Dual-wavelength tunable all-solid-state mid- and far-infrared laser

Abstract

The present disclosure provides a kind of dual-wavelength tunable all-solid-state mid-infrared laser, it relates to laser technical field, to solve the technical problems that high-performance dual-wavelength 3 μm band laser and its pump generation mid-infrared band laser are difficult to obtain in prior art.The mid-infrared laser includes: erbium-doped laser and optical parametric oscillator, the erbium-doped laser is used to provide dual-wavelength 3 μm band pulsed laser, wherein, erbium-doped laser includes: pump source, erbium-doped laser medium, gain modulation device, high reflection mirror and output mirror;Optical parametric oscillator is used under the pumping action of dual-wavelength pulsed laser in 3 μm band, and the mid-infrared laser of dual-wavelength output is obtained.The mid-infrared laser is simple in structure, easy to use, can obtain tunable dual-wavelength mid-infrared pulsed laser with high beam quality, meets the light source demand of differential absorption laser radar remote sensing toxic gas and photoelectric countermeasure.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of lasers, and more particularly, to a dual-wavelength tunable all-solid-state mid-far infrared laser. BACKGROUND

[0002] The 3-μm band laser, 3-5-μm mid-infrared laser and 8-12-μm long-infrared laser are all in the atmospheric transmission window, and have a wide application prospect in the fields of laser radar, spectroscopy, atmospheric environment detection, scientific research and photoelectric countermeasure. Remote sensing of toxic and harmful gases in the atmosphere is an important part of environmental quality monitoring. The mid-infrared and long-infrared bands both cover the characteristic absorption peaks of various toxic gases, and the laser of the bands is usually used for toxic gas detection. The differential absorption laser radar (DIAL) system based on differential absorption spectroscopy technology has the characteristics of active detection, long working distance and high detection precision, and has been widely used in the measurement and monitoring of various toxic gases. The DIAL usually uses a tunable laser as a light source, and needs to continuously emit two laser pulses of different wavelengths during measurement, which puts forward higher requirements for the tuning range and tuning speed of the laser. The dual-wavelength tunable mid-far infrared laser can simultaneously output mid-infrared laser of two wavelengths and long-infrared laser of two wavelengths, which is of great significance to improve the detection precision and sensitivity of multi-component toxic gases.

[0003] In recent years, the laser beam with simultaneous output of mid-infrared and long-infrared has a wide application value in the fields of laser target indication and photoelectric countermeasure. The 3-μm photon can be converted into 8-12-μm long-infrared idler light and 4.8-4.0-μm mid-infrared signal light through nonlinear frequency conversion technology. Therefore, the dual-wavelength laser of 3-μm band with high beam quality is the basis for obtaining the dual-wavelength tunable mid-infrared and long-infrared laser beam, and in addition, the 3-μm band laser is also near the water absorption band and is a commonly used medical light source. However, the related technology for obtaining high-performance dual-wavelength 3-μm band laser and its pumped mid-far infrared laser is still in a blank state. SUMMARY

[0004] Therefore, the present disclosure provides a dual-wavelength tunable all-solid-state mid-far infrared laser to solve the technical problem that the prior art is difficult to obtain high-performance dual-wavelength 3-μm band laser and its pumped mid-far infrared laser.

[0005] One aspect of the present disclosure provides a dual-wavelength tunable all-solid-state mid-far infrared laser, comprising: an erbium-doped laser for providing a dual-wavelength specified band pulsed laser, wherein the erbium-doped laser comprises: a pump source for providing pump light; an erbium-doped laser medium comprising a first laser medium and a second laser medium for generating a dual-wavelength specified band laser under the pumping action of the pump light; a gain modulation device for obtaining the dual-wavelength specified band pulsed laser by adjusting the loss state of the resonant cavity; a high-reflectivity mirror for reflecting the dual-wavelength specified band pulsed laser; an output mirror for outputting the dual-wavelength specified band pulsed laser in cooperation with the high-reflectivity mirror; and an optical parametric oscillator for obtaining dual-wavelength mid-wave infrared laser and dual-wavelength long-wave infrared laser under the pumping action of the dual-wavelength specified band pulsed laser.

[0006] According to an embodiment of the present disclosure, the first laser medium and the second laser medium are both anisotropic erbium-doped laser media, and the stimulated emission peaks thereof correspond to the dual-wavelength specified band, respectively.

[0007] According to an embodiment of the present disclosure, the pump source is configured in a double-end pumping structure, comprising: a first pump source arranged at one end close to the first laser medium for pumping the first laser medium, the output spectral line of the first pump source matching the absorption spectral line of the first laser medium; and a second pump source arranged at one end close to the second laser medium for pumping the second laser medium, the output spectral line of the second pump source matching the absorption spectral line of the second laser medium; wherein by adjusting the pump power of the double-end pumping structure, the laser output power ratio of the dual-wavelength specified band pulsed laser can be adjusted.

[0008] According to an embodiment of the present disclosure, the gain modulation device is configured as any one of an electro-optic Q-switching element, an acousto-optic Q-switching element or a passive Q-switching medium; wherein the electro-optic Q-switching element comprises: a first polarizer for determining the polarization state of the dual-wavelength specified band laser; a quarter-wave plate for adjusting the polarization direction of the dual-wavelength specified band laser so that the dual-wavelength specified band laser can pass through the first polarizer in a determined polarization state; and an electro-optic Q-switch for obtaining the dual-wavelength specified band pulsed laser by adjusting the loss state of the resonant cavity.

[0009] According to an embodiment of the present disclosure, the optical parametric oscillator comprises: a first nonlinear crystal for realizing frequency nonlinear transformation of the dual-wavelength specified band pulsed laser; an input cavity mirror arranged at the input end of the first nonlinear crystal for inputting the dual-wavelength specified band pulsed laser; and an output cavity mirror arranged at the output end of the first nonlinear crystal and cooperating with the input cavity mirror to form an optical parametric oscillation resonant cavity for outputting the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser.

[0010] According to the embodiment of the present disclosure, the first beam splitter is arranged between the first pump source and the first laser medium, and is configured to transmit the pump light provided by the first pump source and reflect the dual-wavelength specified-band laser generated by the erbium-doped laser medium.

[0011] According to the embodiment of the present disclosure, the third beam splitter is arranged between the output mirror and the input mirror, and is configured to reflect the dual-wavelength specified-band pulsed laser generated by the erbium-doped laser to the first nonlinear crystal; the fourth beam splitter is arranged at one end of the output mirror, and is configured to reflect the dual-wavelength specified-band pulsed laser remaining after passing through the first nonlinear crystal, and transmit the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator; and the fifth beam splitter is arranged at one end of the fourth beam splitter, and is configured to reflect the dual-wavelength mid-wave infrared laser, and transmit the dual-wavelength long-wave infrared laser.

[0012] According to the embodiment of the present disclosure, the optical parametric amplifier is arranged at the output end of the optical parametric oscillator, and is configured to amplify the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator.

[0013] According to the embodiment of the present disclosure, the adjustable attenuator is arranged at the output end of the erbium-doped laser, and is configured to adjust the laser power of the dual-wavelength specified-band pulsed laser injected into the optical parametric oscillator and the optical parametric amplifier, and includes: a first half-wave plate configured to adjust the polarization direction of the dual-wavelength specified-band laser; and a second polarizer configured to divide the dual-wavelength specified-band pulsed laser into two paths, one of which is used to pump the optical parametric oscillator, and the other of which is used to pump the optical parametric amplifier.

[0014] According to the embodiment of the present disclosure, the optical parametric amplifier includes: a beam combiner arranged at the output end of the optical parametric oscillator, and configured to combine the dual-wavelength specified-band pulsed laser and the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator; and a second nonlinear crystal configured to amplify the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator under the pumping action of the combined dual-wavelength specified-band pulsed laser.

[0015] The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiment of the present disclosure has at least the following beneficial effects:

[0016] (1) The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiment of the present disclosure adopts two kinds of erbium-doped laser medium, combines gain modulation technology, realizes the output of dual-wavelength 3 μm band pulse laser, and then adopts the dual-wavelength 3 μm band pulse laser to pump a nonlinear crystal, based on single-resonant optical parametric oscillation technology, realizes tunable dual-wavelength laser in the mid-long wave infrared band with good beam quality. The mid-far infrared laser has simple structure and is convenient to use, can obtain tunable dual-wavelength mid-far infrared laser with high beam quality, and meets the light source demand of differential absorption laser radar remote sensing of toxic gas and photoelectric countermeasure.

[0017] (2) The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiment of the present disclosure adopts two pump sources to pump erbium-doped laser medium, realizes dual-wavelength laser output, and can realize continuous adjustment of the power / energy ratio of dual-wavelength laser output by directly controlling the pump power of the two pump sources.

[0018] (3) The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiment of the present disclosure adopts the cascade pumping mode of "LD pump source→erbium-doped laser→optical parametric oscillator→optical parametric amplifier", ensures a higher mode matching factor of the resonant cavity, and obtains dual-wavelength tunable mid-far infrared laser with high beam quality. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 The structure diagram of the dual-wavelength tunable all-solid-state mid-far infrared laser according to the embodiment of the present disclosure is schematically shown;

[0021] Figure 2 The structure diagram of the dual-wavelength tunable all-solid-state mid-far infrared laser when the gain modulation device is configured as an electro-optic Q-switching element according to the embodiment of the present disclosure is schematically shown;

[0022] Figure 3 The output wavelength tuning curve diagram of the dual-wavelength tunable all-solid-state mid-far infrared laser according to the embodiment of the present disclosure is schematically shown;

[0023] Figure 4 The structure diagram of the dual-wavelength tunable all-solid-state mid-far infrared laser according to another embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It is to be understood, however, that the description is merely exemplary of the present disclosure, and is intended to provide a thorough description for implementations of the present disclosure, and merely to convey the substance of the present disclosure. In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring the concepts of the present disclosure.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the term "includes" and tautological expressions thereof, such as "including," "includes," "include," "contains," "containing," and so forth, shall be read expansively and without limitation. The terms "comprising," "including," and "having," and tautological expressions thereof (e.g., "comprises essentially," "has at least essentially") are inclusive using the definition applied to each term by those skilled in the art; the use of these terms and tautological expressions shall not be read into the construction of the present disclosure.

[0026] All terms used herein including technical and scientific terms have the same meanings as commonly understood by those skilled in the art unless otherwise defined herein. It should be noted that the terms used herein are merely specific ones and should not be interpreted as limiting the present disclosure.

[0027] In the case of using expressions similar to "at least one of A, B, and C," it is generally to be understood that the expression is intended to convey the meaning of "at least one of A, at least one of B, and at least one of C" (e.g., the system "having at least one of A, B, and C" would include but not be limited to a system having at least A alone, at least B alone, at least C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C, etc.).

[0028] 3 μm near band laser, 3-5 μm mid-wave infrared laser and 8-12 μm long-wave infrared laser are all in the atmospheric transmission window, and have a relatively broad application prospect in the fields of laser radar, spectroscopy, atmospheric environment detection, scientific research and photoelectric countermeasure, etc. Remote sensing of toxic and harmful gases in the atmosphere is an important part of environmental quality monitoring. The mid-wave infrared and long-wave infrared bands both cover the characteristic absorption peaks of a variety of toxic gases, and the laser in this band is usually used for toxic gas detection. The differential absorption laser radar (DIAL) system developed based on the differential absorption spectroscopy technology has the characteristics of active detection, long working distance, high detection precision, etc., and has been widely used in the measurement and monitoring of a variety of toxic gases. The DIAL usually uses a tunable laser as a light source, and needs to continuously emit two laser pulses of different wavelengths during measurement, which puts forward higher requirements for the tuning range and tuning speed of the laser. The dual-wavelength tunable mid-infrared and far-infrared laser can simultaneously output two wavelengths of mid-wave infrared laser and two wavelengths of long-wave infrared laser, and has great significance for improving the detection precision and sensitivity of multi-component toxic gases.

[0029] In recent years, laser beams with simultaneous output of middle and long waves have wide application value in the fields of laser target indication and photoelectric countermeasure. Photons with a wavelength of 3 μm can be converted into long-wave infrared idler light with a wavelength of 8-12 μm and middle-wave infrared signal light with a wavelength of 4.8-4.0 μm through nonlinear frequency conversion technology. Therefore, dual-wavelength 3 μm band laser with high beam quality is the basis for obtaining dual-wavelength tunable middle and long wave laser beams, in addition, the 3 μm band laser is also near the water absorption band and is a commonly used medical light source. However, the related technology for obtaining high-performance dual-wavelength 3 μm band laser and its pumped middle and far infrared laser is still in a blank state.

[0030] LD (Laser Diode-laser diode) direct pumped erbium-doped laser is an effective means to obtain 3 μm band laser, which has the advantages of compact structure, high gain and high efficiency.

[0031] Based on this, the embodiment of the disclosure provides a dual-wavelength tunable all-solid-state middle and far infrared laser, comprising: an erbium-doped laser and an optical parametric oscillator.

[0032] The erbium-doped laser is used to provide dual-wavelength 3 μm band pulsed laser to pump the optical parametric oscillator.

[0033] The erbium-doped laser specifically comprises: a pump source, an erbium-doped laser medium, a gain modulation device, a high-reflectivity mirror and an output mirror.

[0034] The pump source is used to provide pump light; the erbium-doped laser medium comprises a first laser medium and a second laser medium, and is used to generate dual-wavelength 3 μm band laser under the pumping action of the pump light; the gain modulation device is used to obtain dual-wavelength 3 μm band pulsed laser by adjusting the loss state of the resonant cavity; the high-reflectivity mirror is used to reflect the dual-wavelength 3 μm band pulsed laser; and the output mirror and the high-reflectivity mirror together form a resonant cavity, and are used to output the dual-wavelength 3 μm band pulsed laser.

[0035] The optical parametric oscillator is used to obtain dual-wavelength middle-wave infrared laser and dual-wavelength long-wave infrared laser under the pumping action of the dual-wavelength 3 μm band pulsed laser.

[0036] The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiments of the present disclosure adopts two kinds of erbium-doped laser mediums, combines gain modulation technology, realizes the output of dual-wavelength 3 μm band pulse laser, then adopts the dual-wavelength 3 μm band pulse laser to pump a nonlinear crystal, and based on single-resonant optical parametric oscillation technology, realizes tunable dual-wavelength laser in the mid-long wave infrared band with good beam quality. The mid-far infrared laser has simple structure and is convenient to use, can obtain tunable dual-wavelength mid-far infrared laser with high beam quality, and meets the light source demand of differential absorption laser radar remote sensing of toxic gas and photoelectric countermeasure.

[0037] In order to make the objects, technical solutions and advantages of the present disclosure clearer, further detailed description will be made to the present disclosure in combination with specific embodiments and with reference to the drawings.

[0038] Figure 1 The structure diagram of the dual-wavelength tunable all-solid-state mid-far infrared laser according to the embodiments of the present disclosure is schematically shown.

[0039] As shown in Figure 1 , the dual-wavelength tunable all-solid-state mid-far infrared laser of the embodiments of the present disclosure may, for example, include an erbium-doped laser and an optical parametric oscillator.

[0040] The erbium-doped laser is used to provide pulse laser in the dual-wavelength 3 μm band to pump the optical parametric oscillator.

[0041] The erbium-doped laser specifically includes a pump source, an erbium-doped laser medium, a gain modulation device, a high reflection mirror M1 and an output mirror M2.

[0042] The pump source is used to provide pump light.

[0043] In the present embodiment, the pump source may adopt a semiconductor laser. Er 3+ ions have absorption peaks near wavelengths of 650 nm, 795 nm, 976 nm and the like in the visible-near infrared region. Compared with the other two, 976 nm pumping has higher quantum efficiency, and can directly excite ground state particles to upper energy levels (4I13 / 2 4 I 11 / 2 ), reducing the heat generated by other processes. Therefore, the center wavelength of the semiconductor laser in the present embodiment is preferably 976 nm.

[0044] The erbium-doped laser medium includes a first laser medium and a second laser medium, and is used to generate dual-wavelength 3 μm band laser under the pumping action of pump light.

[0045] In the embodiment, the first laser medium and the second laser medium constituting the erbium-doped laser medium are both anisotropic erbium-doped laser medium, and the stimulated emission peaks thereof correspond to the double-wavelength specified waveband. Specifically, the erbium-doped laser medium can be an erbium-doped crystal with different doping concentrations and substrates, or a laser crystal, a glass, a ceramic, a fiber, a dye, a titanium sapphire, or the like doped with rare earth ions.

[0046] The gain modulation device is used to obtain the double-wavelength specified waveband pulsed laser by adjusting the loss state of the resonant cavity.

[0047] In the embodiment, the gain modulation device can be configured as an electro-optic Q-switching device, as shown in Figure 2 .

[0048] Figure 2 A structure diagram of the double-wavelength tunable all-solid-state mid-infrared laser when the gain modulation device according to the embodiment of the present disclosure is configured as an electro-optic Q-switching element is schematically shown.

[0049] As shown in Figure 2 , the electro-optic Q-switching device can specifically include a first polarizer M4, a quarter-wave plate M5, and a Q-switch.

[0050] The first polarizer M4 is used to determine the polarization state of the double-wavelength 3 μm waveband laser, which can be composed of 1-3 pieces of Al2O3 flakes, for example. The quarter-wave plate M5 is used to adjust the polarization direction of the double-wavelength 3 μm waveband laser, so that the double-wavelength 3 μm waveband laser can pass through the first polarizer M4 in a determined polarization state. The Q-switch is used to obtain the double-wavelength 3 μm waveband pulsed laser by adjusting the loss state of the resonant cavity.

[0051] In the embodiment, the electro-optic Q-switching technology is adopted, and the Q-switch is configured as an electro-optic Q-switch, wherein the Q crystal in the electro-optic Q-switch can be a lanthanum gallium silicate crystal (LGS), a lithium niobate crystal (LN), or other electro-optic crystals that can be used in the waveband near 3 μm. By using the electro-optic effect of the crystal, when no quarter-wave voltage is applied to the Q crystal, the polarization state of the p-polarized laser changes to s-polarization after passing through the quarter-wave plate and the Q crystal twice, and the laser cannot pass through the first polarizer, the loss in the resonant cavity is large, and the laser cannot oscillate; when the population of the energy level particles on the gain medium accumulates to the maximum, the Q crystal is applied with a quarter-wave voltage, the loss in the cavity is reduced, the laser outputs a giant pulse, and the double-wavelength pulsed laser output with high peak power is obtained.

[0052] It should be noted that the gain modulation device can be configured as an acousto-optic Q-switching element or a passive Q-switching medium in addition to being configured as an electro-optic Q-switching element, and is not limited to a saturable absorber crystal, but can be any Q-switching working substance that has a certain degree of absorption to the laser wavelength emitted by the laser working substance. The present embodiment is not limited in this regard.

[0053] The high reflector M1 is used for reflecting the dual-wavelength 3 μm band pulsed laser.

[0054] The output mirror M2 forms a resonant cavity together with the high reflector M1, and is used for outputting the dual-wavelength 3 μm band pulsed laser.

[0055] The optical parametric oscillator is used for obtaining dual-wavelength mid-wave infrared laser and dual-wavelength long-wave infrared laser under the pumping action of the dual-wavelength 3 μm band pulsed laser.

[0056] In the present embodiment, the optical parametric oscillator adopts a straight cavity structure, and realizes dual-wavelength tunable mid-far infrared laser with good beam quality through single resonance of signal light or idler light.

[0057] It should be noted that the optical parametric oscillator can adopt a straight cavity structure, and can also adopt a V-shaped cavity, a four-cavity mirror ring cavity, or a rotating image single-resonance twisted rectangular (RISTRA) cavity, and the like. The present embodiment is not limited in this regard.

[0058] The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the present disclosure adopts two kinds of erbium-doped laser media, and combines electro-optic Q-switching technology to realize the output of dual-wavelength 3 μm band pulsed laser. Then, the dual-wavelength 3 μm band pulsed laser is used to pump a nonlinear crystal, and based on single-resonance optical parametric oscillation technology, tunable dual-wavelength laser in the mid-long-wave infrared band with good beam quality is realized. The mid-far infrared laser has a simple structure and is easy to use, and can obtain tunable dual-wavelength mid-far infrared laser with high beam quality, thereby meeting the light source requirements of differential absorption laser radar remote sensing of toxic gases and photoelectric countermeasures.

[0059] According to the present disclosure, the LD pump source can be configured as a double-end pump structure, and a U-shaped double-concave resonant cavity composed of the high reflector M1 and the output mirror M2. The double-end pump structure specifically includes:

[0060] The first pump source is arranged at one end close to the first laser medium, and is used for pumping the first laser medium. The output spectral line of the first pump source matches the absorption spectral line of the first laser medium.

[0061] The second pump source is arranged at one end close to the second laser medium, and is used for pumping the second laser medium. The output spectral line of the second pump source matches the absorption spectral line of the second laser medium.

[0062] In the embodiment, the light beam shaping module is arranged behind the first pump source and the second pump source, so that the waists of the pump light spots of the two pump sources are located at the centers of the first laser medium and the second laser medium respectively. By adjusting the pump power of the double-end pump structure, the laser power ratio of the dual-wavelength 3-micron-band pulsed laser can be adjusted.

[0063] The dual-wavelength tunable all-solid-state mid-far infrared laser provided by the embodiment of the present disclosure adopts a double-end pump structure, pumps an erbium-doped laser medium by two pump sources, and can realize continuous adjustment of the output power / energy ratio of the dual-wavelength laser by directly controlling the pump power of the two pump sources.

[0064] In the embodiment, the first laser medium and the second laser medium can be Er:YAP crystals and Er:YLF crystals respectively. The YAP crystal and the YLF crystal are both negative biaxial crystals, have good thermal conductivity and low phonon energy, have good absorption characteristics at 976 nm, and are easier to obtain high-efficiency laser oscillation. After the erbium-doped laser medium is pumped by light of the corresponding wavelength, 3-micron-band and near-wavelength laser can be output. The erbium-doped laser medium is bonded by the first laser medium and the second laser medium, which can improve the uniformity of the crystal in the heating process and help to weaken the thermal lens effect. The erbium ion doping concentration of the first laser medium is 5%, which is used to generate 2.78-micron pulsed laser; and the erbium ion doping concentration of the second laser medium is 6%, which is used to generate 2.67-micron pulsed laser.

[0065] It should be noted that the first laser medium and the second laser medium can be other single-doped or co-doped laser crystals, glasses, ceramics, optical fibers, dyes, titanium sapphire, etc. The erbium-doped laser medium can be composed of the first laser medium and the second laser medium, or can be composed of discrete or bonded laser media, and the embodiment does not limit this.

[0066] According to the embodiment of the present disclosure, the optical parametric oscillator comprises a first nonlinear crystal, an input cavity mirror M6 and an output cavity mirror M7.

[0067] The first nonlinear crystal is used to realize frequency nonlinear transformation of the dual-wavelength 3-micron-band pulsed laser.

[0068] The input cavity mirror M6 is arranged at the input end of the first nonlinear crystal and is used to input the dual-wavelength 3-micron-band pulsed laser.

[0069] The output cavity mirror M7 is arranged at the output end of the first nonlinear crystal and forms an optical parametric oscillation resonant cavity together with the input cavity mirror M6, and is used to output the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser.

[0070] In the embodiment, the first nonlinear crystal can be a zinc germanium phosphide (ZGP) crystal or a barium gallium selenide (BGSe) crystal. The ZGP crystal has a high nonlinear coefficient (75 pm / V) and a high thermal conductivity (0.36 W / cm·K), and a moderate damage threshold (86 MW / cm 2 @2.09 μm, 21 ns, 1 kHz), so that it has a great advantage in the optical parametric oscillation process. However, due to the reduction of transmittance and the influence of two-photon absorption, the conversion efficiency of the crystal is low for OPO above 10 μm. The BGSe crystal has a moderate nonlinear coefficient (31.5 pm / V) and a high damage threshold (557 MW / cm 2 @1.06 μm, 5 ns, 1 Hz), and the light transmission range reaches 0.47-18 μm. By using the ZGP or BGSe crystal, a high-performance dual-wavelength mid-infrared laser can be realized.

[0071] It should be noted that the first nonlinear crystal can be a zinc germanium phosphide (ZGP) crystal or a barium gallium selenide (BGSe) crystal, and can also be other mid-infrared nonlinear crystals, including oxide crystals and non-oxide crystals, such as silver gallium sulfide (AGS), silver gallium selenide (AGSe), gallium selenide (GaSe), chromium selenide (CdSe), mercury gallium sulfide (HGS), etc. The present embodiment is not limited thereto.

[0072] In the embodiment, the input mirror M6 is coated with HT@2.6-3.0 μm and HR@3.6-4.8 μm or HR@8.0-10.0 μm. The output mirror M7 is coated with HT@2.6-3.0 μm, 8.0-10.0 μm and PR@3.6-4.8 μm or HT@2.6-3.0 μm, 3.6-4.8 μm and PR@8.0-10.0 μm.

[0073] In the embodiment, the input mirror M6 and the output mirror M7 are slightly inclined, so that a small amount of reflected pump light can avoid affecting the stable operation of the erbium-doped laser.

[0074] According to the embodiment of the present disclosure, the dual-wavelength tunable all-solid-state mid-infrared laser further comprises a beam splitter M3, specifically comprising a first beam splitter M31 and a second beam splitter M32 arranged in the erbium-doped laser.

[0075] The first beam splitter M31 is arranged between the first pump source and the first laser medium, and is used to transmit the pump light provided by the first pump source and reflect the dual-wavelength 3 μm band laser generated by the erbium-doped laser medium.

[0076] The second beam splitter M32 is disposed between the second pump source and the second laser medium, and is used to transmit the pump light provided by the second pump source and reflect the dual-wavelength 3 μm band laser generated by the erbium-doped laser medium.

[0077] According to an embodiment of the present disclosure, the dual-wavelength tunable all-solid-state mid- and far-infrared laser further includes: a third beam splitter M33, a fourth beam splitter M8, and a fifth beam splitter M9 disposed outside the erbium-doped laser.

[0078] The third beam splitter M33 is provided between the output mirror M2 and the input cavity mirror M6, and is used to reflect the dual-wavelength 3 μm-band pulsed laser generated by the erbium-doped laser to the first nonlinear crystal. Preferably, a beam shaping module is also provided after the third beam splitter M33.

[0079] The fourth beam splitter M8 is provided at one end of the output cavity mirror M7 and is used to reflect the remaining dual-wavelength 3 μm band pulse laser after passing through the first nonlinear crystal, as well as the dual-wavelength medium-wave infrared laser and dual-wavelength long-wave infrared laser generated by the transmitted optical parametric oscillator.

[0080] The fifth beam splitter M9 is disposed at one end of the fourth beam splitter M8 and is configured to reflect the dual-wavelength medium-wave infrared laser and transmit the dual-wavelength long-wave infrared laser.

[0081] To make the embodiments of the present disclosure clearer, refer to Figure 1 The dual-wavelength tunable all-solid-state mid- and far-infrared laser shown in Figure 1 In the figure, the dotted line represents the first wavelength pump light output by the pump source, which is a laser with a wavelength of 976 nm in the embodiment of the present disclosure, and is the pump light used to pump the erbium-doped laser medium; the solid line represents the second wavelength pump light, which is a dual-wavelength laser near the 3 μm band in the embodiment of the present disclosure, and is the pump light used to pump the first nonlinear crystal; the dotted line represents the third wavelength laser, which is a dual-wavelength medium-wave infrared laser in the embodiment of the present disclosure; the long dash line represents the fourth wavelength laser, which is a dual-wavelength long-wave infrared laser in the embodiment of the present disclosure.

[0082] According to the embodiments of the present disclosure, the dual-wavelength tunable all-solid-state mid-to-far infrared laser uses angle or temperature tuning to achieve tunable output of mid-to-long-wave infrared laser. Taking ZGP crystal as an example, under the pumping of dual-wavelength erbium-doped laser, the angle tuning curve is as follows: Figure 3 shown.

[0083] Figure 3 The output wavelength tuning curve of the dual-wavelength tunable all-solid-state mid- and far-infrared laser according to an embodiment of the present disclosure is schematically shown.

[0084] like Figure 3As shown, the pump light wavelength is taken as 2.67 μm and 2.78 μm. When the phase matching angle of the ZGP crystal is 48.0° (θ=48.0°, φ=90°), the long-wave infrared laser of 7.86 μm and 8.03 μm and the mid-wave infrared laser of 4.04 μm and 4.25 μm are obtained, and the wavelength interval is 0.17 μm and 0.21 μm, respectively; when the phase matching angle of the ZGP crystal is 49.6° (θ=49.6°, φ=90°), the long-wave infrared laser of 10.05 μm and 9.88 μm and the mid-wave infrared laser of 3.63 μm and 3.87 μm are obtained, and the wavelength interval is -0.17 μm and 0.24 μm, respectively. A wide tuning range and wavelength interval can be achieved in the mid-long-wave infrared band.

[0085] Figure 4 A structural diagram of a dual-wavelength tunable all-solid-state mid-far infrared laser according to another embodiment of the present disclosure is schematically shown.

[0086] As shown, the dual-wavelength tunable all-solid-state mid-far infrared laser of another embodiment of the present disclosure further comprises an optical parametric amplifier and an adjustable attenuator. Figure 4

[0087] The optical parametric amplifier is arranged at the output end of the optical parametric oscillator, and is used for amplifying the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator.

[0088] The adjustable attenuator is arranged at the output end of the erbium-doped laser, and is used for adjusting the laser power of the dual-wavelength 3 μm band pulse laser injected into the optical parametric oscillator and the optical parametric amplifier.

[0089] The adjustable attenuator can specifically comprise a first half-wave plate M10 and a second polarizer M11.

[0090] The first half-wave plate M10 is used for adjusting the polarization direction of the dual-wavelength 3 μm band laser, and the second polarizer M11 divides the dual-wavelength 3 μm band pulse laser into two paths, one of which is used for pumping the optical parametric oscillator, and the other of which is used for pumping the optical parametric amplifier.

[0091] The optical parametric amplifier can specifically comprise a beam combiner M12 and a second nonlinear crystal.

[0092] The beam combiner M12 is arranged at the output end of the optical parametric oscillator, and is used for combining the dual-wavelength 3 μm band pulse laser and the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator.

[0093] ​The second nonlinear crystal is used for amplifying the dual-wavelength mid-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator under the pumping of the dual-wavelength 3-micron band pulsed laser after beam combination.

[0094] In the embodiment, the second nonlinear crystal can also be a zinc germanium phosphide (ZGP) crystal or a barium gallium selenide (BGSe) crystal. After beam shaping, the erbium-doped laser is divided into two paths by the adjustable attenuator composed of the first half-wave plate M10 and the second polarizer M11, one path directly pumps the optical parametric oscillator to realize generation of the dual-wavelength mid-infrared laser, and the other path, after passing through the mirror M13 and the second half-wave plate M14, matches the polarization state of the dual-wavelength mid-infrared seed laser, pumps the second nonlinear crystal to realize amplification of the dual-wavelength mid-infrared laser.

[0095] The dual-wavelength tunable all-solid-state mid-infrared laser provided by the embodiment of the present disclosure adopts the cascaded pumping mode of "LD pump source→erbium-doped laser→optical parametric oscillator→optical parametric amplifier", ensures a relatively high mode matching factor of the resonant cavity, and obtains a dual-wavelength tunable mid-infrared laser with a relatively high beam quality.

[0096] It should be noted that the optical parametric amplifier is not only applicable to the erbium-doped laser provided by the embodiment of the present disclosure, but also applicable to other erbium-doped lasers outside the embodiment of the present disclosure, that is, the optical parametric amplifier can be cascaded with the erbium-doped laser provided by the embodiment of the present disclosure, or can be cascaded with other erbium-doped lasers outside the embodiment of the present disclosure, and the present disclosure does not limit this.

[0097] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of the systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or part of the code, which contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the boxes can also occur in an order different from that marked in the accompanying drawings. For example, two boxes shown in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, as well as the combination of boxes in the block diagram or flowchart, can be implemented using a dedicated hardware-based system that performs the specified functions or operations, or can be implemented using a combination of dedicated hardware and computer instructions. It will be understood by those skilled in the art that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways, and all of these combinations and / or couplings fall within the scope of the present disclosure.

[0098] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A dual-wavelength tunable all-solid-state mid- and far-infrared laser, characterized in that: include: An erbium-doped laser is used to provide pulsed laser light in a dual-wavelength specified band, wherein the erbium-doped laser comprises: A pump source, used to provide pump light; The erbium-doped laser medium comprises a first laser medium and a second laser medium, and is used to generate a dual-wavelength laser of a specified wavelength band under the pumping action of the pump light; A gain modulation device is used to obtain a dual-wavelength pulsed laser in a specified wavelength band by adjusting the loss state of the resonant cavity; A highly reflective mirror, used for reflecting the dual-wavelength pulse laser of a specified wavelength band; An output mirror, which forms the resonant cavity together with the high-reflection mirror, and is used to output the dual-wavelength specified band pulse laser; An optical parametric oscillator is used to generate a dual-wavelength medium-wave infrared laser and a dual-wavelength long-wave infrared laser under the pumping action of the dual-wavelength specified band pulse laser; The pump source is configured as a double-ended pump structure, comprising: a first pump source, disposed near one end of the first laser medium, for pumping the first laser medium, wherein an output spectrum line of the first pump source matches an absorption spectrum line of the first laser medium; a second pump source, disposed near one end of the second laser medium, for pumping the second laser medium, wherein an output spectrum line of the second pump source matches an absorption spectrum line of the second laser medium; The laser output power ratio of the dual-wavelength specified wavelength band pulse laser can be adjusted by adjusting the pump power of the double-ended pump structure; The optical parametric oscillator comprises: A first nonlinear crystal is used to realize the frequency nonlinear conversion of the dual-wavelength specified wavelength band pulse laser; An input cavity mirror, provided at the input end of the first nonlinear crystal, for inputting the dual-wavelength specified band pulse laser; an output cavity mirror, provided at the output end of the first nonlinear crystal, and forming together with the input cavity mirror an optical parametric oscillator resonant cavity for outputting the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser; The dual-wavelength tunable all-solid-state mid- and far-infrared laser further comprises: a first beam splitter, disposed between the first pump source and the first laser medium, for transmitting the pump light provided by the first pump source and reflecting the dual-wavelength designated band laser light generated by the erbium-doped laser medium; a second beam splitter, disposed between the second pump source and the second laser medium, for transmitting the pump light provided by the second pump source and reflecting the dual-wavelength designated band laser light generated by the erbium-doped laser medium; A third beam splitter is provided between the output mirror and the input cavity mirror, and is used to reflect the dual-wavelength designated band pulse laser generated by the erbium-doped laser to the first nonlinear crystal; a fourth beam splitter, provided at one end of the output cavity mirror, for reflecting the dual-wavelength pulsed laser light of a specified wavelength band remaining after passing through the first nonlinear crystal, and transmitting the dual-wavelength medium-wave infrared laser light and the dual-wavelength long-wave infrared laser light generated by the optical parametric oscillator; The fifth beam splitter is provided at one end of the fourth beam splitter and is used for reflecting the dual-wavelength medium-wave infrared laser and transmitting the dual-wavelength long-wave infrared laser.

2. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 1, characterized in that: The first laser medium and the second laser medium are both anisotropic erbium-doped laser media, and their stimulated emission peaks correspond to dual-wavelength designated bands respectively.

3. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 1, characterized in that: The gain modulation device is configured as any one of an electro-optical Q-switching element, an acousto-optical Q-switching element, or a passive Q-switching medium; Wherein, the electro-optical Q-switched element comprises: A first polarizer, used to determine the polarization state of the dual-wavelength specified wavelength band laser; a quarter-wave plate, configured to adjust the polarization direction of the dual-wavelength specified wavelength band laser so that the dual-wavelength specified wavelength band laser can pass through the first polarizer in a determined polarization state; The electro-optic Q switch is used to obtain dual-wavelength pulsed lasers in a specified wavelength band by adjusting the loss state of the resonant cavity.

4. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 1, characterized in that: Also includes: The optical parametric amplifier is provided at the output end of the optical parametric oscillator and is used for amplifying the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator.

5. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 4, characterized in that: Also includes: An adjustable attenuator is provided at the output end of the erbium-doped laser and is used to adjust the laser power of the dual-wavelength specified-band pulse laser injected into the optical parametric oscillator and the optical parametric amplifier, comprising: A first half-wave plate, used for adjusting the polarization direction of the dual-wavelength specified wavelength band laser; The second polarizer divides the dual-wavelength designated band pulse laser into two paths, one of which is used to pump the optical parametric oscillator, and the other is used to pump the optical parametric amplifier.

6. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 5, characterized in that: The optical parametric amplifier comprises: a beam combining mirror, provided at the output end of the optical parametric oscillator, for combining the dual-wavelength specified-band pulse laser with the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator; The second nonlinear crystal is used to amplify the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator under the pumping action of the combined dual-wavelength specified-band pulse laser.

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