description

Technical Field

[0001] This application belongs to the field of laser technology and relates to a laser output that can achieve near-infrared output with tunable wavelength, pulse width less than 100 picoseconds, and spectral width less than 0.3nm. More specifically, it relates to a picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser. Background Technology

[0002] Tunable output lasers with wavelengths of 800nm ​​to 1030nm still face significant technical challenges in current technology. In the semiconductor field, different wavelengths in the range of 1000 to 1650nm can be achieved by doping with indium gallium arsenide systems of different compositions. However, the spectral coverage of a single semiconductor laser chip is limited, generally only around 100nm, making it impossible to achieve large-scale tunable output.

[0003] In terms of narrow pulses, picosecond or femtosecond pulsed lasers are currently easy to achieve, as are ultrafast lasers based on Yb-doped fibers. These types of lasers generally have an output wavelength of more than 1 micrometer and a large spectral width of about 10 nm, allowing for spectral tuning within a small range.

[0004] In existing technologies, laser wavelength conversion devices combining stimulated Raman spectroscopy and sum-frequency nonlinear techniques can convert laser output wavelengths over a wide range. However, this is affected by the tuning wavelength range of the seed laser itself. Furthermore, when using nonlinear sum-frequency techniques for wavelength conversion, coupling and phase matching of the two wavelengths are challenging, and phase mismatch significantly reduces sum-frequency efficiency. Using semiconductor temperature control and sum-frequency techniques to achieve wavelength conversion requires changing both the sum-frequency input wavelength and phase control via temperature to achieve phase matching of the new output wavelength. This results in excessive control variables and makes precise control difficult. In summary, the existing technical solutions have not yet achieved tunable laser output in the 800nm-1030nm wavelength range, as well as narrow pulse and narrow spectrum laser output. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser, aiming to solve the problem that existing technologies have not yet achieved tunability in wavelengths of 800nm~1030nm and narrow pulse and narrow spectrum laser output.

[0006] This application relates to a picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser, comprising: a picosecond pulse laser, a frequency doubling module, a parametric oscillator, and a tunable filter arranged sequentially; Picosecond pulsed lasers are used to provide picosecond pulsed laser light; frequency doubling modules are used to convert picosecond pulsed laser light into pump light through the nonlinear effect of a frequency doubling crystal; The parametric oscillator is used to match the phase and period of the PPLN crystal to the output signal light through temperature control, and the cavity length of the resonant cavity is adjusted by combining piezoelectric ceramics, thereby adjusting the output wavelength range of the signal light. The tunable filter is used to receive signal light. By controlling the cavity length of the Fabry-Perot cavity, when the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the ether etalon standard, the narrow-spectrum laser corresponding to the signal light is output.

[0007] In some implementations, the tunable filter includes a first high-reflectivity mirror, a second high-reflectivity mirror, a second piezoelectric ceramic, and an ether etalon standard. The surfaces of the first and second high-reflectivity mirrors are coated with a high-reflectivity film for signal light with wavelengths of 800nm ​​to 1030nm, forming a Fabry-Perot cavity; a second piezoelectric ceramic is bonded to the bottom of the second high-reflectivity mirror; an ether etalon datum is located inside the Fabry-Perot cavity; The ether etalon standard is used to perform optical spacing of 10 GHz in the wavelength range of the signal light; the second piezoelectric ceramic is used to adjust the cavity length of the Fabry-Perot cavity, and when the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the ether etalon standard, the narrow-spectrum laser corresponding to the signal light is output.

[0008] In some implementations, the parametric oscillator includes a PPLN crystal, a parametric oscillation cavity, and a TEC temperature control box; The PPLN crystal is mounted on the TEC temperature control box and located inside the parametric oscillation chamber. The parametric oscillating cavity is used to receive the pump light transmitted by the frequency doubling module, transmit the signal light to the tunable optical filter, and filter out the idler light for output; PPLN crystals are used to regulate temperature via a TEC temperature control box, so that the phase period matches the wavelength of the signal light, and the pump light is converted into signal light and idler light. The TEC temperature control box is used to regulate the ambient temperature of the PPLN crystal, enabling adjustable wavelength of the signal light.

[0009] In some implementations, the parametric oscillator further includes a temperature sensor and a microcontroller unit; A temperature sensor is installed on the TEC temperature control box and is connected to the microcontroller unit. The temperature sensor is used to monitor the ambient temperature of the PPLN crystal in real time. The microcontroller unit is used to control the temperature of the TEC temperature control box when the ambient temperature exceeds the preset temperature range in order to stabilize the wavelength of the signal light.

[0010] In some embodiments, the parametric oscillation cavity includes a first plano-concave mirror, a second plano-concave mirror, a third plano-concave mirror, a fourth plano-concave mirror, a third high-reflection mirror, a fourth high-reflection mirror, and a first piezoelectric ceramic. The first and second plano-concave mirrors have their concave surfaces facing each other, forming a first resonant cavity; the third and fourth plano-concave mirrors have their concave surfaces facing each other, forming a second resonant cavity; the PPLN crystal is located inside the first resonant cavity; the planar side of the third plano-concave mirror is bonded with a first piezoelectric ceramic. The first, third, and fourth plano-concave mirrors are total internal reflection films; the second high-reflectivity mirror is used to transmit the pump light output from the frequency doubling module to the first plano-concave mirror; the first plano-concave mirror is used to focus the pump light into the PPLN crystal; the second plano-concave mirror is used to output the idler light in the first resonant cavity and reflect the signal light and the remaining pump light to the fourth high-reflectivity mirror; the fourth high-reflectivity mirror is used to transmit the signal light to the tunable light filter and reflect the remaining pump light to the fourth plano-concave mirror; the third and fourth plano-concave mirrors are used to reflect the remaining pump light to the third high-reflectivity mirror, and then into the first resonant cavity; the first piezoelectric ceramic is used to adjust the cavity length of the second resonant cavity, and together with the phase period of the PPLN crystal, controls the wavelength range of the signal light.

[0011] In some embodiments, both the first piezoelectric ceramic and the second piezoelectric ceramic are connected to a microcontroller unit, which is used to control the electrical signals applied to the first piezoelectric ceramic and the second piezoelectric ceramic.

[0012] In some implementations, the femtosecond pulsed laser and the frequency doubling module are integrated into one laser, with an output wavelength of 535nm, a pulse width of 30ps, and an average output power of 4W.

[0013] In some implementations, the phase period of the PPLN crystal is a combination of four periods: 25 micrometers, 25.4 micrometers, 26 micrometers, and 26.4 micrometers.

[0014] In some implementations, the microcontroller unit controls the temperature of the TEC temperature control box within a range of -10°C to 80°C.

[0015] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application provides a picosecond-level pulse wavelength tunable near-infrared narrow-linewidth laser. By controlling the phase and period of the PPLN crystal to match the output signal light through temperature control, and by adjusting the cavity length of the resonant cavity using piezoelectric ceramics, a signal light output with a wavelength tunable from 800nm ​​to 1030nm can be achieved. Furthermore, since the pump light uses a picosecond pulse laser, the pulse width is guaranteed to be at the picosecond level. Based on this, a tunable optical filter is used, employing cavity length adjustment of the Fabry-Perot cavity and an ethereal etalon standard to perform optical comb filtering of the signal light. The Liperlow cavity length is adjusted by piezoelectric ceramics, which may result in some errors in repeatability and stability. The optical filtering of the ether etalon standard has excellent stability. When the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the ether etalon standard, a narrow-spectrum laser is output, which can ensure that the spectral width is less than 0.3 nm. Furthermore, the minimum tuning step size is based on the optical spectral interval of the ether etalon standard during the final wavelength tuning, which is approximately 8 pm at 10 GHz. In summary, this application achieves tunable laser output with narrow pulses and narrow spectra in the wavelength range of 800 nm to 1030 nm. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser provided in an embodiment of this application.

[0017] Figure 2 This is a detailed structural diagram of the parametric oscillator and tunable filter provided in the embodiments of this application.

[0018] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is a picosecond pulsed laser; 2 is a frequency doubling module; 3 is a parametric oscillator; 4 is a tunable light filter; 5-1 is the first plano-concave mirror; 5-2 is the second plano-concave mirror; 6 is a TEC temperature control box; 7 is a PPLN crystal; 8 is a temperature sensor; 9-1 is the first high-reflection mirror; 9-2 is the second high-reflection mirror; 10 is an ethereal etalon; 11 is a piezoelectric ceramic; 12 is an MCU; 13 is the third plano-concave mirror; 14 is the third high-reflection mirror; 15 is the fourth high-reflection mirror; 16 is the fourth plano-concave mirror. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0021] In this application, the terms “first” and “second” are used to distinguish different objects, rather than to describe a specific order of objects.

[0022] In this application, the term "electrical connection" can refer to a direct circuit connection or a signal transmission via a communication protocol.

[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0024] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0025] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0026] PPLN crystal, short for periodically polarized lithium niobate crystal, possesses a strong nonlinear optical coefficient. Its main function is to address the phase mismatch that occurs during nonlinear frequency conversions (such as frequency doubling, sum-frequency conversion, difference-frequency conversion, and optical parametric oscillations) as the input and output light propagate within the crystal. This mismatch prevents the continuous transfer of energy from the pump light to the new frequency. PPLN crystals, through periodic domain inversion, reverse the sign of the nonlinear coefficient each time the phase mismatch accumulates to a certain extent, thereby resetting or pulling back the phase of the output light, resynchronizing it with the pump light. In this application, the 535nm pump light is converted into a wavelength-tunable near-infrared laser. The full name of the TEC temperature control box is thermoelectric cooling temperature control box / control box. It is used in conjunction with PPLN crystals. This is because the optimal operating point of the phase matching condition of PPLN crystals is heavily dependent on temperature. Temperature fluctuations will cause a sharp drop in conversion efficiency. PPLN crystals usually need to be maintained at a constant temperature of 150°C or higher to eliminate harmful photorefractive damage. The TEC temperature control box includes the temperature control box body, thermoelectric cooler, temperature sensor and heat sink; The main body of the temperature control box is a high-precision PID controller, which receives the signal from the temperature sensor, compares it with the target temperature, and calculates the control quantity through proportional-integral-derivative calculation; the thermoelectric cooler is used when a direct current passes through a circuit composed of two different semiconductors, one end absorbs heat and the other end releases heat, and reversing the current direction also reverses the heat flow direction; the temperature sensor is used for real-time temperature feedback.

[0027] After fixing the polarization period of the PPLN crystal, fine tuning of the output near-infrared wavelength can be achieved by finely adjusting the set temperature of the temperature control box. MCU stands for Microcontroller Unit. Piezoelectric ceramics are artificial polycrystalline ceramic materials that have undergone polarization treatment and exhibit the piezoelectric effect, meaning that mechanical energy and electrical energy can be interconverted.

[0028] The first resonant cavity consists of two plano-concave mirrors arranged coaxially with their concave surfaces facing each other and their flat surfaces facing outwards. The incident plano-concave mirror is used to focus the incident pump light into the PPLN crystal, forming a relatively long and appropriately sized optical waist. The exit plano-concave mirror re-collimates the mixed beam (containing pump light, newly generated signal light, and idler light) that has diverged after passing through the PPLN crystal into parallel light.

[0029] The second resonant cavity also consists of two plano-concave mirrors arranged coaxially, with the concave surfaces facing each other and the flat surfaces facing outwards.

[0030] Etherlon etalons are used to select specific wavelength channels with fixed intervals from a broadband light source. A Fabry-Robbin cavity consists of two parallel, highly reflective plane mirrors. Light is reflected multiple times between the two mirrors, causing interference in the transmitted beam. The free spectral range is the wavelength interval between two adjacent transmission peaks.

[0031] The embodiments of this application are described below with reference to the accompanying drawings.

[0032] This application provides a picosecond-level pulse wavelength tunable near-infrared narrow-linewidth laser, comprising a picosecond pulse laser 1, a frequency doubling module 2, a parametric oscillator 3, and a tunable optical filter 4 arranged sequentially. The frequency doubling module 2 doubles the frequency of the 1030nm wavelength PS laser output from the picosecond laser 1 to obtain the input wavelength required by the parametric oscillator 3. Phase matching adjustment within the parametric oscillator 3 yields the desired broadband output light, with an output spectrum of approximately 10nm. The tunable filter acts as a spectral compression device, compressing the 10nm light output from the parametric oscillator to 0.3nm. Thus, by combining these four modules, a narrow pulse and narrow spectral width wavelength tunable output is achieved within the 800~1030nm wavelength range. like Figure 1As shown, picosecond pulsed laser 1 is used to provide pulsed laser output with a wavelength of 1070nm and a pulse width of less than 100 picoseconds; The picosecond pulsed laser 1 generates a pulsed laser and injects it into the frequency doubling module 2 through spatial optical coupling. After passing through the frequency doubling module 2, the wavelength of the output pulsed laser is converted from 1070nm to 535nm through the nonlinear effect of the frequency doubling crystal. Frequency multiplication module 2 outputs a 535nm wavelength picosecond pulse laser, which is injected as pump light into parametric oscillator 3, such as... Figure 2 As shown.

[0033] The parametric oscillator 3 includes a first plano-concave mirror 5-1, a second plano-concave mirror 5-2, a third plano-concave mirror 13, a fourth plano-concave mirror 16, a third high-reflection mirror 14, a fourth high-reflection mirror 15, a PPLN crystal 7, a TEC temperature control box 6, a temperature sensor 8, a first piezoelectric ceramic 11, and an MCU 12. PPLN crystal 7 is disposed on TEC temperature control box 6, located between the first plano-concave mirror 5-1 and the second plano-concave mirror 5-2, the first plano-concave mirror 5-1 and the second plano-concave mirror 5-2 form the first resonant cavity; a temperature sensor 8 is disposed on TEC temperature control box 6; the temperature sensor 8 is connected to MCU12. The third high-reflection mirror 14 and the fourth high-reflection mirror 15 are arranged opposite each other; the concave surfaces of the third plano-concave mirror 13 and the fourth plano-concave mirror 16 are arranged opposite each other to form a second resonant cavity; a first piezoelectric ceramic 11 is provided on the planar side of the third plano-concave mirror 13; the piezoelectric ceramic 11 is connected to the MCU 12; the first pair of plano-concave mirrors 5, the third high-reflection mirror 14, the fourth high-reflection mirror 15 and the second pair of plano-concave mirrors constitute a parametric oscillation cavity; The first plano-concave mirror 5-1, the third plano-concave mirror 13, and the fourth plano-concave mirror 16 require coating treatment, such as gold film or other total reflection film; the second high-reflectivity mirror 14 is coated to transmit at 535nm and reflect other wavelengths, and is used to transmit the pump light output from the frequency doubling module 2 into the first plano-concave mirror 5-1; the first plano-concave mirror 5-1 is used to focus the pump light and transmit it into the PPLN crystal; the PPLN crystal 7 is a quasi-phase-matched crystal, which outputs the signal light wavelength by matching the phase period and performing wavelength tuning. The phase period matching of the PPLN crystal 7 is controlled by temperature, and the MCU12 performs closed-loop control of the TEC temperature control box 6 and the temperature sensor 8. When the temperature sensor 8 detects that the temperature is too high, the MCU12 controls the temperature of the TEC temperature control box 6 to stabilize the temperature environment and stabilize the wavelength output; The second plano-concave mirror 5-2 is coated to transmit light beams with wavelengths above 1030nm (idle light), and acts as a high-reflectivity film for light beams in other wavelength bands. It is used to output the idle light in the first resonant cavity and reflect the signal light and the remaining pump light to the fourth high-reflectivity mirror. The fourth high-reflectivity mirror 15 is required to transmit light from 800nm ​​to 1030nm and reflect light of other wavelengths. It is used to output the signal light to the tunable filter and reflect the remaining pump light to the fourth plano-concave mirror. The fourth plano-concave mirror 16 is used to oscillate the remaining pump light in the second resonant cavity, and reflect it through the third plano-concave mirror 13 to the third high-reflectivity mirror 14, returning to the first resonant cavity. The bottom of the third plano-concave mirror 13 is bonded to the piezoelectric ceramic 11. The cavity length of the second resonant cavity is finely adjusted by the first piezoelectric ceramic 11, and the output wavelength range is determined together with the phase period of the PPLN crystal 7. After the above optical modulation, the output spectrum of the parametric oscillator 3 is relatively wide, about 10nm, but the wavelength is tunable. In order to compress the spectral width, an adjustable filter 4 needs to be added after the parametric oscillator 3. The adjustable filter 4 includes a first high-reflection mirror 9-1, a second high-reflection mirror 9-2, an ether etalon standard 10, and a second piezoelectric ceramic 17; The etheric standard etalon 10 is located between the first high-reflection mirror 9-1 and the second high-reflection mirror 9-2; the second piezoelectric ceramic 17 is bonded to the bottom of the second high-reflection mirror 9-2; The surfaces of the first high-reflectivity mirror 9-1 and the second high-reflectivity mirror 9-2 need to be coated with a high-reflectivity film for the 800nm~1030nm wavelength range. The Etherlon etalon design uses a 10GHz optical spacing in the 800nm~1030nm wavelength range. The second high-reflectivity mirror 9-2 is bonded and encapsulated with the second piezoelectric ceramic 17, and the cavity length of the Fabry-Perot cavity (FP cavity) composed of the first high-reflectivity mirror 9-1 and the second high-reflectivity mirror 9-2 is precisely controlled by the second piezoelectric ceramic 17. When the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the Etherlon etalon, the corresponding narrow-spectrum laser is output. The control of the second piezoelectric ceramic 17 is completed by the MCU 12.

[0034] Example The femtosecond pulsed laser 1 and the frequency doubling module 2 can be an integrated laser module with the following specific parameters: output wavelength of 535nm; pulse width of 30ps; and average output power of 4W. The specific parameters of the PPLN crystal are as follows: Size: 10mm 1mm 2mm; Variable period matching is used, with four periods of 25 micrometers, 25.4 micrometers, 26 micrometers and 26.4 micrometers combined together, for a total of 4 periods; The first plano-concave mirror 5-1 and the third plano-concave mirror 13 are coated with a total internal reflection gold film, the third high-reflection mirror 14 is coated with a dielectric film, which transmits at 535nm and reflects other wavelengths, and the fourth high-reflection mirror 15 is coated with a dielectric film, which transmits at 800nm~1030nm and reflects other wavelengths. The MCU12 microcontroller unit is used to control the temperature of the TEC temperature control box. The temperature control range is -10~80℃. The TEC temperature is pre-controlled to 30℃. The pump light output from the frequency multiplier module 2 is injected into the parametric oscillator through the third high-reflection mirror 14. The pump light wavelength is parametrically converted by the PPLN crystal 7. During this process, the MCU12, TEC temperature control box and temperature sensor 8 are used for closed-loop control to regulate the output wavelength. The average power of the injected pump is 4 watts. The relationship between the center wavelength of the output light of parametric oscillator 3 and the TEC set temperature was plotted using a spectrometer, and Table 1 was obtained; Table 1

[0035] The positional relationship between the output wavelength of the tunable filter and the second piezoelectric ceramic 17 was marked using a spectrometer, and Table 2 was obtained; Table 2

[0036] Based on the relationship between Table 1 and Table 2, the relationship between the output wavelength and the control quantity between the TEC control temperature and the piezoelectric ceramic 11 is obtained. The spectral width is 0.3 nm, the pulse width is about 60 ps, ​​and the output power is 50 milliwatts when the light is injected with a pump power of 4 watts.

[0037] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0038] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0039] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser, characterized in that, include: The picosecond pulse laser, frequency doubling module, parametric oscillator, and tunable filter are set in sequence. Picosecond pulsed lasers are used to provide picosecond pulsed lasers; The frequency doubling module is used to convert picosecond pulsed laser light into pump light through the nonlinear effect of the frequency doubling crystal; The parametric oscillator is used to match the phase and period of the PPLN crystal to the output signal light through temperature control, and the cavity length of the resonant cavity is adjusted by combining piezoelectric ceramics, thereby adjusting the output wavelength range of the signal light. The tunable filter is used to receive signal light. By controlling the cavity length of the Fabry-Perot cavity, when the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the ether etalon standard, the narrow-spectrum laser corresponding to the signal light is output.

2. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 1, characterized in that, The tunable filter includes a first high-reflectivity mirror, a second high-reflectivity mirror, a second piezoelectric ceramic, and an ether etalon standard; The surfaces of the first and second high-reflectivity mirrors are coated with a high-reflectivity film for signal light with wavelengths of 800nm ​​to 1030nm, forming a Fabry-Perot cavity; a second piezoelectric ceramic is bonded to the bottom of the second high-reflectivity mirror; an ether etalon datum is located inside the Fabry-Perot cavity; The ether etalon standard is used to perform optical spacing of 10 GHz in the wavelength range of the signal light; the second piezoelectric ceramic is used to adjust the cavity length of the Fabry-Perot cavity, and when the spectral intensity transmitted through the cavity length coincides with the transmission spectrum of the ether etalon standard, the narrow-spectrum laser corresponding to the signal light is output.

3. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 2, characterized in that, The parametric oscillator includes a PPLN crystal, a parametric oscillation cavity, and a TEC temperature control box; The PPLN crystal is mounted on the TEC temperature control box and located inside the parametric oscillation chamber. The parametric oscillating cavity is used to receive the pump light transmitted by the frequency doubling module, transmit the signal light to the tunable optical filter, and filter out the idler light for output; PPLN crystals are used to regulate temperature via a TEC temperature control box, so that the phase period matches the wavelength of the signal light, and the pump light is converted into signal light and idler light. The TEC temperature control box is used to regulate the ambient temperature of the PPLN crystal, enabling adjustable wavelength of the signal light.

4. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 3, characterized in that, The parametric oscillator also includes a temperature sensor and a microcontroller unit; A temperature sensor is installed on the TEC temperature control box and is connected to the microcontroller unit. The temperature sensor is used to monitor the ambient temperature of the PPLN crystal in real time. The microcontroller unit is used to control the temperature of the TEC temperature control box when the ambient temperature exceeds the preset temperature range in order to stabilize the wavelength of the signal light.

5. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 4, characterized in that, The parametric oscillation cavity includes a first plano-concave mirror, a second plano-concave mirror, a third plano-concave mirror, a fourth plano-concave mirror, a third high-reflection mirror, a fourth high-reflection mirror, and a first piezoelectric ceramic. The first, third, and fourth plano-concave mirrors are total internal reflection films; the second high-reflectivity mirror is used to transmit the pump light output from the frequency doubling module to the first plano-concave mirror; the first plano-concave mirror is used to focus the pump light into the PPLN crystal; the second plano-concave mirror is used to output the idler light in the first resonant cavity and reflect the signal light and the remaining pump light to the fourth high-reflectivity mirror; the fourth high-reflectivity mirror is used to transmit the signal light to the tunable light filter and reflect the remaining pump light to the fourth plano-concave mirror; the third and fourth plano-concave mirrors are used to reflect the remaining pump light to the third high-reflectivity mirror, and then into the first resonant cavity; the first piezoelectric ceramic is used to adjust the cavity length of the second resonant cavity, and together with the phase period of the PPLN crystal, controls the wavelength range of the signal light.

6. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 5, characterized in that, Both the first and second piezoelectric ceramics are connected to a microcontroller unit, which is used to control the electrical signals applied to the first and second piezoelectric ceramics.

7. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to any one of claims 1 to 6, characterized in that, The femtosecond pulsed laser and frequency doubling module are integrated into one laser, with an output wavelength of 535nm, a pulse width of 30ps, and an average output power of 4W.

8. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to any one of claims 1 to 6, characterized in that, The phase period of the PPLN crystal is a combination of four periods: 25 micrometers, 25.4 micrometers, 26 micrometers, and 26.4 micrometers.

9. The picosecond-level pulse wavelength tunable near-infrared narrow linewidth laser according to claim 4, characterized in that, The microcontroller unit controls the temperature of the TEC temperature control box within a range of -10℃ to 80℃.

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