Tunable dual-wavelength laser generating device and method for medium-wave infrared band and long-wave infrared band

Abstract

The invention provides a medium-wave infrared and long-wave infrared band tunable dual-wavelength laser generation device and method, which are applied to the technical fields of medium-infrared laser generation, multiband photoelectric countermeasure, multi-component gas monitoring and the like. The device comprises an input mirror used for transmitting linear polarization pulse pump light of a first wavelength generated by a laser to a medium-wave infrared nonlinear crystal, wherein the medium-wave infrared nonlinear crystal is excited by the linear polarization pulse pump light to generate first-order signal light of a second wavelength and medium-wave infrared laser of a third wavelength; the medium-wave infrared output mirror is used for reflecting the first-order signal light to the total reflection mirror and transmitting and outputting medium-wave infrared laser; the total reflection mirror is used for reflecting the first-order signal light to the long-wave infrared nonlinear crystal, and the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate second-order signal light with a fourth wavelength and long-wave infrared laser with a fifth wavelength; and the long-wave infrared output mirror is used for reflecting the second-order signal light to the input mirror and transmitting and outputting long-wave infrared laser.

Description

Technical Field

[0001] The present disclosure relates to technical fields such as mid-infrared laser generation, multi-band photoelectric countermeasures, and multi-component gas monitoring, and in particular to a tunable dual-wavelength laser generation device and method based on mid-wave infrared and long-wave infrared bands. Background Art

[0002] The mid-infrared band usually refers to electromagnetic waves with wavelengths in the range of 2.5-25μm, of which the 3-5μm band is also called the mid-wave infrared band, and the 8-12μm band is also called the long-wave infrared band. Mid-wave infrared and long-wave infrared lasers have high penetration characteristics and fingerprint spectrum characteristics. Tunable mid-wave infrared and long-wave infrared laser sources have broad application prospects and value in the fields of optoelectronic countermeasures, environmental monitoring, and spectral detection. Compared with single-wavelength lasers, the application of dual-wavelength mid-infrared lasers is more distinctive. The use of dual-wavelength mid-infrared lasers can realize applications such as simultaneous monitoring of multi-component gases, broadband multi-component spectral detection, and multi-band optoelectronic countermeasures.

[0003] The optical parametric oscillation process is one of the main ways to generate tunable lasers, which has the advantages of a wide wavelength tuning range and rich tuning methods. Optical parametric oscillation is to excite nonlinear crystals with short-wavelength pump lasers to produce long-wavelength signal light and idler light. The signal light is amplified by feedback provided by the resonant cavity. At present, the technical means of using optical parametric oscillators to generate dual-wavelength tunable mid-infrared lasers mainly include: first, using two lasers or dual-wavelength lasers to pump a single-resonance optical parametric oscillator to generate dual-wavelength lasers; second, using a single-wavelength laser to pump a dual-resonance optical parametric oscillator to generate dual-wavelength lasers; third, using a single-wavelength laser to pump an optical parametric oscillator containing two nonlinear crystals to generate dual-wavelength lasers. At present, in the mid-wave infrared range, the above three methods can all achieve dual-wavelength tunable laser output.

[0004] However, it is not possible to use an optical parametric oscillator to achieve simultaneous output of mid-wave infrared and long-wave infrared lasers. The cavity mirror coating of the optical parametric oscillator needs to consider the transmittance of near-infrared pump light and signal light, mid-wave infrared laser and long-wave infrared laser at the same time. Due to the extremely large wavelength span, it is difficult to ensure the quality of the optical film layer while meeting the transmittance requirements of multiple bands. At present, finding a method that can achieve the simultaneous generation of tunable dual-wavelength lasers in the mid-wave infrared and long-wave infrared bands will become an important driving force for the future wider application of mid-infrared technology in security, life sciences, environmental monitoring and other fields. Summary of the invention

[0005] In view of this, the present disclosure provides a tunable dual-wavelength laser generating device and method for mid-wave infrared and long-wave infrared bands, which can simultaneously generate tunable dual-wavelength lasers in the mid-wave infrared and long-wave infrared bands, while reducing the requirements for the coating bandwidth of optical elements and reducing the coating cost.

[0006] One aspect of the present disclosure provides a tunable dual-wavelength laser generating device in the medium-wave infrared and long-wave infrared bands, comprising a laser, an input mirror, a medium-wave infrared nonlinear crystal, a medium-wave infrared output mirror, a total reflection mirror, a long-wave infrared nonlinear crystal and a long-wave infrared output mirror, wherein the input mirror is used to transmit a linearly polarized pulse pump light of a first wavelength generated by the laser to the medium-wave infrared nonlinear crystal, wherein the medium-wave infrared nonlinear crystal is excited by the linearly polarized pulse pump light to generate a first-order signal light of a second wavelength and a medium-wave infrared laser of a third wavelength; the medium-wave infrared output mirror is used to reflect the first-order signal light to the total reflection mirror and output the medium-wave infrared laser by transmission; the total reflection mirror is used to reflect the first-order signal light to the long-wave infrared nonlinear crystal, wherein the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate a second-order signal light of a fourth wavelength and a long-wave infrared laser of a fifth wavelength; and the long-wave infrared output mirror is used to reflect the second-order signal light to the input mirror and output the long-wave infrared laser by transmission.

[0007] According to an embodiment of the present disclosure, an input mirror, a medium-wave infrared output mirror, a total reflection mirror, and a long-wave infrared output mirror constitute an optical parametric oscillator resonant cavity; the first-order signal light and the second-order signal light oscillate in the optical parametric oscillator resonant cavity to amplify the first-order signal light and the second-order signal light.

[0008] According to an embodiment of the present disclosure, a medium-wave infrared nonlinear crystal and a long-wave infrared nonlinear crystal are placed in the resonant cavity of an optical parametric oscillator. When the first-order signal light and the second-order signal light oscillate in the resonant cavity of the optical parametric oscillator, they pass through the medium-wave infrared nonlinear crystal and the long-wave infrared nonlinear crystal.

[0009] According to an embodiment of the present disclosure, the mid-wave infrared nonlinear crystal includes at least one of the following: BaGa 4 Se 7 Crystal, LiInSe 2 Crystal, LiInS 2 Crystal, LiGaSe 2 Crystal, LiGaS 2 Crystal; Long-wave infrared nonlinear crystal includes at least one of the following: BaGa 4 Se 7 Crystal, LiInSe 2 Crystal, LiInS 2 Crystal, LiGaSe 2 Crystal, LiGaS 2.

[0010] According to an embodiment of the present disclosure, the first wavelength, the second wavelength, the third wavelength, the fourth wavelength and the fifth wavelength are different, and the fifth wavelength is greater than the third wavelength.

[0011] According to an embodiment of the present disclosure, the device simultaneously outputs a medium-wave infrared laser of a third wavelength and a long-wave infrared laser of a fifth wavelength, wherein the third wavelength is within the range of 3-5 μm and the fifth wavelength is within the range of 8-12 μm.

[0012] According to an embodiment of the present disclosure, the second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser are related to the first wavelength of the linearly polarized pulse pump light and the transmission angle of the medium-wave infrared nonlinear crystal; the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the second wavelength of the first-order signal light and the transmission angle of the long-wave infrared nonlinear crystal.

[0013] Another aspect of the present disclosure also provides a method for generating tunable dual-wavelength lasers in the medium-wave infrared and long-wave infrared bands, comprising: transmitting a linearly polarized pulse pump light of a first wavelength generated by a laser to a medium-wave infrared nonlinear crystal through an input mirror, so that the medium-wave infrared nonlinear crystal is excited by the linearly polarized pulse pump light to generate a first-order signal light of a second wavelength and a medium-wave infrared laser of a third wavelength; reflecting the first-order signal light to a total reflection mirror through a medium-wave infrared output mirror, and outputting the medium-wave infrared laser through transmission; reflecting the first-order signal light to a long-wave infrared nonlinear crystal through a total reflection mirror, wherein the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate a second-order signal light of a fourth wavelength and a long-wave infrared laser of a fifth wavelength; and reflecting the second-order signal light received from the long-wave infrared nonlinear crystal to the input mirror through a long-wave infrared output mirror, and outputting the long-wave infrared laser through transmission.

[0014] According to an embodiment of the present disclosure, the method also includes: changing the light transmission angle of the medium-wave infrared nonlinear crystal by rotating the medium-wave infrared nonlinear crystal, so that the second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser change; or, changing the light transmission angle of the long-wave infrared nonlinear crystal by rotating the long-wave infrared nonlinear crystal, so that the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser change.

[0015] According to an embodiment of the present disclosure, the method also includes: when the second wavelength of the first-order signal light changes and the transmission angle of the long-wave infrared nonlinear crystal changes, the changes in the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the transmission angle and the second wavelength of the long-wave infrared nonlinear crystal.

[0016] The tunable dual-wavelength laser generating device and method in the mid-wave infrared and long-wave infrared bands provided by the embodiments of the present disclosure can achieve at least one of the following technical effects:

[0017] 1) By adopting the cascade optical parametric process, the first-order signal light generated in the medium-wave infrared nonlinear crystal is used as the pump light of the long-wave infrared nonlinear crystal, and the medium-wave infrared laser and the long-wave infrared laser can be generated simultaneously without the need for excitation of other light sources. In addition, since the second-order signal light generated in the long-wave infrared laser generation process is close to the wavelength of the first-order signal light, and the medium-wave infrared laser and the long-wave infrared laser are output using two output mirrors respectively, the present disclosure can reduce the coating requirements.

[0018] 2) A dual-crystal optical parametric oscillator is used to simultaneously generate medium-wave infrared laser and long-wave infrared laser, and the wavelengths of the dual-wavelength lasers can be changed separately by rotating the light transmission angle of the crystal. As a result, dual-wavelength lasers can be output simultaneously in an ultra-wide wavelength range.

[0019] 3) In the process of cascading optical parameters, since the first-order signal light generated by the medium-wave infrared nonlinear crystal is the pump light of the long-wave infrared nonlinear crystal, the wavelength tuning of the long-wave infrared laser can be achieved by changing the wavelength of the first-order signal light and rotating the light transmission angle of the long-wave infrared nonlinear crystal, and the tuning method is more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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:

[0021] Figure 1 A schematic diagram of a tunable dual-wavelength laser generating device in the mid-wave infrared and long-wave infrared bands according to an embodiment of the present disclosure is schematically shown;

[0022] Figure 2 A schematic diagram of a phase matching method of a cascaded parametric oscillation process according to an embodiment of the present disclosure is schematically shown;

[0023] Figure 3 The flowchart of the method for generating tunable dual-wavelength lasers in the mid-wave infrared and long-wave infrared bands according to an embodiment of the present disclosure is schematically shown;

[0024] Figure 4 A schematic diagram schematically shows the wavelength of the medium-wave infrared laser generated by the medium-wave infrared nonlinear crystal at different light transmission angles according to an embodiment of the present disclosure;

[0025] Figure 5 A schematic diagram schematically shows the wavelength of long-wave infrared lasers generated by a long-wave infrared nonlinear crystal at different light transmission angles according to an embodiment of the present disclosure;

[0026] Figure 6 The diagram schematically shows the wavelength ranges of the output medium-wave infrared laser and long-wave infrared laser when the medium-wave infrared nonlinear crystal and the long-wave infrared nonlinear crystal are rotated simultaneously according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.).

[0031] Figure 1 A schematic diagram of a tunable dual-wavelength laser generating device in the mid-wave infrared and long-wave infrared bands according to an embodiment of the present disclosure is schematically shown.

[0032] like Figure 1 As shown, a tunable dual-wavelength laser generating device for medium-wave infrared and long-wave infrared bands includes a laser 1, an input mirror 2, a medium-wave infrared nonlinear crystal 3, a medium-wave infrared output mirror 4, a total reflection mirror 5, a long-wave infrared nonlinear crystal 6 and a long-wave infrared output mirror 7.

[0033] An input mirror 2 is used to transmit the linearly polarized pulse pump light of the first wavelength generated by the laser 1 to the medium-wave infrared nonlinear crystal 3, wherein the medium-wave infrared nonlinear crystal 3 is excited by the linearly polarized pulse pump light to generate the first-order signal light of the second wavelength and the medium-wave infrared laser of the third wavelength; a medium-wave infrared output mirror 4 is used to reflect the first-order signal light to the total reflection mirror 5, and output the medium-wave infrared laser by transmission; the total reflection mirror 5 is used to reflect the first-order signal light to the long-wave infrared nonlinear crystal 6, wherein the long-wave infrared nonlinear crystal 6 is excited by the first-order signal light to generate the second-order signal light of the fourth wavelength and the long-wave infrared laser of the fifth wavelength; and a long-wave infrared output mirror 7 is used to reflect the second-order signal light to the input mirror 2, and output the long-wave infrared laser by transmission.

[0034] In the embodiments of the present disclosure, by adopting a cascade optical parametric process, the first-order signal light generated in the medium-wave infrared nonlinear crystal is used as the pump light of the long-wave infrared nonlinear crystal, and the medium-wave infrared laser and the long-wave infrared laser can be simultaneously generated without the need for excitation of other light sources. In addition, since the second-order signal light generated in the long-wave infrared laser generation process is close to the wavelength of the first-order signal light, and the medium-wave infrared laser and the long-wave infrared laser are output using two output mirrors respectively, the present disclosure can reduce the coating requirements in the tunable dual-wavelength laser generation device in the medium-wave infrared and long-wave infrared bands.

[0035] The embodiments of the present disclosure can not only simultaneously generate medium-wave infrared and long-wave infrared pulse lasers with independently adjustable wavelengths, but also have a compact system structure and good stability.

[0036] The present invention adopts a cascade optical parametric process, in which the first-order signal light generated by the medium-wave infrared nonlinear crystal is the pump light of the long-wave infrared nonlinear crystal. Therefore, the wavelength tuning of the long-wave infrared laser can be achieved by changing the wavelength of the first-order signal light and rotating the long-wave infrared light transmission angle, and the tuning method is more flexible.

[0037] According to an embodiment of the present disclosure, the laser 1 can emit linearly polarized pulsed pump light with a wavelength of 1064 nm, that is, linearly polarized light. For example, the laser 1 can be a neodymium-doped yttrium aluminum garnet Q-switched laser with a pulse width of nanoseconds and a repetition frequency of 10 Hz.

[0038] According to the embodiments of the present disclosure, the first-order signal light and the second-order signal light are both in the 1.35-1.65 μm band, and the first-order signal light and the second-order signal light share the same coating band, so the coating requirements are relatively low. Specifically:

[0039] The input mirror 2 is coated with a dielectric film, which has high transmission characteristics for linearly polarized pulsed pump light and high reflection characteristics for first-order signal light and second-order signal light. For example, the input mirror 2 can have high transmission characteristics for 1064nm linearly polarized pulsed pump light and high reflection characteristics for first-order signal light and second-order signal light of 1.35-1.65μm. Therefore, when the laser 1 emits a linearly polarized pulsed pump light of the first wavelength, the input mirror 2 can transmit the linearly polarized pulsed pump light to the medium-wave infrared nonlinear crystal 3.

[0040] The medium-wave infrared output mirror 4 is coated with a dielectric film, which has the characteristics of high reflection to linearly polarized pulse pump light, first-order signal light, and second-order signal light, and high transmission to medium-wave infrared light. For example, the medium-wave infrared output mirror 4 coated with the dielectric film has high reflection to 1064nm linearly polarized pulse pump light, 1.35-1.65μm first-order signal light and second-order signal light, and high transmission to 3-5μm medium-wave infrared laser.

[0041] The total reflection mirror 5 is coated with a dielectric film, which has high reflection characteristics for linearly polarized pulse pump light, first-order signal light, and second-order signal light. For example, the total reflection mirror 5 coated with the dielectric film has high reflection for 1064nm linearly polarized pulse pump light, 1.35-1.65μm first-order signal light, and second-order signal light.

[0042] The long-wave infrared output mirror 7 is coated with a dielectric film, which has the characteristics of high reflection for linearly polarized pulse pump light, first-order signal light, and second-order signal light, and high transmission for long-wave infrared light. For example, the long-wave infrared output mirror 7 coated with the dielectric film has high reflection for 1064nm linearly polarized pulse pump light, 1.35-1.65μm first-order signal light and second-order signal light, and high transmission for 8-12μm long-wave infrared laser.

[0043] According to an embodiment of the present disclosure, the input mirror 2, the medium-wave infrared output mirror 4, the total reflection mirror 5, and the long-wave infrared output mirror 7 constitute an optical parametric oscillator resonant cavity; the first-order signal light and the second-order signal light oscillate in the optical parametric oscillator resonant cavity to amplify the first-order signal light and the second-order signal light.

[0044] In this embodiment, the input mirror 2 can transmit the linearly polarized pulse pump light into the optical parametric oscillator resonant cavity, the medium-wave infrared output mirror 4 can transmit the medium-wave infrared laser generated by the medium-wave infrared nonlinear crystal 3 to the outside of the optical parametric oscillator resonant cavity, and output the medium-wave infrared laser; the long-wave infrared output mirror 7 can transmit the long-wave infrared laser generated by the long-wave infrared nonlinear crystal 6 to the outside of the optical parametric oscillator resonant cavity, and output the long-wave infrared laser.

[0045] According to an embodiment of the present disclosure, the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6 are placed in the resonant cavity of the optical parametric oscillator. When the first-order signal light and the second-order signal light oscillate in the resonant cavity of the optical parametric oscillator, they pass through the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6.

[0046] Therefore, in the entire tunable dual-wavelength laser generating device, the first-order signal light and the second-order signal light can not only continuously oscillate and feedback in the optical parametric oscillator resonant cavity, but also continuously superimpose the new first-order signal light and second-order signal light generated by the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6, so as to amplify the first-order signal light and the second-order signal light. Moreover, during the amplification process, the optical parametric oscillator resonant cavity can output medium-wave infrared laser and long-wave infrared laser at the same time. In addition, since the wavelength of the second-order signal light is close to that of the first-order signal light, and the medium-wave infrared laser and the long-wave infrared laser are output by two output mirrors respectively, the present disclosure can reduce the coating requirements for the tunable dual-wavelength laser generating device in the medium-wave infrared and long-wave infrared bands, especially the coating requirements for the optical parametric oscillator resonant cavity.

[0047] According to an embodiment of the present disclosure, the medium-wave infrared nonlinear crystal 3 includes at least one of the following: BaGa 4 Se 7 Crystal, LiInSe 2 Crystal, LiInS 2 Crystal, LiGaSe 2 Crystal, LiGaS 2 Crystal; long-wave infrared nonlinear crystal 7 includes at least one of the following: BaGa 4 Se 7 Crystal, LiInSe 2 Crystal, LiInS 2 Crystal, LiGaSe 2 Crystal, LiGaS 2 Crystal.

[0048] According to the embodiments of the present disclosure, both the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6 are nonlinear optical crystals with a high laser damage threshold, a large band gap and a wide light transmission band. The linearly polarized pulse pump light generated by the laser 1 enters the medium-wave infrared nonlinear crystal 3 through the transmission of the input mirror 2. The linearly polarized pulse pump light can excite the nonlinear optical frequency conversion process (i.e., the optical parameter process) of the medium-wave infrared nonlinear crystal 3, thereby generating a first-order signal light of a second wavelength and a medium-wave infrared laser of a third wavelength. Similarly, after the first-order signal light reflected by the total reflection mirror 5 enters the long-wave infrared nonlinear crystal 6, the first-order signal light excites the nonlinear optical frequency conversion process of the long-wave infrared nonlinear crystal 6, thereby generating a second-order signal light of a fourth wavelength and a long-wave infrared laser of a fifth wavelength.

[0049] According to an embodiment of the present disclosure, the first wavelength, the second wavelength, the third wavelength, the fourth wavelength and the fifth wavelength are different, and the fifth wavelength is greater than the third wavelength.

[0050] According to an embodiment of the present disclosure, the device simultaneously outputs a medium-wave infrared laser of a third wavelength and a long-wave infrared laser of a fifth wavelength, wherein the third wavelength is within the range of 3-5 μm and the fifth wavelength is within the range of 8-12 μm.

[0051] For example, the mid-wave infrared nonlinear crystal 3 may be BaGa 4 Se 7 Crystal, cutting angle is θ1=52.2°, φ=0°, the two end faces facing the input mirror 2 and the medium-wave infrared output mirror 4 are coated with 1064nm, 1.35-1.65μm, 3-5μm high-transmittance dielectric film; long-wave infrared nonlinear crystal 6 is BaGa 4 Se 7 The crystal has a cutting angle of θ2=42.4° and φ=0°, and the two end surfaces facing the total reflection mirror 5 and the long-wave infrared output mirror 7 are coated with high-transmittance dielectric films for 1064nm, 1.35-1.65μm, and 8-12μm.

[0052] According to an embodiment of the present disclosure, the second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser are related to the first wavelength of the linearly polarized pulse pump light and the transmission angle of the medium-wave infrared nonlinear crystal 3; the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the second wavelength of the first-order signal light and the transmission angle of the long-wave infrared nonlinear crystal 6.

[0053] According to the embodiments of the present disclosure, the light transmission angle refers to the angle between the light transmission direction of the medium-wave infrared nonlinear crystal 3 / long-wave infrared nonlinear crystal 6 and the crystal axis, which can also be called the phase matching angle in the crystal. There is a corresponding relationship between the phase matching angle of the medium-wave infrared nonlinear crystal 3 and the output medium-wave infrared laser, and there is a corresponding relationship between the phase matching angle of the long-wave infrared nonlinear crystal 6 and the output long-wave infrared laser.

[0054] In the field of optics, the wave vector of light = 2π / wavelength. The relationship between the output light and the input light of the medium-wave infrared nonlinear crystal 3 and the relationship between the output light and the input light of the long-wave infrared nonlinear crystal 6 will be described below by using the wave vector.

[0055] Figure 2 A schematic diagram of a phase matching method in a cascaded parametric oscillation process according to an embodiment of the present disclosure is shown schematically.

[0056] like Figure 2 As shown, k p is the wave vector of the linearly polarized pulse pump light, k mis the wave vector of the mid-wave infrared laser, k s1 is the wave vector of the first-order signal light, k s2 is the wave vector of the second-order signal light, k l is the wave vector of the long-wave infrared laser.

[0057] The polarization direction of the linearly polarized pulse pump light is vertical, and the polarization directions of the first-order signal light and the medium-wave infrared laser are horizontal. p =k m +k s1 , the type I phase matching condition is satisfied in the mid-wave infrared nonlinear crystal 3.

[0058] The polarization direction of the second-order signal light and the long-wave infrared laser is vertical, k s1 =k l +k s2 , the type I phase matching condition is satisfied in the long-wave infrared nonlinear crystal 6.

[0059] k p , k m , k s1 , k l , k s2 The value is related to the angle between the wave vector and the crystal axis, that is, it is related to the light transmission angle. When the light transmission angle of the medium-wave infrared nonlinear crystal 3 remains unchanged and the wave vector / first wavelength of the linearly polarized pulse pump light changes, the wave vector / second wavelength of the first-order signal light and the wave vector / third wavelength of the medium-wave infrared laser will change accordingly; when the wave vector / first wavelength of the linearly polarized pulse pump light remains unchanged and the light transmission angle changes, the wave vector / second wavelength of the first-order signal light and the wave vector / third wavelength of the medium-wave infrared laser will also change accordingly. The above changes satisfy k p =k m +k s1 Similarly, when the transmission angle of the long-wave infrared nonlinear crystal 6 remains unchanged and the wave vector / second wavelength of the first-order signal light changes, the wave vector / fourth wavelength of the second-order signal light and the wave vector / fifth wavelength of the long-wave infrared laser will change accordingly; when the wave vector / second wavelength of the first-order signal light remains unchanged and the transmission angle changes, the wave vector / fourth wavelength of the second-order signal light and the wave vector / fifth wavelength of the long-wave infrared laser will also change accordingly. The above changes satisfy k s1 =k l +k s2 relationship.

[0060] Therefore, by rotating the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6 and changing the light transmission direction and the angle between the crystal axes, the phase matching condition can be changed to achieve wavelength tuning of the medium-wave infrared laser and the long-wave infrared laser output.

[0061] It should be noted that, during the cascade parametric oscillation process, if the transmission angle of the medium-wave infrared nonlinear crystal 3 is changed, the wave vector of the first-order signal light changes, and the wave vector / fourth wavelength of the second-order signal light and the wave vector / fifth wavelength of the long-wave infrared laser will also change accordingly.

[0062] In the embodiments of the present disclosure, a dual-crystal optical parametric oscillator is used to simultaneously generate a medium-wave infrared laser and a long-wave infrared laser, and the wavelengths of the dual-wavelength lasers can be changed respectively by rotating the light transmission angle of the crystal, thereby achieving simultaneous output of dual-wavelength lasers within an ultra-wide wavelength range. In addition, in the cascade optical parameter process, since the first-order signal light generated by the medium-wave infrared nonlinear crystal is the pump light of the long-wave infrared nonlinear crystal, the wavelength tuning of the long-wave infrared laser can be achieved by changing the wavelength of the first-order signal light and rotating the light transmission angle of the long-wave infrared nonlinear crystal, and the tuning method is more flexible.

[0063] Figure 3 The flowchart of the method for generating tunable dual-wavelength lasers in the mid-wave infrared and long-wave infrared bands according to an embodiment of the present disclosure is schematically shown.

[0064] like Figure 3 As shown, embodiment 300 includes operations S310 to S340.

[0065] In operation S310, the linearly polarized pulse pump light of the first wavelength generated by the laser is transmitted to the medium-wave infrared nonlinear crystal through the input mirror, so that the medium-wave infrared nonlinear crystal is excited by the linearly polarized pulse pump light to generate the first-order signal light of the second wavelength and the medium-wave infrared laser of the third wavelength.

[0066] In operation S320, the first-order signal light is reflected to a total reflection mirror through a medium-wave infrared output mirror, and medium-wave infrared laser light is output through transmission.

[0067] In operation S330, the first-order signal light is reflected to the long-wave infrared nonlinear crystal through the total reflection mirror, wherein the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate the second-order signal light of the fourth wavelength and the long-wave infrared laser of the fifth wavelength.

[0068] In operation S340, the second-order signal light is reflected to the input mirror through the long-wave infrared output mirror, and the long-wave infrared laser is output by transmission.

[0069] In the embodiments of the present disclosure, by adopting a cascade optical parametric process, the first-order signal light generated in the medium-wave infrared nonlinear crystal is used as the pump light of the long-wave infrared nonlinear crystal, and the medium-wave infrared laser and the long-wave infrared laser can be simultaneously generated without the need for excitation of other light sources. In addition, since the second-order signal light generated in the long-wave infrared laser generation process is close to the wavelength of the first-order signal light, and the medium-wave infrared laser and the long-wave infrared laser are output using two output mirrors respectively, the present disclosure reduces the coating requirements for the resonant cavity of the optical parametric oscillator.

[0070] According to an embodiment of the present disclosure, the method further comprises: changing the light transmission angle of the medium-wave infrared nonlinear crystal 3 by rotating the medium-wave infrared nonlinear crystal (3), so that the second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser are changed; or changing the light transmission angle of the long-wave infrared nonlinear crystal 6 by rotating the long-wave infrared nonlinear crystal 6, so that the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are changed.

[0071] Figure 4 A schematic diagram schematically shows the wavelength of the medium-wave infrared laser generated by the medium-wave infrared nonlinear crystal at different light transmission angles according to an embodiment of the present disclosure.

[0072] like Figure 4 As shown, the long-wave infrared nonlinear crystal 6 is fixed, and the medium-wave infrared nonlinear crystal 3 is rotated so that the angle between the crystal axis and the light transmission direction changes between 51.3-58.9°. Accordingly, the wavelength of the output medium-wave infrared laser changes continuously within the range of 3.0-5.0 μm. At this time, the tunable dual-wavelength laser generating device in the medium-wave infrared and long-wave infrared bands can not only realize the simultaneous output of medium-wave infrared and long-wave infrared lasers, but also realize the tunable wavelength of the medium-wave infrared laser.

[0073] Figure 5 A schematic diagram schematically shows the wavelength of long-wave infrared laser generated by a long-wave infrared nonlinear crystal at different light transmission angles according to an embodiment of the present disclosure.

[0074] like Figure 5 As shown, the medium-wave infrared nonlinear crystal 3 is fixed, and the medium-wave infrared nonlinear crystal 6 is rotated so that the angle between the crystal axis and the light transmission direction changes between 41.8-42.3°. Accordingly, the output long-wave infrared laser wavelength changes continuously within the range of 9.2-12.1 μm. At this time, the tunable dual-wavelength laser generating device in the medium-wave infrared and long-wave infrared bands can not only realize the simultaneous output of medium-wave infrared and long-wave infrared lasers, but also realize the tunable wavelength of the long-wave infrared laser.

[0075] According to an embodiment of the present disclosure, the method also includes: when the second wavelength of the first-order signal light changes and the transmission angle of the long-wave infrared nonlinear crystal 6 changes, the changes in the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the transmission angle and the second wavelength of the long-wave infrared nonlinear crystal 6.

[0076] Figure 6 The diagram schematically shows the wavelength ranges of the output medium-wave infrared laser and long-wave infrared laser when the medium-wave infrared nonlinear crystal and the long-wave infrared nonlinear crystal are rotated simultaneously according to the embodiment of the present disclosure.

[0077] like Figure 6 As shown, by changing the phase matching angle of the medium-wave infrared nonlinear crystal 3 and the phase matching angle of the long-wave infrared nonlinear crystal 6, the wavelength tuning of the output long-wave infrared laser can be achieved. Under different phase matching angle conditions of the medium-wave infrared nonlinear crystal 3, such as θ1=51.31°, θ1=52.20°, and θ1=53.07°, the medium-wave infrared nonlinear crystal 6 is rotated so that the angle between the crystal axis and the light transmission direction changes between 41.8-42.3°. In this way, the wavelength tuning of the medium-wave infrared laser and the long-wave infrared laser can be achieved simultaneously.

[0078] In the embodiment of the present disclosure, the wavelengths of the output medium-wave infrared laser and the long-wave infrared laser can be continuously changed by changing the light transmission angle of the medium-wave infrared nonlinear crystal 3 and the long-wave infrared nonlinear crystal 6. Compared with the traditional single tuning method, the wavelength tuning method of the medium- and long-wave infrared laser disclosed in the present disclosure is more flexible.

[0079] Except for special instructions on the models of various devices in the embodiments of the present disclosure, there is no limitation on the models of other devices, as long as the devices can complete the above functions.

[0080] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of 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 combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0081] 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 tunable dual-wavelength laser generating device in the mid-wave infrared and long-wave infrared bands, characterized in that: The device comprises: a laser, an input mirror, a medium-wave infrared nonlinear crystal, a medium-wave infrared output mirror, a total reflection mirror, a long-wave infrared nonlinear crystal and a long-wave infrared output mirror, wherein: The input mirror is used to transmit the linearly polarized pulse pump light of the first wavelength generated by the laser to the medium-wave infrared nonlinear crystal, wherein the medium-wave infrared nonlinear crystal is excited by the linearly polarized pulse pump light to generate the first-order signal light of the second wavelength and the medium-wave infrared laser of the third wavelength; The medium-wave infrared output mirror is used to reflect the first-order signal light to the total reflection mirror and output the medium-wave infrared laser by transmission; The total reflection mirror is used to reflect the first-order signal light to the long-wave infrared nonlinear crystal, wherein the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate the second-order signal light of the fourth wavelength and the long-wave infrared laser of the fifth wavelength; and The long-wave infrared output mirror is used to reflect the second-order signal light to the input mirror and output the long-wave infrared laser by transmission.

2. The device according to claim 1, characterized in that The input mirror, the medium-wave infrared output mirror, the total reflection mirror, and the long-wave infrared output mirror constitute an optical parametric oscillator resonant cavity; The first-order signal light and the second-order signal light oscillate in the optical parametric oscillator resonant cavity to amplify the first-order signal light and the second-order signal light.

3. The device according to claim 2, characterized in that The medium-wave infrared nonlinear crystal and the long-wave infrared nonlinear crystal are placed in the resonant cavity of an optical parametric oscillator. When the first-order signal light and the second-order signal light oscillate in the resonant cavity of the optical parametric oscillator, they pass through the medium-wave infrared nonlinear crystal and the long-wave infrared nonlinear crystal.

4. The device according to claim 1, characterized in that The medium-wave infrared nonlinear crystal includes at least one of the following: BaGa4Se7 crystal, LiInSe2 crystal, LiInS2 crystal, LiGaSe2 crystal, LiGaS2 crystal; The long-wave infrared nonlinear crystal includes at least one of the following: BaGa4Se7 crystal, LiInSe2 crystal, LiInS2 crystal, LiGaSe2 crystal, LiGaS2 crystal.

5. The device according to claim 1, characterized in that The first wavelength, the second wavelength, the third wavelength, the fourth wavelength, and the fifth wavelength are different, and the fifth wavelength is greater than the third wavelength.

6. The device according to claim 1, characterized in that The device simultaneously outputs the medium-wave infrared laser of a third wavelength and the long-wave infrared laser of a fifth wavelength, wherein the third wavelength is within the range of 3-5 μm, and the fifth wavelength is within the range of 8-12 μm.

7. The device according to claim 1, characterized in that The second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser are related to the first wavelength of the linearly polarized pulse pump light and the light transmission angle of the medium-wave infrared nonlinear crystal; The fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the second wavelength of the first-order signal light and the transmission angle of the long-wave infrared nonlinear crystal.

8. A method for generating tunable dual-wavelength lasers in the mid-wave infrared and long-wave infrared bands, characterized in that: The method comprises: The linearly polarized pulse pump light of the first wavelength generated by the laser is transmitted to the medium-wave infrared nonlinear crystal through an input mirror, so that the medium-wave infrared nonlinear crystal is excited by the linearly polarized pulse pump light to generate a first-order signal light of the second wavelength and a medium-wave infrared laser of the third wavelength; Reflecting the first-order signal light to the total reflection mirror through the medium-wave infrared output mirror, and outputting the medium-wave infrared laser through transmission; Reflecting the first-order signal light to the long-wave infrared nonlinear crystal through the total reflection mirror, wherein the long-wave infrared nonlinear crystal is excited by the first-order signal light to generate second-order signal light of a fourth wavelength and long-wave infrared laser light of a fifth wavelength; and The second-order signal light is reflected to the input mirror through the long-wave infrared output mirror, and the long-wave infrared laser is output by transmission.

9. The method according to claim 8, characterized in that The method further comprises: By rotating the medium-wave infrared nonlinear crystal to change the light transmission angle of the medium-wave infrared nonlinear crystal, the second wavelength of the first-order signal light and the third wavelength of the medium-wave infrared laser light are changed; or, The light transmission angle of the long-wave infrared nonlinear crystal is changed by rotating the long-wave infrared nonlinear crystal, so that the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are changed.

10. The method according to claim 9, characterized in that The method further comprises: When the second wavelength of the first-order signal light changes and the transmission angle of the long-wave infrared nonlinear crystal changes, changes in the fourth wavelength of the second-order signal light and the fifth wavelength of the long-wave infrared laser are related to the transmission angle of the long-wave infrared nonlinear crystal and the second wavelength.

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