A multi-wavelength infrared laser output device

Abstract

The application discloses a kind of multi-wavelength infrared laser output device, comprising: a nonlinear crystal with displacement function, two three-prism, at least four mirror cavity mirror;Pump light is incident on nonlinear crystal by first three-prism, and first signal light and first idler light are generated;By second three-prism, it is dispersed into three light paths, wherein first signal light is blocked by a first output mirror, and the reflected part of light beam is incident on first total reflection mirror again through two three-prism and nonlinear crystal, and total reflection is returned, and in the cavity, it is amplified and oscillated, and pump light and first idler light are completely output;Output can select two wavelengths or one, which are first signal light and first idler light respectively;By adjusting the position of nonlinear crystal, nonlinear crystal is moved to the position of another polarization period, and second signal light and second idler light are generated.The application makes infrared laser conversion efficiency higher, and output power is larger, and stability is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared laser technology, and proposes a multi-wavelength infrared laser output device. BACKGROUND

[0002] Infrared laser has a wide range of applications in medical treatment, communication and scientific research fields. At present, the tunable infrared output generally adopts optical parametric oscillator (OPO), quantum cascade laser (QCL), tunable diode laser, difference frequency generation (DFG) and free electron laser (FEL), etc. These schemes realize the tuning of the infrared band through different mechanisms to meet various application requirements. Among them, the optical parametric oscillator (OPO) utilizes the parametric down-conversion of the nonlinear crystal and the feedback of the resonant cavity to generate tunable coherent light for efficient output. In a general OPO, at least one nonlinear crystal and two cavity mirrors are included. Pump light passes through the OPO and can only output tunable signal light and idler light in a specific wavelength range designed by the crystal. If a wider range of tunable infrared laser output is required, the commonly used method is "multi-stage cascade", that is, the pump light is incident into different OPO cavities after being split, each OPO cavity has a corresponding nonlinear crystal and a cavity mirror with corresponding film layers, and the wavelength port of the final output is switched to realize the output of signal light or idler light that can be continuously tuned within a certain wavelength range, as shown in Figure 1 In short, it is a pump light source, multiple OPOs form an OPO set, and the corresponding OPO outputs the required wavelength range, and other light is blocked from output.

[0003] The multi-stage cascade method for generating a wider range of lasers has the disadvantages of large device size, repeated equipment, high power requirement for the pump light source, and high overall equipment cost. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present application is to propose a multi-wavelength infrared laser output device that integrates multiple OPOs into one optical path.

[0005] The technical scheme of the present application is as follows:

[0006] The application discloses a multi-wavelength infrared laser output device, which comprises a nonlinear crystal with a displacement function, two triangular prisms and at least four cavity mirrors.

[0007] The nonlinear crystal comprises at least two different polarization periods, and the nonlinear crystal can be moved to a working position by adjusting the position of the nonlinear crystal.

[0008] The nonlinear crystal is a PPMgOLN crystal with a size of 50*10.2*1 mm 3 When the device works at a period of 31.5 µm, signal light output in a range of 1.7-1.9 µm can be obtained at different temperatures; when the device works at a period of 29.5 µm, idler light output in a range of 3.4-3.8 µm can be obtained at different temperatures.

[0009] The one kind of multi-wavelength infrared laser output device, when 1064nm pump light is vertically incident into the position of the period of nonlinear crystal Λ=31.5 µm after passing through the first three prism, first signal light and first idler light are generated, the wavelength interval of first signal light is in the range of 1.7~1.9µm, and the wavelength interval of first idler light is in the range of 2.4~2.8µm;Pump light and first idler light are directly output, first signal light is partially reflected by the first output mirror, passes through nonlinear crystal and two three prisms, reaches the first full reflection mirror, is fully reflected, and forms oscillation amplification in the cavity;The film layer of the first output mirror is R=65%@1.7~1.9µm;The film layer of the first full reflection mirror is HR@1.7~1.9µm (R>99%);The position of nonlinear crystal is moved, so that when the nonlinear crystal works at the position of the period Λ=29.5 µm, when 1064nm pump light is vertically incident into the position of the nonlinear crystal after passing through the first three prism, second signal light and second idler light are generated, the wavelength interval of second signal light is in the range of 1.4~1.5µm, and the wavelength interval of second idler light is in the range of 3.4~3.8µm;Pump light and second signal light are directly output, second idler light is partially reflected by the second output mirror, passes through nonlinear crystal and two three prisms, reaches the second full reflection mirror, is fully reflected, and forms oscillation amplification in the cavity;The film layer of the second output mirror is R=65%@3.4~3.8µm;The film layer of the second full reflection mirror is HR@3.4~3.8µm, R>99%;At this time, the pump light 1064nm passes through OPO, and four kinds of new wavelength outputs are obtained, which are 1.7~1.9µm, 2.4~2.8µm under the first crystal period, 1.4~1.5µm, 3.4~3.8µm under the second crystal period.

[0010] The one kind of multi-wavelength infrared laser output device, greater than two cavity mirrors are located at the left side of the first three prism, and greater than two cavity mirrors are located at the right side of the second three prism.

[0011] The beneficial effects of the present application are as follows:

[0012] The three limiting factors of multi-wavelength infrared laser output are the period of nonlinear crystal, the coating of cavity mirror, and the intensity of pump light. The present application realizes tunable multi-wavelength infrared laser output by moving the nonlinear crystal in the resonant cavity and the specific cavity mirror coating method of three prism beam splitting, and because the pump light does not need to be split, the infrared laser conversion efficiency is higher, and the output power is larger;Because the specific cavity mirror coating layer is relatively single, the damage threshold is high, so that the output stability of the laser is higher.

[0013] The output mirror of the traditional OPO needs to be coated with at least signal light transmission film, signal light reflection film, idler light transmission film and pump light transmission film, so that four different films need to be coated on one mirror. The film layer is not only difficult to coat but also has poor stability and is easy to damage the film layer. The present application can only coat two layers of film (signal light transmission film and signal light reflection film); the other end of the input mirror also has the same principle, and one layer of pump light transmission film is saved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a traditional OPO multi-stage cascade.

[0015] Figure 2 It is a nonlinear crystal moving to another polarization period position.

[0016] Figure 3 It is the principle of an optical parametric oscillator (OPO) commonly used in the prior art.

[0017] Figure 4 It is a structural schematic diagram of the present application.

[0018] In the figure, the first three prism 1, the second three prism 2, the first total reflection mirror 3, the second total reflection mirror 4, the first output mirror 5, the second output mirror 6, the nonlinear crystal 7. DETAILED DESCRIPTION

[0019] The present application will be further described below in combination with the drawings.

[0020] The principle of an optical parametric oscillator (OPO) commonly used in the prior art is shown in Figure 3 An oscillator includes a nonlinear crystal and two cavity mirrors, one of which is a total reflection mirror that transmits pump light, reflects signal light and idler light. At least three film layers need to be coated; the other output cavity mirror is usually coated with a film having a transmission rate of 20-90%, which can be signal light or idler light. The signal light or idler light is partially reflected back into the resonant cavity to oscillate and amplify, and the other beam that does not need to oscillate is coated with an anti-reflection film for pump light. This mirror also needs to be coated with three different film layers. In this way, an OPO can realize pump light input, conversion through a nonlinear crystal and oscillation and amplification in the cavity to output signal light and idler light.

[0021] The principle of an optical parametric oscillator designed by the present application is shown in Figure 4 An oscillator includes a nonlinear crystal 7, two three prisms and four cavity mirrors. The nonlinear crystal 7 is designed as Figure 2As shown, the nonlinear crystal 7 is moved to the operative position by adjusting the position of the nonlinear crystal 7, such as laterally moving the nonlinear crystal 7. For example, in one example of the present application, the nonlinear crystal 7 is a PPMgOLN crystal having dimensions of 50 x 10.2 x 1 mm 3, When the crystal works in the period Λ=31.5 µm position, the signal light output in the range of 1.7~1.9 µm can be obtained with different temperatures; when the crystal works in the period Λ=29.5 µm position, the idler light output in the range of 3.4~3.8 µm can be obtained with different temperatures. The first three-prism 1, the second three-prism 2, the first total reflection mirror 3, the second total reflection mirror 4, the first output mirror 5 and the second output mirror 6 together form an oscillation cavity. The three-prism realizes the dispersion effect by using the different refractive indexes of different wavelengths. The total reflection mirror and the output mirror are accurately placed according to the wavelength position of the three-prism dispersion to play the resonance effect. When the 1064nm pump light passes through the first three-prism 1 and is vertically incident into the period Λ=31.5 µm position of the nonlinear crystal 7, the first signal light and the first idler light are generated due to the nonlinear effect, the wavelength range of the first signal light is 1.7~1.9 µm, and the wavelength range of the first idler light is 2.4~2.8 µm. The pump light and the first idler light are directly output, the first signal light is partially reflected by the first output mirror 5, passes through the nonlinear crystal 7 and the two three-prisms, is totally reflected by the first total reflection mirror 3, and forms oscillation amplification in the cavity to improve the overall conversion efficiency of the OPO. The film layer of the first output mirror 5 is R=65%@1.7~1.9 µm; the film layer of the first total reflection mirror 3 is HR@1.7~1.9 µm (R>99%). When the crystal position is moved so that the crystal works in the period Λ=29.5 µm position, when the 1064nm pump light passes through the first three-prism 1 and is vertically incident into the position of the nonlinear crystal 7, the second signal light and the second idler light are generated due to the nonlinear effect, the wavelength range of the second signal light is 1.4~1.5 µm, and the wavelength range of the second idler light is 3.4~3.8 µm. The pump light and the second signal light are directly output, the second idler light is partially reflected by the second output mirror 6, passes through the nonlinear crystal 7 and the two three-prisms, is totally reflected by the second total reflection mirror 4, and forms oscillation amplification in the cavity to improve the overall conversion efficiency of the OPO. The film layer of the second output mirror 6 is R=65%@3.4~3.8 µm; the film layer of the second total reflection mirror 4 is HR@3.4~3.8 µm (R>99%). Thus, the pump light 1064nm passes through the OPO, and four kinds of output wavelengths can be obtained, which are 1.7~1.9 µm, 2.4~2.8 µm under the first crystal period, 1.4~1.5 µm, 3.4~3.8 µm under the second crystal period, which spans the wide infrared laser output range of 1.4um to 3.8um. By analogy, if the nonlinear crystal 7 has several periods, and corresponding reflection mirrors and output mirrors are arranged according to the refractive index, more wavelengths can be obtained. After the above wavelength output, the output or blocking is selected according to the actual demand, which is not described here.In the optical path, the pump light can also be selected not to be all output, but all reflected or partially reflected back to the OPO to continue pumping. This optical path is only a complex version of the foregoing optical path, which will not be described here.

[0022] The technical features of the above-described embodiments can be further combined. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the description. The scope of protection of the present application is given by the appended claims and any equivalents thereof.

Claims

1. A multi-wavelength infrared laser output device, characterized by, The application relates to a multi-wavelength infrared laser output device, which comprises a nonlinear crystal (7) with a displacement function, two triangular prisms and at least four cavity mirrors. The nonlinear crystal (7) is located in the middle of the two triangular prisms, part of the cavity mirrors are located on the left side of a first triangular prism (1), and the rest of the cavity mirrors are located on the right side of a second triangular prism (2); pump light is incident on the nonlinear crystal (7) through the first triangular prism (1), and first signal light and first idler light are generated; the pump light, the first signal light and the first idler light pass through the second triangular prism (2) and are dispersed into three light paths, wherein the first signal light is blocked by a first output mirror (5) and is reflected back to part of the light beams to pass through the two triangular prisms, the nonlinear crystal (7) and a first total reflection mirror (3) again, and is totally reflected back to be amplified in the cavity, and the pump light and the first idler light are completely output; at this time, the infrared laser output can select two wavelengths or one, which are the first signal light and the first idler light respectively; the position of the nonlinear crystal (7) is adjusted, the nonlinear crystal (7) is moved to another polarization period position, pump light is incident on the nonlinear crystal (7) through the first triangular prism (1), second signal light and second idler light are generated, and the pump light passes through the second triangular prism (2) after the nonlinear crystal (7) and is dispersed into three light paths; wherein only the second idler light is blocked by a second output mirror (6) and is reflected back to part of the light beams to pass through the two triangular prisms, the nonlinear crystal (7) and a second total reflection mirror (4) again, and is totally reflected back to be amplified in the cavity, and the pump light and the second signal light are completely output; at this time, the infrared laser output can select two wavelengths or one, which are the second signal light and the second idler light respectively.

2. A multi-wavelength infrared laser output device according to claim 1, wherein The nonlinear crystal (7) comprises at least two different polarization periods, and the position of the nonlinear crystal (7) can be adjusted to move the nonlinear crystal (7) to a working position.

3. The multi-wavelength infrared laser output device according to claim 1 or 2, characterized in that the nonlinear crystal (7) comprises at least two different polarization periods. The nonlinear crystal (7) is PPMgOLN crystal with a size of 50*10.2*1 mm 3 , When working at the position of period Lambda=31.5 microns, the signal light output in the range of 1.7-1.9 microns can be obtained with different temperatures; when working at the position of period Lambda=29.5 microns, the idler light output in the range of 3.4-3.8 microns can be obtained with different temperatures.

4. The multi-wavelength infrared laser output device according to claim 2, characterized in that the nonlinear crystal (7) comprises at least two different polarization periods. When the 1064nm pump light passes through the first three-prism (1) and is vertically incident into the nonlinear crystal (7) at the position of period Λ=31.5 µm, the first signal light and the first idler light are generated, the wavelength range of the first signal light is 1.7~1.9 µm, and the wavelength range of the first idler light is 2.4~2.8 µm; the pump light and the first idler light are directly output, the first signal light is partially reflected by the first output mirror (5), passes through the nonlinear crystal (7) and the two three-prisms, reaches the first full reflection mirror (3), is fully reflected, and forms oscillation amplification in the cavity; the film layer of the first output mirror (5) is R=65%@1.7~1.9 µm; the film layer of the first full reflection mirror (3) is HR@1.7~1.9 µm (R>99%); the position of the nonlinear crystal (7) is moved, so that when the nonlinear crystal (7) works at the position of period Λ=29.5 µm, when the 1064nm pump light passes through the first three-prism (1) and is vertically incident into the nonlinear crystal (7) at this position, the second signal light and the second idler light are generated, the wavelength range of the second signal light is 1.4~1.5 µm, and the wavelength range of the second idler light is 3.4~3.8 µm; the pump light and the second signal light are directly output, the second idler light is partially reflected by the second output mirror (6), passes through the nonlinear crystal (7) and the two three-prisms, reaches the second full reflection mirror (4), is fully reflected, and forms oscillation amplification in the cavity; the film layer of the second output mirror (6) is R=65%@3.4~3.8 µm; the film layer of the second full reflection mirror (4) is HR@3.4~3.8 µm, R>99%; at this time, the pump light 1064nm passes through the OPO, and four new wavelengths of output are obtained, which are 1.7~1.9 µm, 2.4~2.8 µm under the first crystal period, 1.4~1.5 µm, 3.4~3.8 µm under the second crystal period.

5. The multi-wavelength infrared laser output device of claim 1, wherein, The larger two-mirror cavity is located on the left side of the first three-prism (1), and the larger two-mirror cavity is located on the right side of the second three-prism (2).

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