Dual-wavelength narrow-linewidth tunable all-solid-state laser

Abstract

The invention provides a dual-wavelength narrow-linewidth tunable all-solid-state laser, and relates to the technical field of lasers, and the laser comprises a dual-wavelength laser pumping source which is used for providing dual-wavelength pumping laser; the optical parametric oscillator is used for obtaining narrow-linewidth tunable dual-wavelength parametric light under the action of the dual-wavelength pumping laser; the optical parametric oscillator comprises an input mirror used for inputting the dual-wavelength pumping laser provided by the dual-wavelength laser pumping source to the optical parametric oscillator; the first nonlinear crystal is used for realizing nonlinear frequency conversion of the dual-wavelength pumping laser and generating dual-wavelength parametric light; the beam splitter is used for splitting the dual-wavelength parametric light into first wavelength parametric light and second wavelength parametric light; and the parametric light resonant cavity comprises a diffraction grating group, a high-reflectivity mirror group and an output mirror, frequency selection is performed on the first wavelength parametric light and the second wavelength parametric light based on the diffraction grating group and the high-reflectivity mirror group, the output line width of the dual-wavelength parametric light is narrowed, and the dual-wavelength parametric light with the narrowed line width is output based on the output mirror.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and more particularly to a dual-wavelength narrow-linewidth tunable all-solid-state laser. Background Art

[0002] Remote sensing of toxic and harmful gases in the atmosphere is a crucial component of environmental quality monitoring. Infrared wavelengths encompass the characteristic absorption peaks of many toxic gases, and lasers in this wavelength range are commonly used for toxic gas detection. Differential Absorption Lidar (DIAL) systems, with their active detection capabilities, long range, and high accuracy, are widely used for measuring and monitoring a variety of toxic gases.

[0003] Traditional DIAL systems typically use two tunable lasers as light sources, emitting two laser pulses with different central wavelengths into the measured space. This requires additional beam combining and timing synchronization systems, resulting in high volume, power consumption, and system complexity. To meet the high-precision detection requirements for a variety of toxic gases, DIAL systems also place high demands on the laser source's output power, tuning range, tuning speed, and spectral linewidth.

[0004] Conventional dual-wavelength lasers are directly realized using a single or multiple laser gain media, which have disadvantages such as difficult tuning and fixed wavelength intervals, limiting their practical application in multi-component toxic gas detection. Optical Parametric Oscillator (OPO), as a nonlinear frequency conversion technology, has the characteristics of simple structure and easy wide-range wavelength tuning, and is often used for laser wavelength extension. However, due to the spectral line broadening effect during the optical parametric oscillation process, the output linewidth of OPO is generally wide (5-20 cm -1 The output linewidth varies significantly with the output wavelength, making it difficult to meet the requirements of high-precision detection. It is worth noting that traditional dual-wavelength lasers typically use an etalon array to narrow the dual-wavelength laser. However, multiple etalons cause mutual interference between the two wavelength oscillations, leading to a surge in intracavity losses and a sharp drop in conversion efficiency, making it impossible to simultaneously meet the requirements of high-power and narrow-linewidth lasers. Furthermore, the technology for narrowing the linewidth of dual-wavelength optical parametric oscillators remains largely undeveloped. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] The present invention provides a dual-wavelength narrow-linewidth tunable all-solid-state laser, which is used to at least partially solve one of the above technical problems.

[0007] (2) Technical solution

[0008] According to a first aspect of the present invention, a dual-wavelength narrow-linewidth tunable all-solid-state laser is provided, comprising: a dual-wavelength laser pump source for providing dual-wavelength pump laser light; an optical parametric oscillator for obtaining narrow-linewidth tunable dual-wavelength parametric light under the action of the dual-wavelength pump laser light; wherein the optical parametric oscillator comprises: an input mirror for inputting the dual-wavelength pump laser light provided by the dual-wavelength laser pump source into the optical parametric oscillator; a first nonlinear crystal for achieving nonlinear frequency conversion of the dual-wavelength pump laser light to generate dual-wavelength parametric light; a beam splitter for splitting the dual-wavelength parametric light into a first wavelength parametric light and a second wavelength parametric light; a parametric optical resonant cavity comprising a diffraction grating group, a high-reflection mirror group, and an output mirror, wherein the first wavelength parametric light and the second wavelength parametric light are frequency-selected based on the diffraction grating and the high-reflection mirror, and the output linewidth of the dual-wavelength parametric light is narrowed, and the output mirror is used to output the dual-wavelength parametric light with the narrowed linewidth.

[0009] According to an embodiment of the present invention, the diffraction grating group in the parametric resonant cavity includes a first wavelength diffraction grating and a second wavelength diffraction grating, and the first wavelength diffraction grating and the second wavelength diffraction grating are respectively arranged at different ends of the beam splitter. The first wavelength diffraction grating is used to diffract the first wavelength parametric light and narrow the output linewidth of the first wavelength parametric light; the second wavelength diffraction grating is used to diffract the second wavelength parametric light and narrow the output linewidth of the second wavelength parametric light.

[0010] According to an embodiment of the present invention, the parametric optical resonant cavity is any one of a Littman cavity structure and a Littrow cavity structure, and the diffraction grating is a single dispersion element or a combination of multiple dispersion elements.

[0011] According to an embodiment of the present invention, the output mirror surface is coated with a first dielectric film and a second dielectric film.

[0012] The first dielectric film is used for partially transmitting the first wavelength parametric light and the second wavelength parametric light; the second dielectric film is used for totally reflecting the dual-wavelength pump laser.

[0013] According to an embodiment of the present invention, the high-reflection mirror group includes: a first high-reflection mirror, which is used to reflect the zero-order diffraction light of the first wavelength parametric light, and the first high-reflection mirror and the output mirror together form a resonant cavity of the first wavelength parametric light; a second high-reflection mirror, which is used to reflect the first-order diffraction light of the signal light or the idler light in the first wavelength parametric light, and the second high-reflection mirror and the output mirror together form a resonant cavity sub-cavity of the first wavelength parametric light, which is used to perform wavelength selection and linewidth narrowing of the first wavelength parametric light; a third high-reflection mirror, which is used to reflect the zero-order diffraction light of the second wavelength parametric light The output mirror is used to reflect the first-order diffraction light of the signal light or the idler light in the second wavelength parametric light, and the third high-reflective mirror and the output mirror together form a resonant cavity of the second wavelength parametric light, which is used to perform wavelength selection and linewidth narrowing of the second wavelength parametric light; wherein the first high-reflective mirror and the second high-reflective mirror are respectively arranged at different ends of the first wavelength diffraction grating, and the third high-reflective mirror and the fourth high-reflective mirror are respectively arranged at different ends of the second wavelength diffraction grating.

[0014] According to an embodiment of the present invention, it also includes: a first wavelength selective element and a second wavelength selective element, the first wavelength selective element is arranged between the first wavelength diffraction grating and the second high-reflection mirror, and is used to achieve linewidth narrowing of the first wavelength parametric light; the second wavelength selective element is arranged between the second wavelength diffraction grating and the fourth high-reflection mirror, and is used to achieve linewidth narrowing of the second wavelength parametric light.

[0015] According to an embodiment of the present invention, the input mirror is coated with a dielectric film that partially transmits the dual-wavelength pump laser; the input mirror is combined with the output mirror to couple the dual-wavelength pump laser and the dual-wavelength parametric light multiple times in the cavity.

[0016] According to an embodiment of the present invention, the beam splitter is coated with a dielectric film that is highly transparent to the first wavelength parametric light and highly reflective to the second wavelength parametric light; the beam splitter is any one of a 45° beam splitter, a prism, and a transmission grating.

[0017] According to an embodiment of the present invention, it also includes an optical parametric amplifier: arranged at the output end of the optical parametric oscillator, used to amplify the narrow-linewidth tunable dual-wavelength parametric light generated by the optical parametric oscillator; the optical parametric amplifier includes: a beam combiner, used to combine the dual-wavelength pump laser generated by the dual-wavelength laser pump source and the dual-wavelength parametric light generated by the optical parametric oscillator; a second nonlinear crystal, used to amplify the narrow-linewidth tunable dual-wavelength parametric light generated by the optical parametric oscillator under the pumping action of the dual-wavelength pump laser.

[0018] According to an embodiment of the present invention, the optical attenuator further includes: an adjustable attenuator, which is provided at the output end of the dual-wavelength laser pump source and is used to adjust the laser power of the dual-wavelength pump laser injected into the optical parametric oscillator and the optical parametric amplifier; the adjustable attenuator includes: a first half-wave plate, which is used to adjust the polarization direction of the dual-wavelength pump laser; and a polarizer, which is used to split the dual-wavelength pump 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.

[0019] (3) Beneficial effects

[0020] The dual-wavelength narrow-linewidth tunable all-solid-state laser provided by the present invention has at least the following beneficial effects:

[0021] (1) The dual-wavelength narrow-linewidth tunable all-solid-state laser provided in the embodiment of the present invention is based on the nonlinear frequency conversion technology of optical parametric oscillation, which expands the output wavelength and tuning capability of the dual-wavelength laser. A diffraction grating is used as the resonant cavity of the optical parametric oscillator. Based on the wavelength dispersion and selection function of the grating, combined with the frequency selection element, the effective narrowing of the output linewidth of the dual-wavelength laser can be achieved. In addition, by collaboratively controlling the angles of the nonlinear crystal and the high-reflection mirror, a dual-wavelength tunable laser output with a wide tuning range can be obtained. The dual-wavelength laser has a simple structure and is easy to use. It can meet the requirements of differential absorption laser radar for remote detection of toxic gases for the output wavelength, spectral linewidth and tuning capability of the light source.

[0022] (2) The dual-wavelength narrow-linewidth tunable all-solid-state laser provided in the embodiments of the present invention adopts a Littman composite cavity structure based on a dual-grating. By designing that the two resonant cavities share the same output coupling mirror, the surge in intracavity loss caused by the frequency-selective element in the traditional single-cavity structure is improved, and the independent linewidth narrowing and cooperative tuning of the dual-wavelength laser can be achieved. This cavity structure can significantly improve the spectral purity and tuning flexibility of the dual-wavelength laser, providing an efficient and stable technical solution for achieving narrow-linewidth tunable dual-wavelength laser output. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0024] Figure 1 The structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to an embodiment of the present invention is schematically shown;

[0025] Figure 2 A schematic diagram shows the structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to another embodiment of the present invention;

[0026] Figure 3The structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to another embodiment of the present invention is schematically shown.

[0027] Reference numerals

[0028] 100-dual-wavelength laser pump source; 101-first beam coupling module; 102-isolator; 103-second beam coupling module; 104-third beam coupling module; 210-input mirror; 220-beam splitter; 2301-first wavelength diffraction grating; 2302-second wavelength diffraction grating; 2401-first high-reflection mirror; 2402-second high-reflection mirror; 2403-third high-reflection mirror; 2404-fourth high-reflection mirror; 2501-first beam splitter; 2502-second beam splitter; 260-first nonlinear crystal; 270-output mirror; 310-first wavelength frequency-selective element; 320-second wavelength frequency-selective element; 301-first half-wave plate; 302-polarizer; 303-second half-wave plate; 304-reflector; 305-beam combiner; 306-second nonlinear crystal. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0031] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or mutual communication; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] In the description of the present invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0033] Throughout the drawings, identical elements are represented by identical or similar reference numerals. Conventional structures or configurations may be omitted where they may obscure the understanding of the present invention. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect actual size, proportion, or actual positional relationships. Furthermore, any reference symbols placed between parentheses should not be construed as limiting.

[0034] Similarly, in order to streamline the present invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" and the like mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0036] An embodiment of the present invention provides a dual-wavelength narrow-linewidth tunable all-solid-state laser. Before introducing the technical solution provided by the embodiment of the present invention, the related technologies involved in the present invention are first described.

[0037] To meet the high-precision detection needs of various toxic gases, the DIAL system places high demands on the laser source's output power, tuning range, tuning speed, and spectral linewidth. Traditional dual-wavelength lasers typically directly achieve dual-wavelength output using a single or multiple laser gains. This presents challenges such as difficult tuning and a fixed wavelength spacing, limiting the application scope of the DIAL system and making it incapable of meeting the diverse toxic gas detection requirements.

[0038] Optical parametric oscillation (OPO) technology is commonly used to extend laser wavelengths. However, due to the spectral broadening effect during the OPO process, existing OPOs generally have a relatively wide output linewidth. Furthermore, this linewidth varies significantly with the output wavelength, making it difficult to meet the requirements of high-precision detection.

[0039] In addition, traditional dual-wavelength lasers usually use an etalon set to narrow the dual-wavelength laser, but multiple etalons will cause mutual interference between the dual-wavelength oscillations, resulting in a surge in intracavity losses and reduced conversion efficiency.

[0040] To address the problems of wide output linewidth, significant wavelength-dependent linewidth variation, and gain competition and interference between dual-wavelength lasers in existing optical parametric oscillators, the inventors proposed a dual-wavelength narrow-linewidth tunable all-solid-state laser by inserting a diffraction grating group into the resonant cavity of the optical parametric oscillator.

[0041] When broadband laser light is incident on the grating surface, different wavelength components are spatially separated due to differences in diffraction angles, enabling frequency-selective feedback through geometric optical path manipulation. Based on this principle, the inventors constructed a dual-grating Littman composite cavity architecture. By further combining the grating's dispersion characteristics with cavity mode control, they achieved effective linewidth narrowing and wavelength tuning for dual-wavelength lasers.

[0042] An embodiment of the present invention provides a dual-wavelength narrow-linewidth tunable all-solid-state laser, comprising: a dual-wavelength laser pump source for providing dual-wavelength pump laser light; an optical parametric oscillator for obtaining narrow-linewidth tunable dual-wavelength parametric light under the action of the dual-wavelength pump laser light; wherein the optical parametric oscillator comprises: an input mirror for inputting the dual-wavelength pump laser light provided by the dual-wavelength laser pump source into the optical parametric oscillator; a first nonlinear crystal for achieving nonlinear frequency conversion of the dual-wavelength pump laser light to generate dual-wavelength parametric light; a beam splitter for splitting the dual-wavelength parametric light into a first wavelength parametric light and a second wavelength parametric light; a parametric light resonant cavity comprising a diffraction grating group, a high-reflection mirror group, and an output mirror, wherein the first wavelength parametric light and the second wavelength parametric light are frequency-selected based on the diffraction grating and the high-reflection mirror, and the output linewidth of the dual-wavelength parametric light is narrowed, and the dual-wavelength parametric light with the narrowed linewidth is output based on the output mirror.

[0043] Figure 1 The structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to an embodiment of the present invention is schematically shown.

[0044] See also Figure 1 The dual-wavelength narrow-linewidth tunable all-solid-state laser of this embodiment includes: a dual-wavelength laser pump source 100 and an optical parametric oscillator.

[0045] The dual-wavelength laser pump source 100 is used to provide dual-wavelength pump lasers to pump an optical parametric oscillator.

[0046] The dual-wavelength laser pump source 100 is a linearly polarized dual-wavelength laser source that outputs linearly polarized dual-wavelength pulsed laser light in a specified wavelength band. In some embodiments, the output wavelength can be 1 μm (e.g., a dual-wavelength Nd-doped laser), 2 μm (e.g., a dual-wavelength Tm and Ho co-doped laser), or 3 μm (e.g., a dual-wavelength Er-doped laser).

[0047] The optical parametric oscillator is used to obtain narrow-linewidth tunable dual-wavelength parametric light under the pumping action of the dual-wavelength pump laser.

[0048] In some embodiments, the dual-wavelength parametric light can be any one of dual-wavelength idler light, dual-wavelength signal light, dual-wavelength idler light and dual-wavelength signal light, corresponding to single resonance of idler light, single resonance of signal light, and dual resonance of idler light and signal light, respectively. The present invention is not limited here.

[0049] The optical parametric oscillator includes an input mirror 210 , a first nonlinear crystal 260 , a beam splitter 220 , a diffraction grating group, a high-reflection mirror group, and an output mirror 270 .

[0050] The input mirror 210 is used to input the dual-wavelength pump laser provided by the dual-wavelength laser pump source 100 into the optical parametric oscillator.

[0051] The first nonlinear crystal 260 is used to implement nonlinear frequency conversion of the dual-wavelength pump laser to generate dual-wavelength parametric light.

[0052] In some embodiments, the first nonlinear crystal 260 is a second-order nonlinear crystal. The second-order nonlinear crystal has a low absorption coefficient for the dual-wavelength pump laser, the dual-wavelength idler light, and the dual-wavelength signal light, and is coated with a corresponding antireflection coating. Alternatively, the first nonlinear crystal 260 can be a typical visible-band nonlinear crystal, such as β-barium metaborate (β-BaB2O4) or lithium triborate (LiB3O5), a typical near-infrared nonlinear crystal, such as potassium titanyl phosphate (KTiOPO4) or lithium niobate (LiNbO3), or a typical mid- and far-infrared nonlinear crystal, such as zinc germanium phosphate (ZnGeP2) or barium gallium selenide (BaGa4Se7). By selecting nonlinear crystals of different wavelengths, dual-wavelength laser output in different wavelength bands can be achieved.

[0053] The beam splitter 220 is used to split the dual-wavelength parametric light into the first wavelength parametric light and the second wavelength parametric light.

[0054] In some embodiments, the beam splitter 220 can be a 45° beam splitter coated with high transmittance of the first wavelength parametric light and high reflectance of the second parametric light, or it can be other beam splitting elements such as a prism and a transmission grating. Those skilled in the art can choose according to actual needs, and the present invention is not limited here.

[0055] The diffraction grating group is used to diffract the dual-wavelength parametric light and narrow the output linewidth of the dual-wavelength parametric light. The high-reflection mirror group is used to reflect the dual-wavelength parametric light. The output mirror 270 is used to output the dual-wavelength parametric light after the linewidth is narrowed. The diffraction grating group, the high-reflection mirror group, and the output mirror 270 together constitute the Littman resonant cavity of the dual-wavelength parametric light. It should be noted that, in addition to the Littman resonant cavity, the parametric light resonant cavity can also be a Littrow cavity structure, and technicians can choose according to actual needs, and the present invention is not limited here. The diffraction grating can be a single dispersion element or a combination of multiple dispersion elements, wherein the dispersion element can be, for example, a transmission grating, a prism, etc.

[0056] In some embodiments, the diffraction grating set includes a first-wavelength diffraction grating 2301 and a second-wavelength diffraction grating 2302. The first-wavelength diffraction grating 2301 and the second-wavelength diffraction grating 2302 may be reflective ruled gratings with different blaze angles. Specifically, the first-wavelength diffraction grating 2301 is configured to diffract parametric light of a first wavelength and narrow the output linewidth of the parametric light of the first wavelength; the second-wavelength diffraction grating 2302 is configured to diffract parametric light of a second wavelength and narrow the output linewidth of the parametric light of the second wavelength.

[0057] In some embodiments, the high-reflection mirror group includes a first high-reflection mirror 2401, a second high-reflection mirror 2402, a third high-reflection mirror 2403, and a fourth high-reflection mirror 2404. The first high-reflection mirror 2401 and the second high-reflection mirror 2402 are respectively disposed at different ends of the first wavelength diffraction grating 2301. The third high-reflection mirror 2403 and the fourth high-reflection mirror 2404 are respectively disposed at different ends of the second wavelength diffraction grating 2302.

[0058] The first highly reflective mirror 2401 is configured to reflect the zeroth-order diffracted light of the parametric light of the first wavelength. The first highly reflective mirror 2401 and the output mirror 270 together form a resonant cavity for the parametric light of the first wavelength. The second highly reflective mirror 2402 is configured to reflect the first-order diffracted light of the signal light or idler light in the parametric light of the first wavelength. The second highly reflective mirror 2402 and the output mirror 270 together form a sub-cavity for the resonant cavity for the parametric light of the first wavelength, and are configured to perform wavelength selection and linewidth narrowing of the parametric light of the first wavelength.

[0059] The third high-reflective mirror 2403 is used to reflect the zero-order diffraction light of the second wavelength parametric light. The third high-reflective mirror 2403 and the output mirror 270 together constitute a resonant cavity of the second wavelength parametric light. The fourth high-reflective mirror 2404 is used to reflect the first-order diffraction light of the signal light or the idler light in the second wavelength parametric light. The fourth high-reflective mirror 2404 and the output mirror 270 together constitute a resonant cavity sub-cavity of the second wavelength parametric light, which is used to perform wavelength selection and linewidth narrowing of the second wavelength parametric light.

[0060] In some embodiments, the first nonlinear crystal 260 , the second high-reflection mirror 2402 , and the fourth high-reflection mirror 2404 are all configured with an angle adjustment function, and the coordinated tuning of narrow-linewidth dual-wavelength lasers can be achieved by changing the phase matching conditions.

[0061] Exemplarily, the linewidth narrowing process is described by taking the first wavelength diffraction grating and the second high-reflection mirror as an example.

[0062] Parametric light is incident on a diffraction grating, where the angular dispersion of the first-wavelength diffraction grating converts wavelength deviations into spatial deviations. First-order diffracted light at the target wavelength is precisely reflected back to the grating by the second highly reflective mirror, forming a closed optical path. Due to the change in diffraction angle, the deviated wavelength cannot be effectively reflected by the second highly reflective mirror, resulting in energy loss and suppression. Only wavelengths within a very narrow range near the target wavelength can form stable oscillations, achieving active wavelength selection. The resonant cavity formed by the second highly reflective mirror and the output mirror enhances feedback through multiple reflections, thereby achieving a narrowed linewidth of the output laser.

[0063] The output mirror 270 is used to output dual-wavelength parametric light.

[0064] In some embodiments, the output mirror 270 is coated with a first dielectric film and a second dielectric film. The first dielectric film is used to partially transmit the first wavelength parametric light and the second wavelength parametric light; the second dielectric film is used to fully reflect the dual-wavelength pump laser.

[0065] In some embodiments, the input mirror 210 is coated with a third dielectric film that partially transmits the dual-wavelength pump laser. Combining the input mirror 210 with the output mirror 270 allows for multiple coupling of the dual-wavelength pump laser and the dual-wavelength parametric light within the cavity, improving the parametric conversion efficiency of the dual-wavelength pump laser.

[0066] The dual-grating Littman composite cavity structure, with two resonant cavities sharing the same output coupling mirror, mitigates the surge in intracavity losses caused by the frequency-selective element in traditional single-cavity structures, enabling independent linewidth narrowing and coordinated tuning of dual-wavelength lasers. This cavity structure significantly improves the spectral purity and tuning flexibility of dual-wavelength lasers, providing an efficient and stable technical solution for achieving narrow-linewidth tunable dual-wavelength laser output.

[0067] The dual-wavelength narrow-linewidth tunable all-solid-state laser provided in the embodiment of the present invention may further include a first beam coupling module 101 and an isolator 102 .

[0068] In some embodiments, the first beam coupling module 101 is used to adjust the size and position of the pump light waist output by the dual-wavelength laser pump source 100, so that the pump light spot waist of the dual-wavelength pump source is located at the center of the first nonlinear crystal 260. By adjusting the size of the pump light waist, the output linewidth and output efficiency can be adjusted.

[0069] In some embodiments, the isolator 102 is disposed between the dual-wavelength laser pump source 100 and the input mirror 210 to block the reflected dual-wavelength pump laser to prevent it from damaging the dual-wavelength laser pump source 100 .

[0070] The dual-wavelength narrow-linewidth tunable all-solid-state laser provided in the embodiment of the present invention may further include a first beam splitter 2501 disposed in the optical parametric oscillator resonant cavity.

[0071] In some embodiments, the first beam splitter 2501 is disposed between the first nonlinear crystal 260 and the beam splitter 220 to reflect the dual-wavelength pump laser generated by the dual-wavelength laser pump source 100 to the first nonlinear crystal 260 and transmit the dual-wavelength parametric light.

[0072] To facilitate those skilled in the art to understand the propagation path of light in the dual-wavelength narrow linewidth tunable all-solid-state laser provided by the embodiment of the present invention, Figure 1 Different lines are used to represent different types of light. Figure 1 , the solid line represents the dual-wavelength pump laser of the first wavelength output by the dual-wavelength laser pump source 100, which is used to pump the first nonlinear crystal 260; the dotted line represents the dual-wavelength parametric light generated by the optical parametric oscillator, which is the dual-wavelength signal light and the dual-wavelength idler light in the embodiment of the present invention.

[0073] The dual-wavelength narrow-linewidth tunable all-solid-state laser provided by the embodiment of the present invention is based on the nonlinear frequency conversion technology of optical parametric oscillation, which expands the output wavelength and tuning capability of the dual-wavelength laser. A diffraction grating group is inserted into the resonant cavity of the optical parametric oscillator. Based on the wavelength dispersion and selection function of the grating, combined with the frequency selection element, the effective narrowing of the output linewidth of the dual-wavelength laser can be achieved. In addition, by collaboratively controlling the angles of the nonlinear crystal and the high-reflection mirror, a dual-wavelength tunable laser output with a wide tuning range can be obtained. The dual-wavelength laser has a simple structure and is easy to use. It can meet the requirements of the differential absorption laser radar for remote sensing of toxic gases for the output wavelength, spectral linewidth and tuning capability of the light source.

[0074] Figure 2The structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to another embodiment of the present invention is schematically shown.

[0075] like Figure 2 As shown, the dual-wavelength narrow linewidth tunable all-solid-state laser further includes: a frequency selection element group for achieving linewidth narrowing of the dual-wavelength parametric light.

[0076] It should be noted that for other implementation details of the dual-wavelength narrow linewidth tunable all-solid-state laser of this embodiment, please refer to Figure 1 The dual-wavelength narrow-linewidth tunable all-solid-state laser shown is not described in detail here.

[0077] In some embodiments, the frequency selective element group may include, for example, a first wavelength frequency selective element 310 and a second wavelength frequency selective element 320 .

[0078] The first wavelength selective element 310 is provided between the first wavelength diffraction grating 2301 and the second high-reflection mirror 2402, and is used to achieve linewidth narrowing of the first wavelength parametric light; the second wavelength selective element 320 is provided between the second diffraction grating and the fourth high-reflection mirror 2404, and is used to achieve linewidth narrowing of the second wavelength parametric light.

[0079] In some embodiments, the first wavelength selective element 310 and the second wavelength selective element 320 may be, for example, a Fabry-Perot etalon, a birefringent filter, etc., and may be a single frequency selective element or a combination of multiple frequency selective elements.

[0080] By adding a frequency-selective element between the diffraction grating and the high-reflection mirror, the linewidth narrowing accuracy of the parametric light can be effectively improved, thereby achieving laser output with a narrower linewidth.

[0081] Figure 3 The structure of a dual-wavelength narrow-linewidth tunable all-solid-state laser according to another embodiment of the present invention is schematically shown.

[0082] like Figure 3 As shown, the dual-wavelength narrow-linewidth tunable all-solid-state laser further includes: an optical parametric amplifier and an adjustable attenuator.

[0083] It should be noted that for other implementation details of the dual-wavelength narrow linewidth tunable all-solid-state laser of this embodiment, please refer to Figure 1 or Figure 2 The dual-wavelength narrow-linewidth tunable all-solid-state laser shown is not described in detail here.

[0084] An optical parametric amplifier (OPA) is located at the output of the optical parametric oscillator (OPO) to amplify the narrow-linewidth, tunable, dual-wavelength parametric light generated by the OPO. A tunable attenuator (TAD) is located at the output of the dual-wavelength laser pump source 100 to adjust the power of the dual-wavelength pump laser injected into the OPO and OPA.

[0085] In some embodiments, the optical parametric amplifier includes a beam combiner 305 and a second nonlinear crystal 306 .

[0086] The beam combining mirror 305 is provided at the output end of the optical parametric oscillator, and is used to combine the dual-wavelength pump laser generated by the dual-wavelength laser pump source 100 and the dual-wavelength parametric light generated by the optical parametric oscillator.

[0087] The second nonlinear crystal 306 is used to amplify the narrow-linewidth tunable dual-wavelength parametric light generated by the optical parametric oscillator under the pumping action of the dual-wavelength pump laser.

[0088] In some embodiments, the second nonlinear crystal 306 is a second-order nonlinear crystal with a low absorption coefficient for both the dual-wavelength pump laser and the dual-wavelength parametric light, and is coated with a corresponding antireflection coating. After the dual-wavelength pump laser passes through the variable attenuator, one of the dual-wavelength pump lasers passes through the second beam coupling module 103, the reflector 304, and the beam combiner 305. It is then injected into the second nonlinear crystal 306 simultaneously with the coupled dual-wavelength parametric light, achieving amplification of the narrow-linewidth tunable dual-wavelength laser.

[0089] In some embodiments, the adjustable attenuator includes a first half-wave plate 301 and a polarizer 302 .

[0090] The first half-wave plate 301 is used to adjust the polarization direction of the dual-wavelength pump laser.

[0091] The polarizer 302 is used to split the dual-wavelength pump 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.

[0092] Continue to see Figure 3 The dual-wavelength narrow-linewidth tunable all-solid-state laser may further include: a second half-wave plate 303 and a second beam splitter 2502 .

[0093] The second half-wave plate 303 is provided between the polarizer 302 and the beam combiner 305 and is used to adjust the polarization state of the dual-wavelength pump laser injected into the optical parametric oscillator to meet the phase matching condition of the optical parametric amplifier.

[0094] The third beam splitter 2503 is disposed at one end of the second nonlinear crystal 306 and is configured to reflect the remaining dual-wavelength pump laser light after passing through the second nonlinear crystal 306 and transmit the dual-wavelength parametric light, wherein the dual-wavelength parametric light includes the dual-wavelength signal light and the dual-wavelength idler light.

[0095] The dual-wavelength narrow-linewidth tunable all-solid-state laser provided in an embodiment of the present invention adopts a full-chain system of "dual-wavelength laser pump source → optical parametric oscillator → optical parametric amplifier" to achieve narrow-linewidth tunable dual-wavelength laser output with high beam quality.

[0096] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Those skilled in the art may make various substitutions and modifications without departing from the scope of the present invention, and such substitutions and modifications are intended to be included within the scope of protection of the present invention.

Claims

1. A dual-wavelength narrow-linewidth tunable all-solid-state laser, characterized in that: include: A dual-wavelength laser pump source (100) is used to provide dual-wavelength pump laser; An optical parametric oscillator is used to obtain narrow-linewidth tunable dual-wavelength parametric light under the action of a dual-wavelength pump laser; Wherein, the optical parametric oscillator comprises: An input mirror (210) is used to input the dual-wavelength pump laser provided by the dual-wavelength laser pump source (100) into the optical parametric oscillator; A first nonlinear crystal (260) is used to realize nonlinear frequency conversion of the dual-wavelength pump laser to generate dual-wavelength parametric light; A beam splitter (220) for splitting the dual-wavelength parametric light into first-wavelength parametric light and second-wavelength parametric light; A parametric light resonant cavity comprises a diffraction grating group, a high-reflection mirror group and an output mirror (270), performs frequency selection on the first wavelength parametric light and the second wavelength parametric light based on the diffraction grating and the high-reflection mirror, narrows the output linewidth of the dual-wavelength parametric light, and outputs the dual-wavelength parametric light with the narrowed linewidth based on the output mirror (270).

2. The dual-wavelength narrow linewidth tunable all-solid-state laser according to claim 1, characterized in that: The diffraction grating group in the parametric resonant cavity comprises a first wavelength diffraction grating (2301) and a second wavelength diffraction grating (2302), wherein the first wavelength diffraction grating (2301) and the second wavelength diffraction grating (2302) are respectively arranged at different ends of the beam splitter (220). The first wavelength diffraction grating (2301) is used to diffract the first wavelength parametric light and narrow the output linewidth of the first wavelength parametric light; The second wavelength diffraction grating (2302) is used to diffract the second wavelength parametric light and narrow the output linewidth of the second wavelength parametric light.

3. The dual-wavelength narrow linewidth tunable all-solid-state laser according to claim 1, characterized in that: The parametric optical resonant cavity is any one of a Littman cavity structure and a Littrow cavity structure, and the diffraction grating is a single dispersion element or a combination of multiple dispersion elements.

4. The dual-wavelength narrow linewidth tunable all-solid-state laser according to claim 1, characterized in that: The surface of the output mirror (270) is coated with a first dielectric film and a second dielectric film. The first dielectric film is used to partially transmit the first wavelength parametric light and the second wavelength parametric light; The second dielectric film is used for totally reflecting the dual-wavelength pump laser.

5. The dual-wavelength narrow linewidth tunable all-solid-state laser according to claim 2, characterized in that: The high reflective mirror group includes: a first high-reflection mirror (2401) for reflecting zero-order diffraction light of the parametric light of the first wavelength, wherein the first high-reflection mirror (2401) and the output mirror (270) together form a resonant cavity of the parametric light of the first wavelength; a second high-reflection mirror (2402) for reflecting first-order diffracted light of the first-wavelength parametric light, wherein the second high-reflection mirror (2402) and the output mirror (270) together form a resonant cavity sub-cavity of the first-wavelength parametric light, and are used to perform wavelength selection and linewidth narrowing of the first-wavelength parametric light; a third high-reflection mirror (2403) for reflecting zero-order diffraction light of the second wavelength parametric light, wherein the third high-reflection mirror (2403) and the output mirror (270) together form a resonant cavity of the second wavelength parametric light; a fourth high-reflection mirror (2404) for reflecting first-order diffracted light of the second wavelength parametric light, wherein the fourth high-reflection mirror (2404) and the output mirror (270) together form a resonant cavity sub-cavity of the second wavelength parametric light, and are used to perform wavelength selection and linewidth narrowing of the second wavelength parametric light; The first high-reflection mirror (2401) and the second high-reflection mirror (2402) are respectively arranged at different ends of the first wavelength diffraction grating (2301), and the third high-reflection mirror (2403) and the fourth high-reflection mirror (2404) are respectively arranged at different ends of the second wavelength diffraction grating (2302).

6. The dual-wavelength narrow-linewidth tunable all-solid-state laser according to claim 5, characterized in that: Also includes: a first wavelength frequency-selective element (310) and a second wavelength frequency-selective element (320), The first wavelength frequency selection element (310) is provided between the first wavelength diffraction grating (2301) and the second high-reflection mirror (2402), and is used to achieve line width narrowing of the first wavelength parametric light; The second wavelength frequency selection element (320) is provided between the second wavelength diffraction grating (2302) and the fourth high-reflection mirror (2404) and is used to achieve line width narrowing of the second wavelength parametric light.

7. The dual-wavelength narrow-linewidth tunable all-solid-state laser according to claim 1, characterized in that: The input mirror (210) is coated with a dielectric film that partially transmits the dual-wavelength pump laser; The input mirror (210) is combined with the output mirror (270) to couple the dual-wavelength pump laser and the dual-wavelength parametric light multiple times in the cavity.

8. The dual-wavelength narrow linewidth tunable all-solid-state laser according to claim 1, characterized in that: The beam splitter (220) is coated with a dielectric film that is highly transparent to the first wavelength parametric light and highly reflective to the second wavelength parametric light; The beam splitter is any one of a 45° beam splitter, a prism, and a transmission grating.

9. The dual-wavelength narrow-linewidth tunable all-solid-state laser according to claim 1 or 6, characterized in that: Also includes optical parametric amplifiers: The optical parametric amplifier is provided at the output end of the optical parametric oscillator and is used to amplify the narrow linewidth tunable dual-wavelength parametric light generated by the optical parametric oscillator; The optical parametric amplifier comprises a beam combining mirror (305) and a second nonlinear crystal (306); The beam combining mirror (305) is used to combine the dual-wavelength pump laser generated by the dual-wavelength laser pump source (100) and the dual-wavelength parametric light generated by the optical parametric oscillator; The second nonlinear crystal (306) is used to amplify the narrow linewidth tunable dual-wavelength parametric light generated by the optical parametric oscillator under the pumping action of the dual-wavelength pump laser.

10. The dual-wavelength narrow-linewidth tunable all-solid-state laser according to claim 9, characterized in that: Also includes an adjustable attenuator, The adjustable attenuator is provided at the output end of the dual-wavelength laser pump source, and is used to adjust the laser power of the dual-wavelength pump laser injected into the optical parametric oscillator and the optical parametric amplifier; The adjustable attenuator comprises a first half-wave plate (301) and a polarizing plate (302), The first half-wave plate (301) is used to adjust the polarization direction of the dual-wavelength pump laser; The polarizer (302) is used to divide the dual-wavelength pump 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.

Images