Device and method for improving wavelength tuning speed of optical parametric oscillator

Abstract

The invention provides a method for improving the wavelength tuning speed of an optical parametric oscillator. The repetition frequency adjustable pump laser outputs preset repetition frequency light, the light enters the frequency selection module after being amplified by the pre-amplification module, and the light is converted into 1 / N times of preset repetition frequency light according to the frequency selection ratio N. Afterwards, the light with the 1 / N times of preset repetition frequency is subjected to power compensation through the amplification module, enters the parameter conversion module through the coupler, generates signal light and idler frequency light, and is partially output by the output module, and the remaining light is sent back to the coupler module through the feedback module, so that intracavity resonance and parameter conversion are realized. When the cavity length of the repetition-frequency adjustable pump laser is changed by dL, the repetition-frequency adjusting amount is df, after the light passes through the frequency selection module, the repetition-frequency variable amount of the light is df / N which is equivalent to the repetition-frequency variable amount of the light in the optical parametric oscillator, and the corresponding cavity length is changed by N * dL, so that the output wavelength is also changed by N times. According to the method, the wavelength tuning speed of the optical parametric oscillator can be greatly improved, and compared with a traditional method, wavelength tuning is achieved faster.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and particularly to a device and method for improving the wavelength tuning speed of an optical parametric oscillator. Background Art

[0002] An optical parametric oscillator is a broadband tunable coherent light source that can effectively overcome the limitations of the emission cross-section of the gain medium and output lasers with wavelengths ranging from ultraviolet to mid-infrared, and is widely used in scientific research and industrial production. For example, high-speed two-photon microscopy, attosecond pulse generation, and nonlinear biomedical imaging, etc. Currently, the optical parametric oscillator is the only method for generating lasers with a wide range of continuously tunable wavelengths. Its principle is to inject a pump light beam into the parametric oscillation cavity, and the pump light undergoes parametric action in the nonlinear frequency conversion medium in the cavity, converting into a signal light and an idler light. The signal light continuously strengthens in the cavity and is output after reaching a certain power.

[0003] The tuning of the output wavelength of the optical parametric oscillator is mainly achieved by changing the phase matching condition of the nonlinear frequency conversion. Usually, it can be achieved by changing the pump wavelength, changing the temperature and angle of the nonlinear frequency conversion medium, or changing the cavity length of the optical parametric oscillator, etc. For the scheme of changing the pump wavelength, the tuning speed is limited by the tuning method of the pump laser, and the wavelength tuning range is limited by the gain medium of the pump laser. In particular, changing the pump wavelength will introduce the risks of mode-locking unlocking and optical parametric oscillator failure. The scheme of changing the medium temperature is the slowest (about dozens of seconds), and it is necessary to wait until the medium reaches temperature equilibrium to achieve the stable output of the optical parametric oscillator; for the scheme of changing the medium angle, the speed is limited by the mechanical adjustment speed (about several seconds), and at the same time, it also faces the risks of affecting the optical path alignment and optical parametric oscillator failure. Changing the length of the parametric oscillation cavity is equivalent to changing the temporal coincidence of the pump pulse and the signal pulse. When the spectra of the signal and pump are expanded in the time domain, the selection of the signal wavelength can be achieved through the above method, but the change of the parametric oscillation cavity length usually adopts a mechanical scheme (the fastest is about several milliseconds), and the speed is still limited. Summary of the Invention

[0004] The present invention is made to solve the above problems, and aims to provide a device and method for improving the wavelength tuning speed of an optical parametric oscillator.

[0005] The present invention provides a device for improving the wavelength tuning speed of an optical parametric oscillator, which has the following characteristics: a repetitively tunable pump laser for outputting pump light with a preset repetition frequency, and the preset repetition frequency is continuously adjustable within a preset range; a pre-amplification module for amplifying the power of the pump light with the preset repetition frequency to a first preset power; a frequency selection module for converting the pump light with the preset repetition frequency into pump light with 1 / N times the preset repetition frequency according to a frequency selection ratio N; an amplification module for amplifying the power of the pump light with 1 / N times the preset repetition frequency to a second preset power; a coupler module for coupling the pump light with the second preset power; a parametric conversion module for receiving the pump light with the second preset power from the coupler module and converting the pump light with the second preset power into signal light and idler light through an optical parametric effect; an output module for outputting the newly generated signal light and idler light and the pump light with the second preset power that has not undergone optical parametric conversion at a percentage A.

[0006] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: a feedback module, the feedback module is respectively connected to the output module and the coupler module, and is used to deliver the signal light and idler light output by the output module at a percentage B to the coupler module. Among them, the coupler module is further used to deliver the signal light and idler light output by the output module at a percentage B and the pump light with the second preset power output by the amplification module to the parametric conversion module, and the sum of percentage A and percentage B is one hundred percent.

[0007] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: among them, the repetitively tunable pump laser is of a fiber structure or a solid structure. When the repetitively tunable pump laser is of a fiber structure, it includes a fiber-type semiconductor saturable absorber, a fiber delay line, a gain fiber, a wavelength division multiplexer, and a fiber-type Bragg grating connected in sequence. The semiconductor laser is connected to the wavelength division multiplexer, and the fiber delay line is used to change the cavity length of the repetitively tunable pump laser; when the repetitively tunable pump laser is of a solid structure, it includes a spatial-type semiconductor saturable absorber mirror, a gain medium, a dichroic mirror, a filter, and a beam splitter connected in sequence. The semiconductor laser is connected to the dichroic mirror, and the spatial-type semiconductor saturable absorber mirror is placed on a piezoelectric ceramic, and the position of the spatial-type semiconductor saturable absorber mirror is changed through the piezoelectric ceramic to change the cavity length of the repetitively tunable pump laser.

[0008] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: Among them, the pre-amplification module includes a semiconductor laser and an isolator, a wavelength division multiplexer, a gain fiber, and an optical fiber coupler connected in sequence. The semiconductor laser is connected to the wavelength division multiplexer. The semiconductor laser emits laser light. The isolator unidirectionally transmits pump light with a preset repetition frequency. The wavelength division multiplexer combines the pump light with a preset repetition frequency and the laser light and then amplifies them through the gain fiber, and then outputs them through the optical fiber coupler.

[0009] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: Among them, the frequency selection module includes a photodetector, an FPGA, an acousto-optic modulation driver, and an acousto-optic modulator connected in sequence. The photodetector converts 1% of the pump light with a preset repetition frequency into an electrical signal. The FPGA measures the repetition frequency of the pump light with a preset repetition frequency at this time and outputs a down-converted electrical signal according to a preset frequency selection ratio N. The acousto-optic modulation driver drives the acousto-optic modulator to modulate 99% of the pump light with a preset repetition frequency according to the electrical signal, generating pump light with 1 / N times the preset repetition frequency.

[0010] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: Among them, the parametric conversion module is a photonic crystal fiber or a nonlinear crystal.

[0011] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: Among them, the output module is one or more of a beam splitter, an optical fiber beam splitter, an optical fiber coupler, and a dichroic mirror.

[0012] In the device for improving the wavelength tuning speed of an optical parametric oscillator provided by the present invention, it may further have the following characteristics: It further includes: an optical parametric oscillator, among which, the optical parametric oscillator is of a fiber structure or a solid structure.

[0013] The present invention provides a method for improving the wavelength tuning speed of an optical parametric oscillator, which has the following characteristics, including: outputting pump light with a preset repetition frequency, and the preset repetition frequency is continuously adjustable within a preset range, amplifying the power of the pump light with a preset repetition frequency to a first preset power, converting the pump light with a preset repetition frequency into pump light with 1 / N times the preset repetition frequency according to a frequency selection ratio N, amplifying the power of the pump light with 1 / N times the preset repetition frequency to a second preset power, coupling the pump light with the second preset power, receiving the pump light with the second preset power of the coupler module and converting the pump light with the second preset power into signal light and idler light through optical parametric effects, and outputting the newly generated signal light and idler light and the pump light with the second preset power that has not undergone optical parametric conversion in a percentage A.

[0014] Functions and effects of the invention

[0015] A device and method for improving the wavelength tuning speed of an optical parametric oscillator. Since it outputs pump light with a preset repetition frequency (set its repetition frequency as: f), amplifies the power of the pump light with the preset repetition frequency to a first preset power, converts the pump light with the preset repetition frequency to pump light with 1 / N times the preset repetition frequency according to the frequency selection ratio N, amplifies the power of the pump light with 1 / N times the preset repetition frequency from the first preset power to a second preset power, and outputs the pump light with the second preset power. It receives the pump light with the second preset power from the coupler module and converts the pump light with the second preset power into signal light and idler light through the optical parametric effect, outputs the newly generated signal light, idler light, and the pump light with the second preset power that has not undergone optical parametric conversion at a percentage A, and at the same time transmits the signal light and idler light at a percentage B to the feedback module. The feedback module sends the signal light and idler light at a percentage B to the coupler module, and the coupler module then sends them into the parametric conversion module. The optical parametric oscillation cavity is composed of a coupler module, a parametric conversion module, an output module, and a feedback module, which can realize the in-cavity resonance of the signal light or the idler light and achieve high-efficiency parametric conversion. Therefore, when the cavity length of the repetition frequency tunable pump laser changes by dL and the repetition frequency adjustment amount is df, after passing through the frequency selection module, the change amount of the repetition frequency of the pump light with 1 / N times the preset repetition frequency is df / N, which is equivalent to the change amount of the repetition frequency of the optical parametric oscillator also being df / N, corresponding to the cavity length of the optical parametric oscillator changing by N×dL. Since the change in the cavity length of the low repetition frequency optical parametric oscillator will cause a change in the output wavelength, only by changing the repetition frequency of the repetition frequency tunable pump laser is equivalent to proportionally changing the cavity length of the optical parametric oscillator, so the output wavelength can be tuned faster compared to the traditional method. The wavelength tuning means of the present invention only focuses on changing the repetition frequency of the repetition frequency tunable pump laser, without the need to adjust other complex factors such as the angle of the devices inside the optical parametric oscillator, greatly reducing the interference such as optical path deflection and mechanical jitter introduced by the change in the optical path collimation situation, and the system operates more stably and reliably. The present invention is not only applicable to all-fiber devices and all-solid devices, but also can perform excellently in hybrid devices constructed by fibers and solids, providing an efficient wavelength tunable solution for more different types of optical parametric oscillators. The present invention can achieve an increase in the wavelength tuning speed of the optical parametric oscillator by several orders of magnitude on the basis of the repetition frequency tuning speed of the existing repetition frequency tunable pump laser. In the present invention, the frequency selection multiple can be flexibly selected according to the application requirements. Through reasonable setting, a substantial increase in the tuning speed of 2 - 3 orders of magnitude can be achieved. When the present invention is used as a light source for coherent Raman imaging, since the pump light and the signal light are output from the same optical fiber, the output of two-color synchronous ultrashort pulses can be realized, simplifying the experimental device and eliminating the need to build additional complex time and space coincidence devices, which not only reduces the cost but also reduces the complexity of the system.When used as a light source for coherent Raman imaging, the present invention can accurately excite different Raman peaks corresponding to a sample through a fast tuning operation. The fast tuning enables the light source to quickly switch among different wavelengths, thereby enabling the acquisition of richer and more accurate sample information. It can also eliminate non-resonant background noise through the spectral signal differences at different wavelengths. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the modules of the device for improving the wavelength tuning speed of the optical parametric oscillator in Embodiments 1-4 of the present invention;

[0017] Figure 2 It is the structural diagram of the all-fiber device in Embodiment 1 of the present invention;

[0018] Figure 3 It is the structural diagram of the all-solid device in Embodiment 2 of the present invention;

[0019] Figure 4 It is the structural diagram of the fiber-pumped solid medium device in Embodiment 3 of the present invention;

[0020] Figure 5 It is the structural diagram of the solid-pumped fiber medium device in Embodiment 4 of the present invention;

[0021] Figure 6 It is the schematic diagram of the structures of four repetition frequency tunable pump lasers in Embodiment 5 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations. The repetition frequency in the present invention refers to the repetition frequency.

[0023] In order to make the technical means, creative features, achieved purposes, and effects of the present invention easy to understand, the following embodiments will specifically describe the device and method for improving the wavelength tuning speed of the optical parametric oscillator of the present invention in conjunction with the drawings.

[0024] Embodiment 1

[0025] Figure 1 It is a schematic diagram of the modules of the device 10 for improving the wavelength tuning speed of the optical parametric oscillator in Embodiments 1-4 of the present invention.

[0026] AsFigure 1 As shown in Figure 1 , the device 10 for improving the wavelength tuning speed of the optical parametric oscillator in Embodiment 1 of the present invention includes: a repetition frequency tunable pump laser 101, a pre-amplification module 102, a frequency selection module 103, an amplification module 104, a coupler module 105, a parametric conversion module 106, an output module 107, and a feedback module 108.

[0027] The device 10 for improving the wavelength tuning speed of the optical parametric oscillator can be divided into different types, namely: all-fiber device, all-solid-state device, fiber-pumped solid medium device, and solid-pumped fiber medium device. In this embodiment, the device 10 for improving the wavelength tuning speed of the optical parametric oscillator is specifically an all-fiber device.

[0028] Figure 2 It is the structure diagram of the all-fiber device in Embodiment 1 of the present invention.

[0029] Figure 2 In the figure, the single dashed line indicates that the light in the circuit is spatial light, the solid line indicates that the light in the circuit is fiber optic light, and the double dashed line indicates that the signal in the circuit is an electrical signal.

[0030] As Figure 1 and Figure 2 shown, among them, the repetition frequency tunable pump laser 101 includes: a fiber-type semiconductor saturable absorber 201, a fiber delay line 202, a first gain fiber 203, a first wavelength division multiplexer 204, a first semiconductor laser 205, and a fiber-type Bragg grating 206.

[0031] The fiber-type semiconductor saturable absorber 201 is sequentially connected to the fiber delay line 202, the first gain fiber 203, the first wavelength division multiplexer 204, and the fiber-type Bragg grating 206, and the first semiconductor laser 205 is connected to the first wavelength division multiplexer 204.

[0032] The fiber delay line 202 is used to change the cavity length of the repetition frequency tunable pump laser 101. By adjusting the fiber delay line 202 to change the cavity length of the repetition frequency tunable pump laser 101, the repetition frequency tunable pump laser 101 can output high-repetition-frequency pump light with a continuously adjustable repetition frequency within a preset range (set its repetition frequency as: f), and f is the preset repetition frequency.

[0033] The pre-amplification module 102 is used to amplify the power of the pump light with a preset repetition frequency to a first preset power, and includes: a first isolator 207, a second semiconductor laser 208, a second wavelength division multiplexer 209, a second gain fiber 210, and a first fiber coupler 211.

[0034] The first isolator 207 is successively connected to the second wavelength division multiplexer 209, the second gain optical fiber 210, and the first optical fiber coupler 211. The first isolator 207 is also connected to the fiber Bragg grating 206. The second semiconductor laser 208 is connected to the second wavelength division multiplexer 209.

[0035] The first isolator 207 unidirectionally transmits the pump light with a preset repetition frequency from the repetition frequency tunable pump laser 101. The second semiconductor laser 208 emits laser light. The second wavelength division multiplexer 209 combines the pump light with the preset repetition frequency unidirectionally transmitted by the first isolator 207 and the laser light, amplifies the combined light through the second gain optical fiber 210, and then outputs the amplified light through the first optical fiber coupler 211. Therefore, the repetition frequency tunable pump laser 101 outputs the pump light with a preset repetition frequency, which is amplified to the first preset power by the pre-amplification module 102 to complete the preliminary amplification so as to complete the subsequent steps.

[0036] The frequency selection module 103 is used to convert the pump light with a preset repetition frequency into the pump light with 1 / N times the preset repetition frequency according to the frequency selection ratio N, and includes: a photodetector 212, an FPGA 213, an acousto-optic modulation driver 214, and an acousto-optic modulator 215.

[0037] The photodetector 212 is successively connected to the FPGA 213, the acousto-optic modulation driver 214, and the acousto-optic modulator 215. The photodetector 212 is also connected to the first optical fiber coupler 211. The acousto-optic modulator 215 is also connected to the first optical fiber coupler 211.

[0038] The photodetector 212 converts 1% of the pump light with the preset repetition frequency into an electrical signal. The FPGA 213 measures the repetition frequency of the pump light with the preset repetition frequency at this time and outputs the down-converted electrical signal according to the preset frequency selection ratio N. The acousto-optic modulation driver 214 drives the acousto-optic modulator 215 to modulate 99% of the pump light with the preset repetition frequency according to the electrical signal to generate the pump light with 1 / N times the preset repetition frequency.

[0039] The amplification module 104 includes: a second isolator 216, a beam combiner 219, a first high-power semiconductor laser 217, a second high-power semiconductor laser 218, and a third gain optical fiber 220.

[0040] The second isolator 216 is successively connected to the beam combiner 219 and the third gain optical fiber 220. The second isolator 216 is also connected to the acousto-optic modulator 215. The beam combiner 219 is also respectively connected to the first high-power semiconductor laser 217 and the second high-power semiconductor laser 218.

[0041] The second isolator 216 enables the unidirectional transmission of pump light with a 1 / N times preset repetition frequency. Both the first high-power semiconductor laser 217 and the second high-power semiconductor laser 218 emit high-power laser light. The beam combiner 219 combines the pump light with a 1 / N times preset repetition frequency and the two beams of high-power laser light and then outputs the combined light. The third gain fiber 220 amplifies the combined light.

[0042] In this embodiment, the coupler module 105 is the third wavelength division multiplexer 221. The parametric conversion module 106 is the photonic crystal fiber 222. The output module 107 is the second fiber coupler 223. The feedback module 108 is the single-mode fiber 224.

[0043] The third wavelength division multiplexer 221 is sequentially connected to the photonic crystal fiber 222 and the second fiber coupler 223. The third wavelength division multiplexer 221 is also connected to the third gain fiber 220. The single-mode fiber 224 is respectively connected to the second fiber coupler 223 and the third wavelength division multiplexer 221.

[0044] The third wavelength division multiplexer 221 combines the light transmitted by the single-mode fiber 224 and the third gain fiber 220. The photonic crystal fiber 222 converts the second preset power pump light into signal light and idler light. The second fiber coupler 223 directly outputs the signal light and idler light with percentage A and the second preset power pump light that has not undergone optical parametric conversion, and transmits the signal light and idler light with percentage B to the single-mode fiber 224. The sum of percentage A and percentage B is one hundred percent. The single-mode fiber 224 transmits the light transmitted to the single-mode fiber 224 back to the third wavelength division multiplexer 221.

[0045] The working principle of the all-fiber device is as follows:

[0046] The repetition frequency tunable pump laser 101 outputs pump light with a preset repetition frequency.

[0047] Specifically, the laser light emitted by the first semiconductor laser 205 sequentially passes through the first wavelength division multiplexer 204, the first gain fiber 203, the fiber delay line 202, reaches the fiber type semiconductor saturable absorber 201, and is then reflected by the fiber type semiconductor saturable absorber 201, and then passes through the fiber delay line 202, the first gain fiber 203, the first wavelength division multiplexer 204 and the fiber type Bragg grating 206 and then outputs. By adjusting the fiber delay line 202 to change the cavity length of the repetition frequency tunable pump laser 101, the repetition frequency tunable pump laser 101 can output high-repetition frequency pump light with a continuously adjustable repetition frequency within a preset range (setting its repetition frequency as: f), and f is the preset repetition frequency.

[0048] The pre-amplification module 102 amplifies the power of the pump light with a preset repetition frequency to a first preset power. Specifically, the pump light with a preset repetition frequency from the repetition frequency tunable pump laser 101 is unidirectionally transmitted by the first isolator 207. The second semiconductor laser 208 emits laser light. The second wavelength division multiplexer 209 combines the pump light with a preset repetition frequency and the laser light and then amplifies them through the second gain fiber 210, and then outputs them through the first fiber coupler 211. The repetition frequency tunable pump laser 101 outputs the pump light with a preset repetition frequency, which is amplified to the first preset power by the pre-amplification module 102 to complete the preliminary amplification so as to complete the subsequent steps.

[0049] The frequency selection module 103 converts the pump light with a preset repetition frequency into pump light with 1 / N times the preset repetition frequency according to the frequency selection ratio N. Specifically, the photodetector 212 converts 1% of the pump light with a preset repetition frequency into an electrical signal and inputs it into the FPGA 213. The FPGA 213 measures the repetition frequency of the pump light with a preset repetition frequency at this time and outputs the down-converted electrical signal according to the preset frequency selection ratio N and then inputs it into the acousto-optic modulation driver 214. The acousto-optic modulation driver 214 drives the acousto-optic modulator 215 according to the electrical signal to modulate 99% of the pump light with a preset repetition frequency, generates pump light with 1 / N times the preset repetition frequency and inputs it into the amplification module 104.

[0050] The amplification module 104 is used to amplify the power of the pump light with 1 / N times the preset repetition frequency to a second preset power. Specifically, the pump light with 1 / N times the preset repetition frequency immediately passes through the second isolator 216 that makes the light unidirectional, and then after being combined with the laser light emitted by the first high-power semiconductor laser 217 and the second high-power semiconductor laser 218 by the beam combiner 219, it is amplified by the third gain fiber 220 to compensate for the reduction of the pump light power caused by the frequency selection module 103.

[0051] The coupler module 105, which is the third wavelength division multiplexer 221 in this embodiment, is used to couple the pump light with the second preset power from the amplification module 104 and the light from the single-mode fiber 224 and output them to the photonic crystal fiber 222.

[0052] The parametric conversion module 106, which is the photonic crystal fiber 222 in this embodiment, receives the pump light with the second preset power from the coupler module 105 and converts the pump light with the second preset power into signal light and idler light through the optical parametric effect and outputs them to the output module 107. Among them, the parametric conversion module 106 is a photonic crystal fiber or a nonlinear crystal.

[0053] An output module 107, which is the second fiber coupler 223 in this embodiment, receives the light from the parametric conversion module 106 and outputs the signal light and idler light of percentage A and the second preset power pump light that has not undergone optical parametric conversion. It outputs the signal light and idler light of percentage B to the single-mode fiber 224, and the sum of percentage A and percentage B is one hundred percent. Among them, the output module is one or more of a beam splitter, a fiber beam splitter, a fiber coupler, and a dichroic mirror.

[0054] A feedback module 108 is used to deliver the signal light and idler light output by the output module 107 at percentage B to the coupler module 105. Specifically, the coupler module 105 is also used to deliver the signal light and idler light output by the output module 107 at percentage B together with the second preset power pump light output by the amplification module 104 to the parametric conversion module 106.

[0055] The change in the cavity length of the low-repetition-rate optical parametric oscillator will cause a change in the output wavelength. Therefore, changing the repetition rate of the repetition-rate tunable pump laser 101 is equivalent to a change in the cavity length of the optical parametric oscillator by N times, and the output wavelength also changes by N times, achieving the purpose of increasing the wavelength tuning speed. The optical parametric oscillation cavity is composed of a third wavelength division multiplexer 221, a photonic crystal fiber 222, a second fiber coupler 223, and a single-mode fiber 224, realizing the intracavity resonance of the signal light or idler light and improving the efficiency of parametric conversion.

[0056] Embodiment 2

[0057] Figure 3 It is the structural diagram of the all-solid-state device in Embodiment 2 of the present invention.

[0058] Figure 3 The single dotted line in the figure indicates that the light in the circuit is spatial light, the solid line indicates that the light in the circuit is fiber light, and the double dotted line indicates that the signal in the circuit is an electrical signal.

[0059] As Figure 1 and Figure 3 shown, the device 10 for increasing the wavelength tuning speed of the optical parametric oscillator in Embodiment 2 of the present invention includes: a repetition-rate tunable pump laser 101, a pre-amplification module 102, a frequency selection module 103, an amplification module 104, a coupler module 105, a parametric conversion module 106, an output module 107, and a feedback module 108.

[0060] The device 10 for increasing the wavelength tuning speed of the optical parametric oscillator can be divided into different types, namely: all-fiber device, all-solid-state device, fiber-pumped solid medium device, and solid-pumped fiber medium device. In this embodiment, the device 10 for increasing the wavelength tuning speed of the optical parametric oscillator is specifically an all-solid-state device.

[0061] Specifically, the repetition frequency tunable pump laser 101 includes: a piezoelectric ceramic 301, a spatial semiconductor saturable absorber mirror SESAM 302, a first gain medium 303, a first dichroic mirror 304, a first semiconductor laser 305, a filter 306, and a first beam splitter 307.

[0062] The spatial semiconductor saturable absorber mirror SESAM 302 is placed on the piezoelectric ceramic 301. The spatial semiconductor saturable absorber mirror SESAM 302 is sequentially connected to the first gain medium 303, the first dichroic mirror 304, the filter 306, and the first beam splitter 307. The first semiconductor laser 305 is connected to the first dichroic mirror 304.

[0063] The first semiconductor laser 305 emits laser light. The first dichroic mirror 304 allows the laser light to pass through. After passing through the first gain medium 303, it is converted into pump light and reaches the spatial semiconductor saturable absorber mirror SESAM 302. Then, the spatial semiconductor saturable absorber mirror SESAM 302 reflects the pump light. After passing through the first gain medium 303 again, it reaches the first dichroic mirror 304. The first dichroic mirror 304 reflects the pump light to the filter 306. The filter 306 allows the pump light with a preset repetition frequency in the required wavelength band to pass through, and finally it is output by the first beam splitter 307.

[0064] The pre-amplification module 102 includes: a first isolator 308, a second semiconductor laser 309, a second dichroic mirror 310, and a second gain medium 311.

[0065] The first isolator 308 is sequentially connected to the second dichroic mirror 310 and the second gain medium 311. The second semiconductor laser 309 is connected to the second dichroic mirror 310. The first isolator 308 is also connected to the first beam splitter 307.

[0066] The first isolator 308 allows the input light to only transmit unidirectionally. The second semiconductor laser 309 emits laser light. The second dichroic mirror 310 combines the pump light with a preset repetition frequency and the laser light. The second gain medium 311 realizes the preliminary amplification of the power of the combined light.

[0067] The frequency selection module 103 includes: a second beam splitter 312, an optical fiber collimator 313, a photodetector 314, an FPGA 315, an acousto-optic modulation driver 316, and an acousto-optic modulator 317.

[0068] The second beam splitter 312 is sequentially connected to the optical fiber collimator 313, the photodetector 314, the FPGA 315, the acousto-optic modulation driver 316, and the acousto-optic modulator 317. The second beam splitter 312 is also respectively connected to the second gain medium 311 and the acousto-optic modulator 317. The acousto-optic modulator 317 is also connected to the first mirror 318.

[0069] The second beam splitter 312 splits the pump light with a preset repetition frequency into two beams. A small part (1%) of the light is converted from spatial light to fiber light by the fiber collimator 313 and sent into the photodetector 314. The photodetector 314 then converts the optical signal into an electrical signal, which is sent into the field programmable gate array FPGA 315. The FPGA 315 measures the repetition frequency of the pump light with the preset repetition frequency at this time according to the electrical signal, and performs a frequency selection operation according to the preset frequency selection ratio N, outputting a down-converted electrical signal. The acousto-optic modulation driver 316 drives the acousto-optic modulator 317 to modulate 99% of the pump light with the preset repetition frequency, generating pump light with 1 / N times the preset repetition frequency.

[0070] The amplification module 104 includes: a second isolator 320, a third dichroic mirror 322, a third semiconductor laser 321, and a third gain medium 323.

[0071] The second isolator 320 is connected to the third dichroic mirror 322 and the third gain medium 323 in sequence. The second isolator 320 is also connected to the second mirror 319, and the third gain medium 323 is also connected to the third mirror 324. The third mirror 324 is connected to the fourth mirror 325.

[0072] The second isolator 320 enables the input light to only transmit in one direction. The third semiconductor laser 321 emits laser light. The third dichroic mirror 322 combines the pump light with 1 / N times the preset repetition frequency and the laser light. The third gain medium 323 amplifies the power of the combined light.

[0073] In this embodiment, the coupler module 105 is the fourth dichroic mirror 326, the parametric conversion module 106 is the nonlinear crystal 327, and the output module 107 is the third beam splitter 328.

[0074] The fourth dichroic mirror 326 is connected to the nonlinear crystal 327, and the nonlinear crystal 327 is connected to the third beam splitter 328. The fourth dichroic mirror 326 is also connected to the fourth mirror 325.

[0075] The fourth dichroic mirror 326 couples the second preset power pump light and the light of the feedback module 108. The nonlinear crystal 327 converts the second preset power pump light into signal light and idler light. The third beam splitter 328 outputs the signal light and idler light with percentage A and the second preset power pump light that has not undergone optical parametric conversion, and outputs the signal light and idler light with percentage B to the feedback module 108. The sum of percentage A and percentage B is one hundred percent.

[0076] The feedback module 108 includes: a fifth mirror 329, a laser delay glass 330, and a sixth mirror 331.

[0077] The fifth mirror 329 is successively connected to the laser delay glass 330 and the sixth mirror 331. The fifth mirror 329 is also connected to the third beam splitter 328, and the sixth mirror 331 is also connected to the fourth dichroic mirror 326.

[0078] The fifth mirror 329 and the sixth mirror 331 reflect light and change its direction.

[0079] The working principle of the all-solid-state device is as follows:

[0080] The repetitively pulsed tunable pump laser 101 outputs pump light with a preset repetition rate.

[0081] Specifically, the laser emitted by the first semiconductor laser 305 passes through the first dichroic mirror 304 and reaches the first gain medium 303 to generate pump light. The pump light is reflected by the spatial semiconductor saturable absorber mirror SESAM 302, passes through the first gain medium 303, and then reaches the first dichroic mirror 304. The first dichroic mirror 304 reflects the pump light to the filter 306, allowing the pump light with a preset repetition rate in the required wavelength band to pass through, and finally outputs the pump light through the first beam splitter 307. By changing the position of the spatial semiconductor saturable absorber mirror SESAM 302 with a piezoelectric ceramic, the cavity length of the repetitively pulsed tunable pump laser 101 is changed, enabling the repetitively pulsed tunable pump laser 101 to output high-repetition-rate pump light with a continuously adjustable repetition rate within a preset range (setting its repetition rate as: f), and f is the preset repetition rate.

[0082] The pre-amplification module 102 amplifies the power of the pump light with a preset repetition rate to a first preset power. Specifically, the pump light with a preset repetition rate output by the repetitively pulsed tunable pump laser 101 is unidirectionally transmitted through the first isolator 308 and enters the pre-amplification module 102. In the pre-amplification module 102, the light output by the second semiconductor laser 309 is combined with the pump light with a preset repetition rate from the repetitively pulsed tunable pump laser 101 at the second dichroic mirror 310, and the combined light beam is transmitted to the second gain medium 311 to achieve preliminary power amplification.

[0083] The frequency selection module 103 converts the pump light with a preset repetition frequency into pump light with 1 / N times the preset repetition frequency according to the frequency selection ratio N. Specifically, the pump light with the preset repetition frequency output from the repetition frequency tunable pump laser 101 is split into two beams by the second beam splitter 312: a small part (1%) of the light is converted from spatial light into fiber light by the fiber collimator 313 and sent into the photodetector 314. The photodetector 314 then converts the optical signal into an electrical signal, and the electrical signal is sent into the field programmable gate array FPGA 315. The FPGA 315 measures the repetition frequency of the pump light with the preset repetition frequency at this time according to the electrical signal, and performs a frequency selection operation according to the preset frequency selection ratio N, outputting a frequency-reduced electrical signal. This electrical signal is then sent into the acousto-optic modulator driver 316 to drive the acousto-optic modulator 317 to achieve frequency selection. The other part of the light (about 99%) passes through the acousto-optic modulator 317 and generates pump light with a repetition frequency of 1 / N times the original preset repetition frequency (the repetition frequency after frequency selection is: f / N). The pump light with 1 / N times the preset repetition frequency enters the amplification module 104 after being reflected and transmitted by the first mirror 318 and the second mirror 319.

[0084] The amplification module 104 is used to amplify the power of the pump light with 1 / N times the preset repetition frequency to a second preset power. Specifically, the pump light with 1 / N times the preset repetition frequency from the frequency selection module 103 passes through the second isolator 320, and the laser emitted by the third semiconductor laser 321 and the pump light with 1 / N times the preset repetition frequency are combined by the third dichroic mirror 322 and enter the third gain medium 323 to amplify the power of the combined light and compensate for the reduction in the pump light power caused by the frequency selection module 103. Then, it is reflected by the third mirror 324 and the fourth mirror 325 again and reaches the coupler module 105.

[0085] The coupler module 105 is the fourth dichroic mirror 326 in this embodiment, and couples the pump light with the second preset power from the amplification module 104, the signal light and the idler light from the feedback module 108 into the parametric conversion module 106.

[0086] The parametric conversion module 106 is the nonlinear crystal 327 in this embodiment, and an optical parametric effect occurs on the nonlinear crystal 327 to generate signal light and idler light. The pump light with the second preset power that has not undergone parametric action, the newly generated signal light and idler light are transmitted to the third beam splitter 328 together.

[0087] The output module 107 is the third beam splitter 328 in this embodiment, directly outputs the signal light and idler light with percentage A and the pump light with the second preset power that has not undergone optical parametric conversion, and at the same time transmits the signal light and idler light with percentage B to the feedback module 108, and the sum of percentage A and percentage B is one hundred percent.

[0088] A feedback module 108 is configured to deliver the signal light and the idler light output by the output module 107 at a percentage B to the coupler module 105. The signal light and the idler light output at the percentage B are reflected back to the fourth dichroic mirror 326 through the sixth mirror 331, and then coupled into the parametric conversion module 106 by the fourth dichroic mirror 326. An optical parametric oscillation cavity is formed by the fourth dichroic mirror 326, the nonlinear crystal 327, the third beam splitter 328, and the feedback module 108, which can achieve intracavity resonance of the signal light or the idler light and improve the efficiency of parametric conversion. Since the change in the cavity length of the low-repetition-rate optical parametric oscillator will cause a change in the output wavelength, changing the repetition rate of the repetition-rate tunable pump laser 101 is equivalent to an N-fold change in the cavity length of the optical parametric oscillator, and the output wavelength also changes by N times, achieving the purpose of improving the wavelength tuning speed of the optical parametric oscillator.

[0089] Embodiment 3

[0090] Figure 4 It is a structural diagram of a fiber-pumped solid medium device in Embodiment 3 of the present invention.

[0091] Figure 4 The single dotted line in the figure indicates that the light in the circuit is spatial light, the solid line indicates that the light in the circuit is fiber light, and the double dotted line indicates that the signal in the circuit is an electrical signal.

[0092] As Figure 1 and Figure 4 shown, the device 10 for improving the wavelength tuning speed of the optical parametric oscillator in Embodiment 3 of the present invention includes: a repetition-rate tunable pump laser 101, a pre-amplification module 102, a frequency selection module 103, an amplification module 104, a coupler module 105, a parametric conversion module 106, an output module 107, and a feedback module 108.

[0093] The device 10 for improving the wavelength tuning speed of the optical parametric oscillator can be divided into different types, namely: all-fiber device, all-solid device, fiber-pumped solid medium device, and solid-pumped fiber medium device. In this embodiment, the device 10 for improving the wavelength tuning speed of the optical parametric oscillator is specifically a fiber-pumped solid medium device.

[0094] Specifically, the repetition-rate tunable pump laser 101 includes: a first fiber coupler 403, a fiber delay line 402, a Bragg grating 401, a wavelength division multiplexer 404, a first semiconductor laser 405, a gain fiber 406, a phase shifter 408, and a second fiber coupler 407.

[0095] The fiber Bragg grating 401 is successively connected to a fiber delay line 402, a first fiber coupler 403, a wavelength division multiplexer 404, a gain fiber 406, and a second fiber coupler 407. The first fiber coupler 403 is also connected to a phase shifter 408, and the phase shifter 408 is also connected to the second fiber coupler 407.

[0096] The fiber delay line 402 is used to change the cavity length of the repetition frequency tunable pump laser 101. By adjusting the fiber delay line 402, the cavity length of the repetition frequency tunable pump laser 101 is changed, so that the repetition frequency tunable pump laser 101 can output high-repetition-frequency pump light with a repetition frequency continuously adjustable within a preset range (set its repetition frequency to: f), and f is the preset repetition frequency.

[0097] The pre-amplification module 102 includes: a first isolator 410, a first dichroic mirror 411, a second semiconductor laser 412, and a first gain medium 413.

[0098] The first isolator 410 is successively connected to the first dichroic mirror 411 and the first gain medium 413, and the second semiconductor laser 412 is connected to the first dichroic mirror 411.

[0099] The first isolator 410 unidirectionally transmits the pump light with the preset repetition frequency from the repetition frequency tunable pump laser 101. The second semiconductor laser 412 emits laser light, and the first dichroic mirror 411 combines the pump light with the preset repetition frequency unidirectionally transmitted by the first isolator 410 and the laser light and amplifies them through the first gain medium 413.

[0100] The frequency selection module 103 includes: a first beam splitter 414, a second fiber collimator 415, a photodetector 416, an FPGA 417, an acousto-optic modulation driver 418, and an acousto-optic modulator 419.

[0101] The first beam splitter 414 is also successively connected to the second fiber collimator 415, the photodetector 416, the FPGA 417, the acousto-optic modulation driver 418, and the acousto-optic modulator 419. The first beam splitter 414 is also directly connected to the acousto-optic modulator 419, and the acousto-optic modulator 419 is successively connected to a first reflector 420, a second reflector 421, and a second isolator 422.

[0102] The first beam splitter 414 divides the pump light with a preset repetition frequency into two beams. A small part (1%) of the light is converted from spatial light to fiber light by the second fiber collimator 415 and sent into the photodetector 416. The photodetector 416 then converts the optical signal into an electrical signal, which is sent into the field programmable gate array FPGA 417. The FPGA 417 measures the repetition frequency of the pump light with the preset repetition frequency at this time according to the electrical signal and outputs a down-converted electrical signal according to the preset frequency selection ratio N. The acousto-optic modulation driver 418 drives the acousto-optic modulator 419 to modulate 99% of the pump light with the preset repetition frequency, generating pump light with 1 / N times the preset repetition frequency.

[0103] The amplification module 104 includes: a second isolator 422, a second dichroic mirror 423, a third semiconductor laser 424, and a second gain medium 425.

[0104] The second isolator 422 is sequentially connected to the second dichroic mirror 423 and the second gain medium 425, and the third semiconductor laser 424 is connected to the second dichroic mirror 423.

[0105] The second isolator 422 enables the input light to only transmit unidirectionally. The third semiconductor laser 424 emits laser light. The second dichroic mirror 423 combines the pump light with 1 / N times the preset repetition frequency and the laser light. The second gain medium 425 amplifies the power of the combined light.

[0106] In this embodiment, the coupler module 105 is a third dichroic mirror 428, the parametric conversion module 106 is a nonlinear crystal 429, and the output module 107 is a second beam splitter 430.

[0107] The third dichroic mirror 428 is connected to the nonlinear crystal 429, the nonlinear crystal 429 is connected to the second beam splitter 430, and the third dichroic mirror 428 is also connected to the fourth mirror 427.

[0108] The feedback module 108 includes: a fifth mirror 431, a laser delay glass 432, and a sixth mirror 433.

[0109] The fifth mirror 431 is sequentially connected to the laser delay glass 432 and the sixth mirror 433. The fifth mirror 431 is also connected to the second beam splitter 430, and the sixth mirror 433 is also connected to the third dichroic mirror 428.

[0110] The fifth mirror 431 and the sixth mirror 433 reflect light to change its direction. The third dichroic mirror 428 couples the second preset power pump light and the light of the feedback module 108. The nonlinear crystal 429 converts the second preset power pump light into signal light and idler light. The second beam splitter 430 outputs the signal light and idler light of percentage A and the second preset power pump light that has not undergone optical parametric conversion, and outputs the signal light and idler light of percentage B to the feedback module 108, where the sum of percentage A and percentage B is one hundred percent.

[0111] The working principle of the fiber-pumped solid medium device is as follows:

[0112] The repetition frequency tunable pump laser 101 outputs pump light with a preset repetition frequency.

[0113] Specifically, the first semiconductor laser 405 emits laser light, which reaches the gain fiber 406 after passing through the wavelength division multiplexer 404 to generate pump light. The pump light passes through the second fiber coupler 407, the phase shifter 408, the first fiber coupler 403, and the fiber delay line 402 to reach the Bragg grating 401. After being reflected by the Bragg grating 401, it passes through the fiber delay line 402, the first fiber coupler 403, the wavelength division multiplexer 404, and the gain fiber 406, and is output from the second fiber coupler 407. By adjusting the fiber delay line 402 to change the cavity length of the repetition frequency tunable pump laser 101, the repetition frequency tunable pump laser 101 can output high-repetition-frequency pump light with a continuously adjustable repetition frequency within a preset range (setting its repetition frequency as: f), and f is the preset repetition frequency.

[0114] The pre-amplification module 102 amplifies the power of the pump light with a preset repetition frequency to the first preset power. Specifically, the light output from the second fiber coupler 407 converts the fiber light into spatial light as output by means of the first fiber collimator 409. The pump light with a preset repetition frequency is unidirectionally transmitted through the first isolator 410 and enters the pre-amplification module 102, where it is combined with the light emitted by the second semiconductor laser 412 at the first dichroic mirror 411, and then enters the first gain medium 413 together to achieve preliminary power amplification.

[0115] The frequency selection module 103 converts the pump light with a preset repetition frequency into pump light with a 1 / N - fold preset repetition frequency according to the frequency selection ratio N. Specifically, the pump light with a preset repetition frequency output from the repetition - frequency - adjustable pump laser 101 is split into two beams by the first beam splitter 414: A small part (1%) is converted from spatial light to fiber - optic light by the second fiber collimator 415 and sent into the photodetector 416. The photodetector then converts the optical signal into an electrical signal, and the electrical signal is sent into the field - programmable gate array FPGA 417. FPGA 417 measures the repetition frequency of the pump light with the preset repetition frequency at this time according to the electrical signal, and performs a frequency selection operation according to the preset frequency selection ratio N, outputting a frequency - reduced electrical signal. This electrical signal is then sent into the acousto - optic modulation driver 418 to drive the acousto - optic modulator 419 to achieve frequency selection. The other part of the light (about 99%) passes through the acousto - optic modulator 419 and generates pump light with a 1 / N - fold preset repetition frequency (the repetition frequency after frequency selection is: f / N).

[0116] The pump light with a 1 / N - fold preset repetition frequency enters the amplification module 104 after being reflected and transmitted by the first mirror 420 and the second mirror 421.

[0117] The amplification module 104 is used to amplify the power of the pump light with a 1 / N - fold preset repetition frequency to a second preset power. Specifically, the pump light with a 1 / N - fold preset repetition frequency from the frequency selection module 103 enters the second dichroic mirror 423 through the second isolator 422. The laser emitted by the third semiconductor laser 424 and the pump light with a 1 / N - fold preset repetition frequency are combined by the second dichroic mirror 423 and enter the second gain medium 425 to amplify the power of the combined light and compensate for the reduction in the pump light power caused by the frequency selection module 103. Then, it is reflected again by the third mirror 426 and the fourth mirror 427 and transmitted to the coupler module 105.

[0118] The coupler module 105, which is the third dichroic mirror 428 in this embodiment, couples the pump light with the second preset power from the amplification module 104, the signal light, and the idler light from the feedback module 108 into the parametric conversion module 106.

[0119] The parametric conversion module 106, which is the nonlinear crystal 429 in this embodiment, undergoes an optical parametric effect on the nonlinear crystal 429 to generate signal light and idler light. The pump light with the second preset power that has not undergone parametric action, the newly generated signal light, and the idler light are transmitted together to the second beam splitter 430.

[0120] The output module 107, which is the second beam splitter 430 in this embodiment, directly outputs the signal light and idler light with a percentage A and the second preset power pump light that has not undergone optical parametric conversion. At the same time, it transmits the signal light and idler light with a percentage B to the feedback module 108, and the sum of percentage A and percentage B is one hundred percent.

[0121] The feedback module 108 is used to deliver the signal light and idler light output by the output module 107 with a percentage B to the coupler module 105. And it reflects the signal light and idler light output with a percentage B back to the third dichroic mirror 428 through the sixth mirror 433, and then the third dichroic mirror 428 couples them into the parametric conversion module. Among them, the third dichroic mirror 428, the nonlinear crystal 429, the second beam splitter 430 and the feedback module 108 form an optical parametric oscillator cavity, which can realize the intracavity resonance of the signal light or idler light and improve the efficiency of parametric conversion. Since the change of the cavity length of the low repetition rate optical parametric oscillator will cause the change of the output wavelength, changing the repetition rate of the repetition rate tunable pump laser 101 is equivalent to the cavity length of the optical parametric oscillator presenting an N-fold change, and the output wavelength also presents an N-fold change, achieving the purpose of improving the wavelength tuning speed of the optical parametric oscillator.

[0122] Embodiment 4

[0123] Figure 5 It is the structural diagram of the solid-pumped fiber medium device in Embodiment 4 of the present invention.

[0124] Figure 5 The single dotted line in the figure indicates that the light in the circuit is spatial light, the solid line indicates that the light in the circuit is fiber light, and the double dotted line indicates that the signal in the circuit is an electrical signal.

[0125] As Figure 1 and Figure 5 shown, the device 10 for improving the wavelength tuning speed of the optical parametric oscillator in Embodiment 4 of the present invention includes: a repetition rate tunable pump laser 101, a preamplifier module 102, a frequency selection module 103, an amplification module 104, a coupler module 105, a parametric conversion module 106, an output module 107 and a feedback module 108.

[0126] The device 10 for improving the wavelength tuning speed of the optical parametric oscillator can be divided into different types, namely: all-fiber device, all-solid device, fiber-pumped solid medium device and solid-pumped fiber medium device. In this embodiment, the device 10 for improving the wavelength tuning speed of the optical parametric oscillator is specifically a solid-pumped fiber medium device.

[0127] Specifically, the repetition frequency tunable pump laser 101 includes: a piezoelectric ceramic 501, a spatial semiconductor saturable absorber mirror SESAM 502, a gain medium 503, a dichroic mirror 504, a first semiconductor laser 505, a filter 506, and a beam splitter 507.

[0128] The spatial semiconductor saturable absorber mirror SESAM 502 is placed on the piezoelectric ceramic 501. The spatial semiconductor saturable absorber mirror SESAM 502 is sequentially connected to the gain medium 503, the dichroic mirror 504, the filter 506, and the beam splitter 507. The first semiconductor laser 505 is connected to the dichroic mirror 504.

[0129] The first semiconductor laser 505 emits laser light. The dichroic mirror 504 allows the laser light to pass through. After passing through the gain medium 503, it is converted into pump light and reaches the spatial semiconductor saturable absorber mirror SESAM 502. Then, the spatial semiconductor saturable absorber mirror SESAM 502 reflects the pump light. After passing through the gain medium 503 again, it reaches the dichroic mirror 504. The dichroic mirror 504 reflects the pump light to the filter 506. The filter 506 allows the pump light with a preset repetition frequency in the required wavelength band to pass through, and finally it is output by the beam splitter 507.

[0130] The preamplifier module 102 includes: a first isolator 509, a second semiconductor laser 510, a first wavelength division multiplexer 511, and a first gain fiber 512.

[0131] The first isolator 509 is sequentially connected to the first wavelength division multiplexer 511 and the first gain fiber 512. The second semiconductor laser 510 is connected to the first wavelength division multiplexer 511.

[0132] The first isolator 509 unidirectionally transmits the pump light with a preset repetition frequency from the repetition frequency tunable pump laser 101. The second semiconductor laser 510 emits laser light. The first wavelength division multiplexer 511 combines the pump light with a preset repetition frequency unidirectionally transmitted by the first isolator 509 and the laser light, and then amplifies them through the first gain fiber 512, and finally outputs through the first fiber coupler 513. Therefore, the pump light with a preset repetition frequency output by the repetition frequency tunable pump laser 101 is amplified to a first preset power by the preamplifier module 102 to complete the preliminary amplification for subsequent steps.

[0133] The frequency selection module 103 includes: a first fiber coupler 513, a photodetector 514, an FPGA 515, an acousto-optic modulation driver 516, and an acousto-optic modulator 517.

[0134] The first optical fiber coupler 513 is also sequentially connected to a photodetector 514, an FPGA 515, an acousto-optic modulation driver 516, and an acousto-optic modulator 517. The first optical fiber coupler 513 is also directly connected to the acousto-optic modulator 517.

[0135] The photodetector 514 converts the pump light with 1% of the preset repetition frequency into an electrical signal. The FPGA 515 measures the repetition frequency of the pump light at this time with the preset repetition frequency and outputs a down-converted electrical signal according to the preset frequency selection ratio N. The acousto-optic modulation driver 516 drives the acousto-optic modulator 517 according to the electrical signal to modulate the pump light with 99% of the preset repetition frequency, generating pump light with 1 / N times the preset repetition frequency.

[0136] The amplification module 104 includes: a second isolator 518, a beam combiner 521, a first high-power semiconductor laser 519, a second high-power semiconductor laser 520, and a second gain fiber 522.

[0137] The second isolator 518 is sequentially connected to the beam combiner 521 and the second gain fiber 522. The second isolator 518 is also connected to the acousto-optic modulator 517. The beam combiner 521 is also respectively connected to the first high-power semiconductor laser 519 and the second high-power semiconductor laser 520.

[0138] The second isolator 518 enables the unidirectional transmission of the pump light with 1 / N times the preset repetition frequency. Both the first high-power semiconductor laser 519 and the second high-power semiconductor laser 520 emit high-power lasers. The beam combiner 521 combines the pump light with 1 / N times the preset repetition frequency and the two high-power lasers and outputs the combined light. The second gain fiber 522 amplifies the combined light.

[0139] In this embodiment, the coupler module 105 is a second wavelength division multiplexer 523, the parametric conversion module 106 is a photonic crystal fiber 524, the output module 107 is a second optical fiber coupler 525, and the feedback module 108 is a single-mode fiber 526.

[0140] The second wavelength division multiplexer 523 is sequentially connected to the photonic crystal fiber 524 and the second optical fiber coupler 525. The second wavelength division multiplexer 523 is also connected to the second gain fiber 522. The single-mode fiber 526 is respectively connected to the second optical fiber coupler 525 and the second wavelength division multiplexer 523.

[0141] The second wavelength division multiplexer 523 combines the light transmitted by the single-mode optical fiber 526 and the second gain optical fiber 522. The photonic crystal fiber 524 converts the second preset power pump light into signal light and idler light. The second fiber coupler 525 directly outputs the signal light and idler light of percentage A and the second preset power pump light that has not undergone optical parametric conversion, and transmits the signal light and idler light of percentage B to the single-mode optical fiber 526. The sum of percentage A and percentage B is one hundred percent. The single-mode optical fiber 526 transports the light transmitted to the single-mode optical fiber 526 back to the second wavelength division multiplexer 523.

[0142] The working principle of the solid-state pumped fiber medium device is as follows:

[0143] The repetitively tunable pump laser 101 outputs pump light with a preset repetition frequency.

[0144] Specifically, the laser emitted by the first semiconductor laser 505 passes through the dichroic mirror 504 and reaches the gain medium 503 to generate pump light. After the pump light reaches the spatial semiconductor saturable absorber mirror SESAM 502, the spatial semiconductor saturable absorber mirror SESAM 502 reflects the pump light and passes it through the gain medium 503 and then reaches the dichroic mirror 504. The dichroic mirror 504 reflects the pump light to the filter 506 to allow the pump light with the preset repetition frequency in the required wavelength band to pass through, and finally outputs it through the first beam splitter 507. By changing the position of the spatial semiconductor saturable absorber mirror SESAM 502 through the piezoelectric ceramic 501, the cavity length of the repetitively tunable pump laser 101 is changed, so that the repetitively tunable pump laser 101 can output high-repetition-frequency pump light with a repetition frequency continuously adjustable within a preset range (setting its repetition frequency as: f), and f is the preset repetition frequency.

[0145] The pre-amplification module 102 amplifies the power of the pump light with a preset repetition frequency to a first preset power. Specifically, the pump light with a preset repetition frequency from the repetitively tunable pump laser 101 is unidirectionally transmitted by the first isolator 509. The second semiconductor laser 510 emits laser light. The first wavelength division multiplexer 511 combines the pump light with a preset repetition frequency and the laser light and amplifies them through the first gain optical fiber 512, and then outputs them through the first fiber coupler 513.

[0146] The frequency selection module 103 converts the pump light with a preset repetition frequency into pump light with 1 / N times the preset repetition frequency according to the frequency selection ratio N. Specifically, the photodetector 514 converts 1% of the pump light with the preset repetition frequency into an electrical signal and inputs it into the FPGA 515. The FPGA 515 measures the repetition frequency of the pump light with the preset repetition frequency at this time and outputs a frequency-down-converted electrical signal according to the preset frequency selection ratio N, and then enters the acousto-optic modulation driver 516. The acousto-optic modulation driver 516 drives the acousto-optic modulator 517 according to the electrical signal to modulate 99% of the pump light with the preset repetition frequency, generates pump light with 1 / N times the preset repetition frequency, and inputs it into the amplification module 104.

[0147] The amplification module 104 is used to amplify the power of the pump light with 1 / N times the preset repetition frequency to a second preset power. Specifically, the pump light with 1 / N times the preset repetition frequency immediately passes through the second isolator 518 that makes the light transmit unidirectionally, and after being combined with the laser emitted by the first high-power semiconductor laser 519 and the second high-power semiconductor laser 520 by the beam combiner 521, it is amplified by the second gain fiber 522 to compensate for the reduction in the pump light power caused by the frequency selection module 103.

[0148] The coupler module 105, which is the second wavelength division multiplexer 523 in this embodiment, is used to couple the second preset power pump light from the amplification module 104 and the light from the single-mode fiber 526, and output it to the photonic crystal fiber 524.

[0149] The parametric conversion module 106, which is the photonic crystal fiber 524 in this embodiment, receives the second preset power pump light from the coupler module 105 and converts the second preset power pump light into signal light and idler light through the optical parametric effect, and outputs it to the output module 107. Among them, the parametric conversion module 106 is a photonic crystal fiber or a nonlinear crystal.

[0150] The output module 107, which is the second fiber coupler 525 in this embodiment, receives the light from the parametric conversion module 106 and outputs the signal light and idler light with percentage A and the second preset power pump light that has not undergone optical parametric conversion, and outputs the signal light and idler light with percentage B to the single-mode fiber 526. The sum of percentage A and percentage B is 100%. Among them, the output module is one or more of a beam splitter, a fiber beam splitter, a fiber coupler, and a dichroic mirror.

[0151] The feedback module 108 is used to transport the signal light and idler light output by the output module 107 with percentage B to the coupler module 105.

[0152] Changing the cavity length of a low-repetition-rate optical parametric oscillator will cause a change in the output wavelength. Therefore, changing the repetition rate of the tunable pump laser 101 with variable repetition rate is equivalent to an N-fold change in the cavity length of the optical parametric oscillator, and the output wavelength also shows an N-fold change, achieving the purpose of increasing the wavelength tuning speed of the optical parametric oscillator. The optical parametric oscillation cavity is composed of a second wavelength division multiplexer 523, a photonic crystal fiber 524, a second fiber coupler 525, and a single-mode fiber 526, realizing the in-cavity resonance of the signal light or the idler light and improving the efficiency of parametric conversion.

[0153] Embodiment 5

[0154] Figure 6 It is a schematic diagram of the structures of four tunable pump lasers with variable repetition rate in Embodiment 5 of the present invention.

[0155] Specifically, for the tunable pump lasers with variable repetition rate in Embodiment 1 and Embodiment 3, in addition to the tunable pump lasers with variable repetition rate used in the embodiments, any one of the tunable pump lasers with variable repetition rate in Figure 6 Schemes a and b can also be selected.

[0156] Figure 6 In the upper left corner, a solid-state laser composed of spatial lenses is adopted, and mode locking is achieved through a semiconductor saturable absorber mirror in the cavity. Inside the tunable pump laser with variable repetition rate, the following main components are included: a semiconductor saturable absorber mirror SESAM 602 placed on a piezoelectric ceramic 601, a gain medium 603, a dichroic mirror 605, a semiconductor laser 604, and a partial reflector 606. Among them, the position of the semiconductor saturable absorber mirror SESAM 602 is changed by the piezoelectric ceramic 601 to change the cavity length of the tunable pump laser with variable repetition rate, enabling the tunable pump laser with variable repetition rate to output high-repetition-rate pump light with a repetition rate continuously adjustable within a preset range.

[0157] Figure 6 In the upper right corner, b adopts a solid-state laser composed of spatial lenses, and mode locking is achieved through a semiconductor saturable absorber mirror in the cavity. Inside the tunable pump laser with variable repetition rate, the following main components are included: a semiconductor saturable absorber mirror 607, a gain medium 608, a dichroic mirror 609, a semiconductor laser 610, an electro-optic modulator 611, and a partial reflector 612. Among them, when the voltage applied to the electro-optic modulator 611 is changed, the refractive index inside the electro-optic modulator 611 will change accordingly, and the change in the refractive index will cause a change in the repetition rate of the pump light passing through the electro-optic modulator 611, enabling the tunable pump laser with variable repetition rate to output high-repetition-rate pump light with a repetition rate quickly and continuously adjustable within a preset range.

[0158] In addition to the repetitively tunable pump lasers used in the embodiments, the repetitively tunable pump lasers of Embodiment 2 and Embodiment 4 may also select Figure 6 any one of the repetitively tunable pump lasers in Schemes c and d.

[0159] Figure 6 In Scheme c at the lower left corner, a fiber laser composed of a fiber Bragg grating (FBG) is adopted, and mode locking is achieved through a nonlinear amplifying loop mirror in the cavity. In the repetitively tunable pump laser, the following components are mainly included: a fiber reflective Bragg grating 613, a semiconductor laser 615, a wavelength division multiplexer 614, a gain fiber 616, a fiber 618 wound around a piezoelectric ceramic 617, and a fiber transmissive Bragg grating 619. Among them, when a voltage is applied across the piezoelectric ceramic material, the material will undergo a slight deformation. By virtue of this characteristic, the length of the fiber wound around it can be changed, enabling the repetitively tunable pump laser to output high-repetition-rate pump light with a repetition rate continuously adjustable within a preset range.

[0160] Figure 6 In Scheme d at the lower right corner, a fiber laser composed of a fiber Bragg grating (FBG) is adopted, and mode locking is achieved through a nonlinear amplifying loop mirror in the cavity. In the repetitively tunable pump laser, the following components are mainly included: a fiber reflective Bragg grating 620, a first semiconductor laser 621, a second semiconductor laser 625, a first wavelength division multiplexer 622, a second wavelength division multiplexer 624, a ytterbium-doped gain fiber 623, an erbium-doped gain fiber 626, and a fiber transmissive Bragg grating 627. The grating of this laser resonates with the laser in the ytterbium-doped band. The second semiconductor laser 625, the second wavelength division multiplexer 624, and the erbium-doped gain fiber 626 form a cavity length modulator. When the second semiconductor laser 625 outputs pump light with different powers into the erbium-doped gain medium 626, the refractive index of the erbium-doped gain fiber 626 will change accordingly, and the change in the refractive index will cause the repetition rate of the pump light passing through the erbium-doped gain fiber 626 to change, enabling the repetitively tunable pump laser to output high-repetition-rate pump light with a repetition rate continuously adjustable within a preset range.

[0161] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A device for improving the wavelength tuning speed of an optical parametric oscillator, characterized in that: include: A repetition frequency adjustable pump laser, used to output pump light with a preset repetition frequency, and the preset repetition frequency is continuously adjustable within a preset range; A pre-amplifier module, used to amplify the power of the pump light of the preset repetition frequency to a first preset power; A frequency selection module, used for converting the pump light of the preset repetition frequency into the pump light of 1 / N times the preset repetition frequency according to the frequency selection ratio N; an amplification module, used to amplify the power of the pump light of 1 / N times the preset repetition frequency to a second preset power; A coupler module, used for coupling a second preset power pump light; A parameter conversion module, used for receiving the second preset power pump light of the coupler module and converting the second preset power pump light into signal light and idler light through an optical parametric effect; The output module is used to output the newly generated signal light and the idler light as well as the second preset power pump light without optical parameter conversion at a percentage A.

2. The device for improving the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: Also includes: A feedback module, wherein the feedback module is connected to the output module and the coupler module respectively, and is used to transmit the signal light and the idler light output by the output module at a percentage B to the coupler module, wherein the coupler module is also used to transmit the signal light and the idler light output by the output module at a percentage B together with the second preset power pump light output by the amplification module to the parametric conversion module, and the sum of the percentage A and the percentage B is one hundred percent.

3. The device for improving the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: in, The repetition frequency adjustable pump laser is a fiber structure or a solid structure. When the repetition frequency adjustable pump laser is of a fiber structure, it includes a fiber-type semiconductor saturable absorber, a fiber delay line, a gain fiber, a wavelength division multiplexer, and a fiber Bragg grating connected in sequence, the semiconductor laser is connected to the wavelength division multiplexer, and the fiber delay line is used to change the cavity length of the repetition frequency adjustable pump laser; When the repetition rate adjustable pump laser is a solid structure, it includes a spatial semiconductor saturable absorber mirror, a gain medium, a dichroic mirror, a filter, and a spectrometer connected in sequence. The semiconductor laser is connected to the dichroic mirror. The spatial semiconductor saturable absorber mirror is placed on a piezoelectric ceramic. The position of the spatial semiconductor saturable absorber mirror is changed by the piezoelectric ceramic, so as to change the cavity length of the repetition rate adjustable pump laser.

4. The device for improving the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: in, The preamplifier module includes a semiconductor laser and an isolator, a wavelength division multiplexer, a gain fiber and a fiber coupler connected in sequence. The semiconductor laser is connected to the wavelength division multiplexer. The semiconductor laser emits laser light. The isolator unidirectionally transmits the pump light of the preset repetition frequency. The wavelength division multiplexer combines the pump light of the preset repetition frequency with the laser light, amplifies them through the gain fiber, and then outputs them through the fiber coupler.

5. The device for improving the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: in, The frequency selection module includes a photodetector, an FPGA, an acousto-optic modulation driver and an acousto-optic modulator connected in sequence. The photodetector converts pump light of 1% of a preset repetition frequency into an electrical signal. The FPGA measures the repetition frequency of the pump light of the preset repetition frequency at this time and outputs a down-converted electrical signal according to a preset frequency selection ratio N. The acousto-optic modulation driver drives the acousto-optic modulator to modulate the pump light of 99% of the preset repetition frequency according to the electrical signal to generate pump light of 1 / N times the preset repetition frequency.

6. The device for increasing the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: in, The parameter conversion module is a photonic crystal fiber or a nonlinear crystal.

7. The device for increasing the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: in, The output module is one or more of a beam splitter, a fiber beam splitter, a fiber coupler, and a dichroic mirror.

8. The device for increasing the wavelength tuning speed of an optical parametric oscillator according to claim 1, characterized in that: Also includes: An optical parametric oscillator, wherein the optical parametric oscillator is a fiber-type structure or a solid-type structure.

9. A method for increasing the wavelength tuning speed of an optical parametric oscillator, characterized in that: include: Outputting a pump light of a preset repetition frequency, wherein the preset repetition frequency is continuously adjustable within a preset range, amplifying the power of the pump light of the preset repetition frequency to a first preset power, converting the pump light of the preset repetition frequency into a pump light of 1 / N times the preset repetition frequency according to a frequency selection ratio N, amplifying the power of the pump light of 1 / N times the preset repetition frequency to a second preset power, coupling the second preset power pump light, receiving the second preset power pump light of the coupler module and converting the second preset power pump light into signal light and idler light through an optical parametric effect, and outputting the newly generated signal light and idler light as a percentage A, as well as the second preset power pump light without optical parametric conversion.

Images