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

Abstract

The invention provides a dual-wavelength tunable all-solid-state mid-far infrared laser, relates to the technical field of lasers, and is used for solving the technical problems that high-performance dual-wavelength 3 [mu] m waveband laser and mid-far infrared waveband laser generated by pumping of the high-performance dual-wavelength 3 [mu] m waveband laser are difficult to obtain in the prior art. The middle and far infrared laser comprises an erbium-doped laser and an optical parametric oscillator, the erbium-doped laser is used for providing dual-wavelength 3-micron wave band pulse laser, and the erbium-doped laser comprises a pumping source, an erbium-doped laser medium, a gain modulator, a high reflective mirror and an output mirror; the optical parametric oscillator is used for obtaining medium-wave infrared laser and long-wave infrared laser which are output in a dual-wavelength mode under the pumping effect of the dual-wavelength pulse laser in the 3-micron wave band. The mid-far infrared laser is simple in structure and convenient to use, can obtain tunable dual-wavelength mid-far infrared pulse laser with high beam quality, and meets the light source requirements of differential absorption of toxic gas telemetering of laser radar and photoelectric countermeasure.

Description

Technical Field

[0001] The present disclosure relates to the field of laser technology, and more specifically, to a dual-wavelength tunable all-solid-state mid- and far-infrared laser. Background Art

[0002] Lasers in the 3 μm band, 3-5 μm mid-wave infrared lasers, and 8-12 μm long-wave infrared lasers are all in the atmospheric transmission window, and have broad application prospects in the fields of laser radar, spectroscopy, atmospheric environment detection, scientific research, and optoelectronic countermeasures. Remote sensing of toxic and harmful gases in the atmosphere is an important part of environmental quality monitoring. Among them, both the mid-wave infrared and long-wave infrared bands cover the characteristic absorption peaks of a variety of toxic gases, and lasers in this band are usually used for toxic gas detection. The differential absorption laser radar (DIAL) system developed based on differential absorption spectroscopy technology has the characteristics of active detection, long working distance, and high detection accuracy, and has been widely used in the measurement and monitoring of a variety of toxic gases. DIAL usually uses a tunable laser as a light source. During measurement, it is necessary to continuously emit two laser pulses of different wavelengths, which puts forward high requirements on the tuning range and tuning speed of the laser. The dual-wavelength tunable mid- and far-infrared laser can simultaneously output two wavelengths of mid-wave infrared lasers and two wavelengths of long-wave infrared lasers, which is of great significance to improving the detection accuracy and sensitivity of multi-component toxic gases.

[0003] In recent years, medium- and long-wave laser beams have been widely used in the fields of laser target indication and optoelectronic countermeasures. Photons with a wavelength of 3 μm can be converted into long-wave infrared idler light with a wavelength of 8-12 μm and medium-wave infrared signal light with a wavelength of 4.8-4.0 μm through nonlinear frequency conversion technology. Therefore, dual-wavelength lasers with high beam quality near 3 μm are the basis for obtaining dual-wavelength tunable medium- and long-wave laser beams. In addition, lasers in the band near 3 μm are also located near the absorption band of water and are commonly used medical light sources. However, the relevant technologies for obtaining high-performance dual-wavelength 3 μm band lasers and their pumped medium- and far-infrared lasers are always vacant. Summary of the invention

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

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

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

[0007] According to an embodiment of the present disclosure, a pump source is configured as a double-ended pumping structure, including: a first pumping source, disposed at one end close to a first laser medium, for pumping the first laser medium, wherein an output spectrum line of the first pumping source matches an absorption spectrum line of the first laser medium; a second pumping source, disposed at one end close to a second laser medium, for pumping the second laser medium, wherein an output spectrum line of the second pumping source matches an absorption spectrum line of the second laser medium; wherein by adjusting the pumping power of the double-ended 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-optical Q-switching element, an acousto-optical Q-switching element or a passive Q-switching medium; wherein the electro-optical Q-switching element includes: a first polarizer, used to determine the polarization state of the dual-wavelength designated band laser; a quarter-wave plate, used to adjust the polarization direction of the dual-wavelength designated band laser so that the dual-wavelength designated band laser can pass through the first polarizer in a determined polarization state; an electro-optical Q switch, used to obtain a dual-wavelength designated 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 includes: a first nonlinear crystal, used to realize the frequency nonlinear conversion of a dual-wavelength specified band pulse laser; an input cavity mirror, arranged at the input end of the first nonlinear crystal, used to input a dual-wavelength specified band pulse laser; an output cavity mirror, arranged at the output end of the first nonlinear crystal, and forming an optical parametric oscillator resonant cavity together with the input cavity mirror, used to output a dual-wavelength medium-wave infrared laser and a dual-wavelength long-wave infrared laser.

[0010] According to an embodiment of the present disclosure, it also includes: a first spectroscope, which 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 designated band laser generated by the erbium-doped laser medium; a second spectroscope, which is arranged 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 designated band laser generated by the erbium-doped laser medium.

[0011] According to an embodiment of the present disclosure, it also includes: a third beam splitter, arranged between the output mirror and the input cavity mirror, and used to reflect the dual-wavelength specified band pulse laser generated by the erbium-doped laser to the first nonlinear crystal; a fourth beam splitter, arranged at one end of the output cavity mirror, and used to reflect the dual-wavelength specified band pulse laser remaining after passing through the first nonlinear crystal, and the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the transmitted optical parametric oscillator; a fifth beam splitter, arranged at one end of the fourth beam splitter, and used to reflect the dual-wavelength medium-wave infrared laser, and transmit the dual-wavelength long-wave infrared laser.

[0012] According to an embodiment of the present disclosure, it also includes: an optical parametric amplifier, which is arranged at the output end of the optical parametric oscillator and 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.

[0013] According to an embodiment of the present disclosure, it also includes: an adjustable attenuator, which is arranged 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, including: a first half-wave plate, which is used to adjust the polarization direction of the dual-wavelength specified band laser; a second polarizer, which divides the dual-wavelength specified 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.

[0014] According to an embodiment of the present disclosure, the optical parametric amplifier includes: a beam combining mirror, which is arranged at the output end of the optical parametric oscillator, and is used to combine the dual-wavelength specified band pulse laser and the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator; a second nonlinear crystal, which 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 dual-wavelength specified band pulse laser after beam combining.

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

[0016] (1) The dual-wavelength tunable all-solid-state mid-to-far infrared laser provided in the embodiment of the present disclosure adopts two erbium-doped laser media and combines gain modulation 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 nonlinear crystals. Based on the single resonant optical parametric oscillation technology, a tunable dual-wavelength laser with good beam quality in the mid-to-long-wave infrared band is realized. The mid-to-far infrared laser has a simple structure and is easy to use. It can obtain a tunable dual-wavelength mid-to-far infrared laser with high beam quality, which meets the light source requirements of differential absorption laser radar remote sensing of toxic gases and optoelectronic countermeasures.

[0017] (2) The dual-wavelength tunable all-solid-state mid- and far-infrared laser provided in the embodiments of the present disclosure uses two pump sources to pump the erbium-doped laser medium respectively to achieve dual-wavelength laser output. By directly controlling the pump powers of the two pump sources, the dual-wavelength laser output power / energy ratio can be continuously adjusted.

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

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

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

[0021] Figure 2 A schematic diagram of the structure of a dual-wavelength tunable all-solid-state mid- and far-infrared laser when the gain modulation device according to an embodiment of the present disclosure is configured as an electro-optical Q-switched element;

[0022] Figure 3 Schematically shows an output wavelength tuning curve diagram of a dual-wavelength tunable all-solid-state mid-to-far infrared laser according to an embodiment of the present disclosure;

[0023] Figure 4 The structure of a dual-wavelength tunable all-solid-state mid- and 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. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

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

[0029] In recent years, medium- and long-wave laser beams have been widely used in the fields of laser target indication and optoelectronic countermeasures. Photons with a wavelength of 3 μm can be converted into long-wave infrared idler light with a wavelength of 8-12 μm and medium-wave infrared signal light with a wavelength of 4.8-4.0 μm through nonlinear frequency conversion technology. Therefore, high-quality dual-wavelength 3 μm band lasers are the basis for obtaining dual-wavelength tunable medium- and long-wave laser beams. In addition, lasers in the 3 μm band are also located near the absorption band of water and are commonly used medical light sources. However, the relevant technologies for obtaining high-performance dual-wavelength 3 μm band lasers and their pumped mid- and far-infrared lasers are always vacant.

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

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

[0032] The erbium-doped laser is used to provide a 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-reflection mirror and an output mirror.

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

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

[0036] The dual-wavelength tunable all-solid-state mid-to-far infrared laser provided in the embodiment of the present disclosure adopts two erbium-doped laser media and combines gain modulation technology to realize the output of dual-wavelength 3μm band pulsed laser, and then adopts the dual-wavelength 3μm band pulsed laser to pump nonlinear crystal, based on single resonant optical parametric oscillation technology, to realize tunable dual-wavelength laser in the mid-to-long wave infrared band with good beam quality. The mid-to-far infrared laser has a simple structure and is easy to use. It can obtain a tunable dual-wavelength mid-to-far infrared laser with high beam quality, which meets the light source requirements of differential absorption laser radar remote sensing of toxic gases and photoelectric countermeasures.

[0037] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

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

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

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

[0041] The erbium-doped laser specifically comprises: 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 this embodiment, the pump source may be a semiconductor laser. 3+ Ions have absorption peaks near wavelengths of 650 nm, 795 nm, and 976 nm in the visible-near infrared region. In comparison, 976 nm pumping has higher quantum efficiency and can directly excite ground-state particles to the upper energy level ( 4 I 11 / 2 ), reducing the heat generated by other processes, therefore, the central wavelength of the semiconductor laser in this embodiment is preferably 976 nm.

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

[0045] In this embodiment, the first laser medium and the second laser medium constituting the erbium-doped laser medium are both anisotropic erbium-doped laser media, and their stimulated emission peaks correspond to dual wavelength designated bands. Specifically, the erbium-doped laser medium can be erbium-doped crystals with different doping concentrations / matrixes, or laser crystals, glass, ceramics, optical fibers, dyes, titanium sapphire, etc., which are single-doped, bonded, or glued with rare earth ions.

[0046] The gain modulation device is used to obtain dual-wavelength pulsed lasers in a specified wavelength band by adjusting the loss state of the resonant cavity.

[0047] In this embodiment, the gain modulation device can be configured as an electro-optical Q-switched device, such as Figure 2 shown.

[0048] Figure 2 The structure of a dual-wavelength tunable all-solid-state mid- and far-infrared laser is schematically shown when the gain modulation device according to an embodiment of the present disclosure is configured as an electro-optical Q-switched element.

[0049] like Figure 2 As shown, the electro-optical Q-switching device may 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 dual-wavelength 3 μm band laser, and can be composed of 1-3 Al2O3 sheets, for example. The quarter-wave plate M5 is used to adjust the polarization direction of the dual-wavelength 3 μm band laser, so that the dual-wavelength 3 μm band laser can pass through the first polarizer M4 in a determined polarization state. The Q switch is used to obtain a dual-wavelength 3 μm band pulsed laser by adjusting the loss state of the resonant cavity.

[0051] In this embodiment, the electro-optical Q-switching technology is adopted, and the Q switch is configured as an electro-optical Q switch, wherein the Q crystal in the electro-optical Q switch can be a lanthanum gallium silicate crystal (LGS), a lithium niobate crystal (LN) or other electro-optical crystals that can be used in the band near 3 μm. By utilizing the electro-optical effect of the crystal, when a quarter-wave voltage is not applied to both ends of the Q crystal, after the p-polarized laser passes through the quarter-wave plate and the Q crystal twice, the laser polarization state changes to s-polarization, and it cannot pass through the first polarizer, and the loss in the resonant cavity is very large, and it cannot oscillate; when the number of energy level particles on the gain medium accumulates to the maximum, a quarter-wave voltage is applied to the Q crystal, the loss in the cavity is reduced, and the laser outputs giant pulses, and a high peak power dual-wavelength pulse laser output is obtained.

[0052] It should be noted that in addition to being configured as an electro-optical Q-switching element, the gain modulation device can also be configured as an acousto-optic Q-switching element or a passive Q-switching medium, and is not limited to saturable absorber crystals, but can also be any Q-switching working material that can absorb the laser wavelength emitted by the laser working material to a certain extent. This embodiment does not impose any restrictions on this.

[0053] The high-reflection mirror M1 is used to reflect the dual-wavelength 3 μm band pulse laser.

[0054] The output mirror M2 and the high-reflection mirror M1 together form a resonant cavity for outputting dual-wavelength 3 μm band pulsed laser.

[0055] The optical parametric oscillator is used to obtain dual-wavelength medium-wave infrared laser and dual-wavelength long-wave infrared laser under the pumping action of dual-wavelength 3 μm band pulse laser.

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

[0057] It should be noted that, in addition to the straight cavity structure, the optical parametric oscillator may also adopt a V-shaped cavity, a four-cavity mirror ring cavity, a rotating image single resonant twisted rectangular (RISTRA) cavity or other related cavity structures, and this embodiment does not impose any limitation on this.

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

[0059] According to an embodiment of the present disclosure, the LD pump source can be configured as a double-ended pump structure, and a U-shaped double-concave resonant cavity is formed by a high-reflection mirror M1 and an output mirror M2. The double-ended pump structure specifically includes:

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

[0062] In this embodiment, beam shaping modules are provided 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 center of the first laser medium and the second laser medium, respectively. By adjusting the pump power of the double-ended pumping structure, the laser power ratio of the dual-wavelength 3 μm band pulsed laser can be adjusted.

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

[0064] In this embodiment, the first laser medium and the second laser medium can be Er:YAP crystal and Er:YLF crystal, respectively, wherein both YAP crystal and YLF crystal are 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, it can output lasers in the 3 μm band and its nearby wavelengths. The erbium-doped laser medium is bonded by the first laser medium and the second laser medium, which can improve the heating uniformity of the crystal during the pumping process and help to reduce the thermal lens effect. Among them, the erbium ion doping concentration of the first laser medium is 5%, which is used to generate a 2.78 μm pulsed laser; the erbium ion doping concentration of the second laser medium is 6%, which is used to generate a 2.67 μm pulsed laser.

[0065] It should be noted that, in addition to Er:YAP crystal and Er:YLF crystal, the first laser medium and the second laser medium may also be other single-doped or co-doped laser crystals, glass, ceramics, optical fibers, dyes, titanium sapphire, etc. The erbium-doped laser medium may be composed of the first laser medium and the second laser medium bonded together, or may be composed of separate or glued laser media, which is not limited in this embodiment.

[0066] According to an embodiment of the present disclosure, the optical parametric oscillator includes: 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 conversion of dual-wavelength 3 μm band pulse laser.

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

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

[0070] In this embodiment, the first nonlinear crystal can be zinc germanium phosphide (ZGP) crystal or barium gallium selenide (BGSe) crystal, wherein the ZGP crystal has a relatively high nonlinear coefficient (75 pm / V) and thermal conductivity (0.36 W / cm·K), and a medium damage threshold (86 MW / cm 2 @2.09 μm, 21 ns, 1 kHz), which makes it have 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 this crystal is low for OPO above 10 μm. BGSe crystal has a moderate nonlinear coefficient (31.5 pm / V) and a high damage threshold (557 MW / cm 2 @1.06 μm, 5ns, 1 Hz), and the light transmission range is 0.47-18 μm. Using ZGP or BGSe crystals, high-performance dual-wavelength mid- and far-infrared lasers can be achieved.

[0071] It should be noted that, in addition to being a zinc germanium phosphide (ZGP) crystal or a barium gallium selenide (BGSe) crystal, the first nonlinear crystal may 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., and this embodiment does not impose any limitation on this.

[0072] In this embodiment, the input cavity 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 cavity 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 this embodiment, the input cavity mirror M6 and the output cavity mirror M7 are placed slightly tilted, which can prevent a small amount of reflected pump light from affecting the stable operation of the erbium-doped laser.

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

[0075] The first beam splitter M31 is disposed between the first pump source and the first laser medium, and is used for transmitting the pump light provided by the first pump source and reflecting 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 for transmitting the pump light provided by the second pump source and reflecting 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 disposed between the output mirror M2 and the input cavity mirror M6, and is used to reflect the dual-wavelength 3 μm band pulse laser generated by the erbium-doped laser to the first nonlinear crystal. Preferably, a beam shaping module is also disposed after the third beam splitter M33.

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

[0081] To make the embodiments of the present disclosure more clear, 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 the ZGP crystal as an example, under the pumping of the dual-wavelength erbium-doped laser, the angle tuning curve is as follows: Figure 3 shown.

[0083] Figure 3 The output wavelength tuning curve diagram 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 in the figure, the pump light wavelength is 2.67 μm and 2.78 μm. When the phase matching angle of the ZGP crystal is 48.0° (θ=48.0°, φ=90°), long-wave infrared lasers of 7.86 μm and 8.03 μm and medium-wave infrared lasers of 4.04 μm and 4.25 μm are obtained, respectively, and their wavelength intervals are 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°), long-wave infrared lasers of 10.05 μm and 9.88 μm and medium-wave infrared lasers of 3.63 μm and 3.87 μm are obtained, respectively, and their wavelength intervals are -0.17 μm and 0.24 μm, respectively. A wide tuning range and wavelength interval can be achieved in both the medium and long-wave infrared bands.

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

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

[0087] The optical parametric amplifier is arranged 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.

[0088] The adjustable attenuator is arranged at the output end of the erbium-doped laser and is used to adjust 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 may specifically include: a first half-wave plate M10 and a second polarizing plate M11.

[0090] Among them, the first half-wave plate M10 is used to adjust 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 to pump the optical parametric oscillator and the other is used to pump the optical parametric amplifier.

[0091] The optical parametric amplifier may specifically include: a beam combiner M12 and a second nonlinear crystal.

[0092] Among them, the beam combiner M12 is arranged at the output end of the optical parametric oscillator, which is used to combine the dual-wavelength 3 μm band pulse laser and the dual-wavelength medium-wave infrared laser and dual-wavelength long-wave infrared laser generated by the optical parametric oscillator.

[0093] 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 dual-wavelength 3 μm band pulse laser after beam combination.

[0094] In this 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 through an adjustable attenuator composed of a first half-wave plate M10 and a second polarizer M11. One path directly pumps the optical parametric oscillator to achieve the generation of dual-wavelength mid-infrared lasers; the other path passes through a reflector M13 and a second half-wave plate M14, matches the polarization state of the dual-wavelength mid-infrared seed laser, and pumps the second nonlinear crystal to achieve the amplification of the dual-wavelength mid-infrared lasers.

[0095] The dual-wavelength tunable all-solid-state mid- and far-infrared laser provided in the embodiment of the present disclosure adopts a cascade pumping method of "LD pump source → erbium-doped laser → optical parametric oscillator → optical parametric amplifier", which ensures a high mode matching factor of the resonant cavity while obtaining a dual-wavelength tunable mid- and far-infrared laser with a higher beam quality.

[0096] It should be noted that the optical parametric amplifier is not only applicable to the erbium-doped laser provided in the embodiment of the present disclosure, but also applicable to other erbium-doped lasers outside the embodiment of the present disclosure. That is to say, the optical parametric amplifier can be cascaded with the erbium-doped laser provided in the embodiment of the present disclosure, and can also be cascaded with other erbium-doped lasers outside the embodiment of the present disclosure. The present disclosure does not impose any restrictions on this.

[0097] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, 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 may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented 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, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0098] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of 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 a pulsed laser with a dual-wavelength specified band, wherein the erbium-doped laser comprises: A pump source, used for providing 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 designated band laser under the pumping action of the pump light; A gain modulation device, used to obtain a dual-wavelength pulse laser of a specified wavelength band by adjusting the loss state of the resonant cavity; A high-reflection mirror, used for reflecting the dual-wavelength designated-band pulse laser; An output mirror, which together with the high-reflection mirror forms the resonant cavity, and is used to output the dual-wavelength designated band pulse laser; The optical parametric oscillator is used to obtain a dual-wavelength medium-wave infrared laser and a dual-wavelength long-wave infrared laser under the pumping action of the dual-wavelength designated waveband pulse 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 2, characterized in that: The pump source is configured as a double-ended pump structure, comprising: A first pump source, disposed at one end close to 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 is disposed at one end close to the second laser medium and is used to pump the second laser medium, wherein an output spectrum line of the second pump source matches an absorption spectrum line of the second laser medium; Among them, by adjusting the pump power of the double-end pump structure, the laser output power ratio of the dual-wavelength specified waveband pulse laser can be adjusted.

4. 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-switching element comprises: A first polarizer, used to determine the polarization state of the dual-wavelength designated band laser; A quarter wave plate, used for adjusting the polarization direction of the dual-wavelength designated waveband laser so that the dual-wavelength designated waveband 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 band by adjusting the loss state of the resonant cavity.

5. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 3, characterized in that: The optical parametric oscillator comprises: A first nonlinear crystal, used to realize the frequency nonlinear conversion of the dual-wavelength specified wavelength band pulse laser; An input cavity mirror, arranged at the input end of the first nonlinear crystal, for inputting the dual-wavelength designated band pulse laser; The output cavity mirror is arranged at the output end of the first nonlinear crystal, and together with the input cavity mirror forms an optical parametric oscillator resonant cavity for outputting the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser.

6. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 5, characterized in that: Also includes: 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 generated by the erbium-doped laser medium; The second beam splitter is disposed between the second pump source and the second laser medium, and is used for transmitting the pump light provided by the second pump source and reflecting the dual-wavelength designated band laser generated by the erbium-doped laser medium.

7. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 6, characterized in that: Also includes: A third beam splitter is disposed 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, disposed at one end of the output cavity mirror, for reflecting the remaining dual-wavelength designated band pulse laser after passing through the first nonlinear crystal, and transmitting the dual-wavelength medium-wave infrared laser and the dual-wavelength long-wave infrared laser generated by the optical parametric oscillator; The fifth beam splitter is disposed 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.

8. 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 arranged 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.

9. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 8, 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 designated-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 designated waveband 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.

10. The dual-wavelength tunable all-solid-state mid- and far-infrared laser according to claim 9, 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 designated 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 dual-wavelength designated-band pulse laser after beam combination.

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