Chromium-doped gain medium solid laser based on thulium solid laser pumping

Abstract

The invention provides a chromium-doped gain medium solid laser based on thulium solid laser pumping. Comprising a pumping source, a pumping light coupling device, a first laser lens, a thulium-doped laser gain medium, a first laser coupling output lens, a light coupling device, a second laser lens, a chromium-doped laser gain medium and a second laser coupling output lens which are arranged in sequence, the thulium-doped laser gain medium is a thulium-doped solid gain medium; the chromium-doped laser gain medium is a chromium-doped solid gain medium; a first oscillation cavity of laser is constructed between the first laser lens and the first laser coupling output lens; and a second oscillation cavity of the laser is constructed between the second laser lens and the second laser coupling output lens, and is used for wavelength selection to realize the output of the laser at the wave band of 1.9-3 microns. The thulium-doped solid laser is used as a pumping source to pump the chromium-doped crystal, so that the problem that the chromium-doped crystal is low in pumping efficiency and output power under other pumping sources such as an optical fiber laser is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid lasers, and in particular relates to a chromium-doped gain medium solid laser based on thulium solid laser pumping. Background Art

[0002] Cr2+:ZnSe laser is an ideal light source for gas detection, remote sensing, optical communication and other fields. Since Cr2+ ions have a wide absorption spectrum (1.5-2.1μm), there are many options for pumping sources. The wavelength for pumping Cr2+:ZnSe is usually around 2μm. The absorption peak of Cr2+ ions is around 1.75μm, and there are currently few lasers that can provide effective pumping in this band. Therefore, in order to obtain high-power laser output in Cr2+:ZnSe and Cr2+:ZnS lasers, the choice of pumping light source is crucial.

[0003] At present, there are three main options for Cr2+:ZnSe pump sources: diode lasers (LD), thulium-doped fiber lasers, and holmium-doped or thulium-doped all-solid-state lasers. Diode lasers with InGaAsP as gain media are located at 1.6-1.9μm, which can improve the electro-optical conversion efficiency and effectively reduce costs. However, the brightness of the laser output from such semiconductor lasers is poor, and the output power of chromium-doped lasers directly pumped by LD is generally low; Thulium-doped fiber lasers can control the output wavelength of the laser to a wavelength near the absorption peak of cr2+ ions, such as 1.83μm, by adding a wavelength selector, which can greatly improve the optical-optical conversion efficiency, but the wavelength selector of thulium-doped fiber lasers is relatively expensive and difficult to popularize in industry. In addition, there are some uncommon pump options, such as 1.75-2.1μm tunable Co2+:MgF2 lasers and 1.5-2μm optical parametric lasers, but these lasers are expensive and easily damaged when used as pumps. The selection of pump source should take into full consideration factors such as quantum loss and absorption coefficient. If the quantum loss is large, heat will be deposited inside the Cr2+:ZnSe crystal, and the enhanced thermal effect will reduce the laser operation efficiency. Summary of the invention

[0004] The technical purpose of the present invention is to provide a chromium-doped gain medium solid laser based on thulium solid laser pumping, using the thulium-doped solid laser as a pump source to pump the chromium-doped crystal, and by improving the light-to-light conversion efficiency, the high-power output of the chromium-doped laser can be achieved.

[0005] To solve the above technical problems, the present invention is implemented as follows: a chromium-doped gain medium solid laser based on thulium solid laser pumping, comprising a pump source, a pump light coupling device, a first laser lens, a thulium-doped laser gain medium, a first laser coupling output lens, an optical coupling device, a second laser lens, a chromium-doped laser gain medium and a second laser coupling output lens arranged in sequence; wherein the thulium-doped laser gain medium is a thulium-doped solid gain medium; the chromium-doped laser gain medium is a chromium-doped solid gain medium with laser gain characteristics; a first oscillation cavity of the laser is constructed between the first laser lens and the first laser coupling output lens; a second oscillation cavity of the laser is constructed between the second laser lens and the second laser coupling output lens, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium and output laser with a wavelength of 2.4 microns.

[0006] Furthermore, the thulium-doped laser gain medium is any one of thulium-doped glass, thulium-doped crystal or thulium-doped laser ceramic.

[0007] Furthermore, the first laser lens and the first laser coupling output lens form a stable cavity, and the cavity type is any one of: flat-flat, flat-concave, and concave-flat cavity.

[0008] Furthermore, the second oscillation cavity is any one of a FP cavity, a folded cavity or a ring cavity.

[0009] Further, the first laser lens is used to transmit the laser light provided by the pump source and the laser light emitted by the thulium-doped laser gain medium with a reflection reflectivity greater than 99.5%;

[0010] The first laser coupling output lens is used to transmit the laser emitted by the thulium-doped laser gain medium, and its transmittance in the wavelength band above 1900nm is greater than 90%.

[0011] Furthermore, the second laser lens is used for passing the laser light emitted by the thulium-doped laser gain medium and reflecting the laser light emitted by the chromium-doped laser gain medium, and the reflectivity thereof is greater than 99.5%.

[0012] Furthermore, the second laser coupling output lens is used to transmit the laser emitted by the chromium-doped laser gain medium, and its transmittance is no more than 50%.

[0013] Furthermore, it is used to achieve the output of laser in the 1.9-3 μm band.

[0014] Furthermore, it also includes a first reflector and a second reflector located between the optical path of the chromium-doped laser gain medium and the second laser coupling output lens, the first reflector is used to reflect the laser output by the chromium-doped laser gain medium, and the second reflector is used to receive the laser reflected by the first reflector and reflect it to the second laser coupling output lens, wherein the reflectivity of the first reflector and the second reflector to the laser emitted by the chromium-doped laser gain medium is greater than 99.5%.

[0015] Furthermore, it also includes a first reflective lens and a second reflective lens located between the optical path of the chromium-doped laser gain medium and the second laser coupling output lens, the first reflective lens is used to reflect the laser output by the chromium-doped laser gain medium, the second reflective lens is used to receive the laser reflected by the first reflective lens and reflect it to the second laser coupling output lens, and the second laser lens is used to reflect the laser emitted by the chromium-doped laser gain medium to the second laser coupling output lens, wherein the reflectivity of the first reflective mirror and the second reflective mirror to the laser emitted by the chromium-doped laser gain medium is greater than 99.5%.

[0016] Compared with the prior art, the chromium-doped gain medium solid laser pumped by thulium solid laser in the present invention has the following beneficial effects:

[0017] The pump source is used to provide a laser with a wavelength that can be absorbed by the thulium-doped laser gain medium; the pump optical coupling device is used to focus the laser provided by the pump source into the thulium-doped laser gain medium, and the optical coupling device is used to couple and focus the laser emitted by the thulium-doped laser gain medium into the chromium-doped laser gain medium, wherein the thulium-doped laser gain medium is a thulium-doped solid gain medium; the chromium-doped laser gain medium is a chromium-doped solid gain medium with laser gain characteristics; a first oscillation cavity of the laser is constructed between the first laser lens and the first laser coupling output lens; a second oscillation cavity of the laser is constructed between the second laser lens and the second laser coupling output lens, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium and output a laser with a wavelength of 2.4 microns. The present invention adopts a thulium-doped solid laser as a pump source to pump a chromium-doped crystal, and the pump absorption efficiency can reach 80%, and the output power can reach 1W, which solves the problem that the pump efficiency and output power of the chromium-doped crystal are not high under other pump sources such as fiber lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the first structural layout of a chromium-doped gain medium solid laser pumped by a thulium solid laser in an embodiment of the present invention;

[0019] Figure 21 is a schematic diagram of a second structural layout of a chromium-doped gain medium solid laser pumped by a thulium solid laser in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the third structural layout of a chromium-doped gain medium solid laser pumped by a thulium solid laser in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0022] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “circumferential”, “radial”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] Combination Figure 1, a chromium-doped gain medium solid laser based on thulium solid laser pumping is provided, comprising a pump source 1, a pump light coupling device 2, a first laser lens 3, a thulium-doped laser gain medium 4, a first laser coupling output lens 5, an optical coupling device 6, a second laser lens 7, a chromium-doped laser gain medium 8 and a second laser coupling output lens 9 arranged in sequence; wherein the thulium-doped laser gain medium 4 is a thulium-doped solid gain medium; the chromium-doped laser gain medium 8 is a chromium-doped solid gain medium with laser gain characteristics; a first oscillation cavity of the laser is constructed between the first laser lens 3 and the first laser coupling output lens 5; a second oscillation cavity of the laser is constructed between the second laser lens 7 and the second laser coupling output lens 9, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium 8, so as to realize the output of the laser in the 1.9-3μm band, such as outputting the laser with a wavelength of 2.4 microns.

[0025] In the present scheme, the pump source 1 is used to provide a laser with a wavelength that can be absorbed by the thulium-doped laser gain medium 4; the pump light coupling device 2 is used to focus the laser provided by the pump source 1 into the thulium-doped laser gain medium 4, and the light coupling device 6 is used to couple and focus the laser emitted by the thulium-doped laser gain medium 4 into the chromium-doped laser gain medium 8, wherein the thulium-doped laser gain medium 4 is a thulium-doped solid gain medium; the chromium-doped laser gain medium 8 is a chromium-doped solid gain medium with laser gain characteristics; a first oscillation cavity of the laser is constructed between the first laser lens 3 and the first laser coupling output lens 5; a second oscillation cavity of the laser is constructed between the second laser lens 7 and the second laser coupling output lens 9, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium 8 and output a laser with a wavelength of 2.4 microns. The present invention adopts a thulium-doped solid laser as a pump source 1 to pump a chromium-doped crystal, and the pump efficiency can reach 80% absorption efficiency and the output power can reach 1W, thereby solving the problem of low pump efficiency and output power of the chromium-doped crystal under other pump sources 1 such as fiber lasers.

[0026] Furthermore, the thulium-doped laser gain medium 4 is any one of thulium-doped glass, thulium-doped crystal or thulium-doped laser ceramic.

[0027] Furthermore, the lenses of the first laser lens 3 and the first laser coupling output lens 5 form a stable cavity, and the cavity type is any one of: flat-flat, flat-concave, and concave-flat cavity. Among them, the first laser lens 3 is used to pass the laser provided by the pump source 1 with a high pass rate and reflect the laser emitted by the thulium-doped laser gain medium 4 with a high reflectivity. Its pass rate for the laser provided by the pump source is greater than 90%, and its reflectivity for the laser emitted by the thulium-doped laser gain medium 4 is greater than 99.5%; the first laser coupling output lens 5 is used to pass the laser emitted by the thulium-doped laser gain medium 4 with a high pass rate, and its transmittance for the band above 1900nm is greater than 90%. The first laser lens 3 and the first laser coupling output lens 5 form a first oscillation cavity, which can form positive feedback for laser oscillation, and is used to select the wavelength of the generated laser and output laser in the mid-infrared band.

[0028] Furthermore, the second oscillation cavity is any one of a FP cavity, a folded cavity or a ring cavity.

[0029] Furthermore, the second laser lens 7 is used to transmit the laser emitted by the thulium-doped laser gain medium 4 and reflect the laser emitted by the chromium-doped laser gain medium 8 with a high pass rate, and the reflectivity is greater than 99.5%; the second laser coupling output lens 9 is used to transmit the laser emitted by the chromium-doped laser gain medium 8, and its transmittance is not greater than 50%. The chromium-doped laser gain medium 8 is a chromium-doped solid gain medium with laser gain characteristics. The second laser lens 7 and the second laser coupling output lens 9 form a second oscillation cavity, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium 8 and output a laser with a wavelength of 2.4 microns.

[0030] Combination Figure 2 In one embodiment, the second oscillation cavity is a folded cavity, and the chromium-doped gain medium solid laser pumped by a thulium solid laser further includes a first reflector 10 and a second reflector 11 located between the optical path of the chromium-doped laser gain medium 8 and the second laser coupling output lens 9, wherein the first reflector 10 is used to reflect the laser output by the chromium-doped laser gain medium 8, and the second reflector 11 is used to receive the laser reflected by the first reflector 10 and reflect it to the second laser coupling output lens 9, wherein the reflectivity of the first reflector 10 and the second reflector 11 to the laser emitted by the chromium-doped laser gain medium 8 is greater than 99.5%. Specifically, in this embodiment, the pump source 1, the pump light coupling device 2, the first laser lens 3, the thulium-doped laser gain medium 4, the first laser coupling output lens 5, the light coupling device 6, the second laser lens 7, the chromium-doped laser gain medium 8 and the first reflector 10 are arranged in a straight line, and the angle between the first reflector 10 and the straight line is 30 to 75°, preferably 45°. The second reflector 11 and the second laser coupling output lens 9 are arranged in a straight line and parallel to the arrangement direction from the pump source 1 to the first reflector 10.

[0031] Among them, the second laser lens 7, the first reflector 10, the second reflector 11 and the second laser coupling output lens 9 together constitute a lens group of the folded resonant cavity. The pump light emitted by the pump source 1 passes through the pump coupling device, is collimated and focused by the pump coupling device, and then acts on the thulium-doped solid laser gain medium through the first laser lens 3. The thulium-doped solid laser gain medium produces a particle number inversion under the action of the focused pump light, thereby generating a laser. The generated laser is oscillated and reflected by the first laser lens 3 and the first laser coupling output lens 5, and then output through the first laser coupling output lens 5. As pump light, it is coupled and focused by the optical coupling device 6 and acts on the chromium-doped solid gain medium through the second laser lens 7. The second laser lens 7, the second laser coupling output lens 9 and the second reflector 11 in this folded cavity can pass the laser provided by the thulium-doped laser gain medium 4 with high transmittance, and can reflect the laser emitted by the chromium-doped laser gain medium 8 with high reflectivity. The second laser coupling output lens 9 has a certain transmittance to the laser emitted by the chromium-doped laser gain medium 8. The folded cavity can introduce a grating element instead of the mirror 10 or the mirror 11 to act as a wavelength tuning element.

[0032] Combination Figure 3 In one embodiment, the second oscillation cavity is a ring cavity, and the chromium-doped gain medium solid laser pumped by the thulium solid laser further includes a first reflector 10 and a second reflector 11 located between the optical path of the chromium-doped laser gain medium 8 and the second laser coupling output lens 9, the first reflector 10 is used to reflect the laser output by the chromium-doped laser gain medium 8, the second reflector 11 is used to receive the laser reflected by the first reflector 10 and reflect it to the second laser coupling output lens 9, and the second laser lens 7 is used to reflect the laser emitted by the chromium-doped laser gain medium 8 to the second laser coupling output lens 9, wherein the reflectivity of the first reflector 10 and the second reflector 11 to the laser emitted by the chromium-doped laser gain medium 8 is greater than 99.5%. Specifically, in this embodiment, the pump source 1, the pump light coupling device 2, the first laser lens 3, the thulium-doped laser gain medium 4, the first laser coupling output lens 5, the light coupling device 6, the second laser lens 7, the chromium-doped laser gain medium 8 and the first reflector 10 are arranged in a straight line, the angle between the second laser lens 7 and the straight line is 30 to 75°, preferably 45°, the angle between the first reflector 10 and the straight line is 30 to 75°, preferably 45°, the second reflector 11 and the second laser coupling output lens 9 are arranged along a straight line and parallel to the arrangement direction from the pump source 1 to the first reflector 10, and the second laser coupling output lens 9 is tilted so that it can receive the light reflected by the second laser lens 7.

[0033] Among them, the second laser lens 7, the first reflector 10, the second reflector 11 and the second laser coupling output lens 9 together constitute a lens group of the ring resonator. The pump light emitted by the pump source 1 passes through the pump coupling device, is collimated and focused by the pump coupling device, and then acts on the thulium-doped solid laser gain medium through the first laser lens 3. The thulium-doped solid laser gain medium produces a particle number inversion under the action of the focused pump light, thereby generating a laser. The generated laser is oscillated and reflected by the first laser lens 3 and the first laser coupling output lens 5, and then output through the first laser coupling output lens 5. As pump light, it is coupled and focused by the optical coupling device 6 and acts on the chromium-doped solid gain medium through the second laser lens 7. The second laser lens 7, the second laser coupling output lens 9 and the second reflector 11 in this folded cavity can pass the laser provided by the thulium-doped laser gain medium 4 with high transmittance, and can reflect the laser emitted by the chromium-doped laser gain medium 8 with high reflectivity. The second laser coupling output lens 9 has a certain transmittance to the laser emitted by the chromium-doped laser gain medium 8. This type of folded cavity can form traveling wave oscillation of laser and realize narrow linewidth laser output.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A chromium-doped gain medium solid laser pumped by a thulium solid laser, characterized in that: It includes a pump source, a pump light coupling device, a first laser lens, a thulium-doped laser gain medium, a first laser coupling output lens, an optical coupling device, a second laser lens, a chromium-doped laser gain medium and a second laser coupling output lens arranged in sequence; wherein the thulium-doped laser gain medium is a thulium-doped solid gain medium; the chromium-doped laser gain medium is a chromium-doped solid gain medium with laser gain characteristics; a first oscillation cavity of the laser is constructed between the first laser lens and the first laser coupling output lens; a second oscillation cavity of the laser is constructed between the second laser lens and the second laser coupling output lens, which is used to select the wavelength of the laser generated by the chromium-doped laser gain medium and output laser with a wavelength of 2.4 microns.

2. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The thulium-doped laser gain medium is any one of thulium-doped glass, thulium-doped crystal or thulium-doped laser ceramic.

3. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The first laser lens and the first laser coupling output lens form a stable cavity, and the cavity type is any one of flat-flat, flat-concave, and concave-flat cavity.

4. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The second oscillation cavity is any one of an FP cavity, a folded cavity or a ring cavity.

5. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The first laser lens is used to reflect the laser light provided by the pump source and the laser light emitted by the thulium-doped laser gain medium with a reflectivity greater than 99.5%; The first laser coupling output lens is used to transmit the laser emitted by the thulium-doped laser gain medium, and its transmittance in the wavelength band above 1900nm is greater than 90%.

6. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The second laser lens is used for passing the laser light emitted by the thulium-doped laser gain medium and reflecting the laser light emitted by the chromium-doped laser gain medium, and the reflectivity thereof is greater than 99.5%.

7. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: The second laser coupling output lens is used to transmit the laser emitted by the chromium-doped laser gain medium, and its transmittance is no more than 50%.

8. The chromium-doped gain medium solid laser pumped by thulium solid laser according to claim 1, characterized in that: Used to achieve the output of laser in the 1.9~3μm band.

9. The chromium-doped gain medium solid laser pumped by a thulium solid laser according to any one of claims 1 to 8, characterized in that: It also includes a first reflector and a second reflector located between the optical path of the chromium-doped laser gain medium and the second laser coupling output lens, the first reflector is used to reflect the laser output by the chromium-doped laser gain medium, and the second reflector is used to receive the laser reflected by the first reflector and reflect it to the second laser coupling output lens, wherein the reflectivity of the first reflector and the second reflector to the laser emitted by the chromium-doped laser gain medium is greater than 99.5%.

10. The chromium-doped gain medium solid laser pumped by a thulium solid laser according to any one of claims 1 to 8, characterized in that: It also includes a first reflective mirror and a second reflective mirror located between the optical path of the chromium-doped laser gain medium and the second laser coupling output mirror, the first reflective mirror is used to reflect the laser output by the chromium-doped laser gain medium, the second reflective mirror is used to receive the laser reflected by the first reflective mirror and reflect it to the second laser coupling output mirror, and the second laser mirror is used to reflect the laser emitted by the chromium-doped laser gain medium to the second laser coupling output mirror, wherein the reflectivity of the first reflective mirror and the second reflective mirror to the laser emitted by the chromium-doped laser gain medium is greater than 99.5%.

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