A dual-band near-infrared pulsed laser

Abstract

The application discloses a kind of dual-band near-infrared pulse lasers, belong to laser technical field, including pump source, coupling optical system, pump light module, pulse light module, light parametric oscillation module and output mirror.Pump source is connected coupling optical system, pump light module, pulse light module, light parametric oscillation module and output mirror in sequence.The 443nm laser generated by pump source is under the action of coupling optical system and pump light module to output pump light, under the action of output mirror to generate 522nm fundamental frequency laser, under the action of pulse light module to output 522nm pulse laser, under the action of light parametric oscillation module to output 800nm and 1502nm laser to output mirror, and output to cavity outside via output mirror to form near-infrared band dual-band laser output.The dual-band near-infrared pulse laser of the application simplifies light-light conversion process, thereby reducing device unit, so that laser is smaller and lighter in weight.Meanwhile, the light-light conversion efficiency of the dual-band near-infrared pulse laser of the application is higher.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser, and particularly relates to a dual-band near-infrared pulsed laser. BACKGROUND

[0002] In the field of laser ranging and laser imaging, multi-wavelength lasers are often used as illumination light sources to improve ranging accuracy and imaging resolution. At present, semiconductor laser light sources near 800nm-900nm and erbium-ytterbium co-doped laser light sources near 1500nm-1600nm are relatively mature, and they are atmospheric windows, so it is common to use 800nm-900nm and 1500nm-1600nm lasers as illumination light sources.

[0003] At present, the way to obtain 800nm-900nm and 1500nm-1600nm lasers is to generate 532nm by frequency doubling of 1064nm laser, and then use it as pump light to obtain 800nm near signal light and 1600nm near idler light by optical parametric oscillation.

[0004] However, the current technology for obtaining this dual-band near-infrared laser has some deficiencies: (1) complex structure and poor stability, the technical process contained in the commonly used technology is relatively complex, and the final required laser needs to be converted several times, and each technical process needs to be accurately adjusted, so the stability is poor. (2) Large volume, each technical process in the commonly used technology needs a certain volume space, and the final formed laser does not have the advantages of volume and weight. (3) Low optical conversion efficiency, due to multiple light conversion processes in the commonly used technology, the optical conversion efficiency is usually 1%-3%, and high optical conversion efficiency cannot be obtained. SUMMARY

[0005] In view of one or more of the above defects or improvement needs of the prior art, the application provides a dual-band near-infrared pulsed laser, which comprises a pump source for generating 443nm laser, and further comprises a coupling optical system, a pump light module, a pulsed light module, an optical parametric oscillation module and an output mirror.

[0006] The pump light module comprises a laser gain medium, and the laser gain medium is a praseodymium-doped yttrium lithium fluoride (Pr:YLF) laser crystal.

[0007] The optical parametric oscillation module comprises a nonlinear optical crystal, and the nonlinear optical crystal is a lithium triborate (LBO) crystal.

[0008] The pump source is sequentially connected with the coupling optical system, the pump light module, the pulse light module, the optical parametric oscillation module and the output mirror; the 443nm laser generated by the pump source is outputted as pump light under the action of the coupling optical system and the pump light module, is transmitted to the output mirror, generates 522nm base frequency laser under the action of the output mirror, is transmitted to the pulse light module, is outputted as 522nm pulse laser under the action of the pulse light module, is transmitted to the optical parametric oscillation module, is outputted as 800nm and 1502nm laser to the output mirror under the action of the optical parametric oscillation module, and is outputted to outside of the cavity via the output mirror to form near-infrared waveband double waveband laser output.

[0009] As a further improvement of the present application, the coupling optical system is a coupling lens.

[0010] As a further improvement of the present application, the coupling lens is coated with an anti-reflection film.

[0011] As a further improvement of the present application, the pump light module further comprises a first input mirror, and the output end of the first input mirror is connected with the input end of the laser gain medium.

[0012] As a further improvement of the present application, the first input mirror is specifically an optical lens with high transmittance to pump light and high reflectivity to base frequency light, and is coated with an anti-reflection film.

[0013] As a further improvement of the present application, the pulse light module comprises a signal generator and an acousto-optic Q-switch crystal, and the output end of the signal generator is connected with the input end of the acousto-optic Q-switch crystal.

[0014] As a further improvement of the present application, the signal generator provides a periodic pulse square wave signal for the acousto-optic Q-switch crystal, and the acousto-optic Q-switch crystal is an optical crystal with variable cavity loss corresponding to the intensity of ultrasonic field.

[0015] As a further improvement of the present application, the optical parametric oscillation module further comprises a second input mirror, and the output end of the second input mirror is connected with the input end of the nonlinear optical crystal.

[0016] As a further improvement of the present application, the second input mirror is specifically an optical lens with high transmittance to pump light and base frequency light and high reflectivity to signal light and idler light, and is coated with an anti-reflection film.

[0017] As a further improvement of the present application, the pump source is a semiconductor laser; and / or

[0018] The output mirror is an optical lens with high reflectivity to pump light and base frequency light, specific reflectivity to signal light and high transmittance to idler light, and is coated with an anti-reflection film.

[0019] The above technical features can be combined with each other as long as they do not conflict with each other.

[0020] In general, compared with the prior art, the above technical solutions conceived by the present application have the beneficial effects including:

[0021] (1) The dual-band near-infrared pulse laser of the present application can simplify the light-light conversion process through the pump light module and the optical parametric oscillation module, thereby reducing the device units, making the dual-band near-infrared pulse laser of the present application smaller and lighter in weight. At the same time, the light-light conversion rate between each module of the dual-band near-infrared pulse laser of the present application is high, making the final light-light conversion efficiency also high.

[0022] (2) The dual-band near-infrared pulse laser of the present application, by coating the required devices, makes the efficiency of specific laser in the light conversion process higher through these components, and the utilization rate of light is higher, ensuring the reliability of the entire light conversion process and having a high conversion efficiency, and at the same time making the overall stability of the device better.

[0023] (3) The dual-band near-infrared pulse laser of the present application, by using specific materials or components for some optical devices, can improve the overall light-light conversion efficiency, and also enhance the stability and achieve structural simplification, which is helpful for the realization of miniaturization and light weight, and has good application value.

[0024] (4) The dual-band near-infrared pulse laser of the present application adopts the mode of praseodymium-doped laser and intracavity optical parametric oscillation (OPO), which can simplify the light-light conversion process (443nm→522nm→800nm+1502nm), achieve the effects of structural simplification and stability enhancement. Further, the dual-band near-infrared pulse laser of the present application can also simplify the system composition and units, which is helpful for the realization of miniaturization and light weight, and due to the high light-light conversion efficiency between each module, it ensures the improvement of the final light-light conversion efficiency (expected to reach 15%-20%). The dual-band near-infrared pulse laser of the present application has a simple overall structure and high efficiency, and has good application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 is the overall structure schematic diagram of the dual-band near-infrared pulse laser in the embodiments of the present application;

[0027] In all the drawings, the same reference signs refer to the same technical features, specifically:

[0028] 1, pump source; 2, coupling optical system; 3, pump light module; 4, pulse light module; 5, optical parametric oscillation module; 6, output mirror;

[0029] 301, first input mirror; 302, laser gain medium;

[0030] 401, signal generator; 402, acousto-optic Q-switch crystal;

[0031] 501, second input mirror; 502, nonlinear optical crystal. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0033] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0035] In the present application, unless otherwise clearly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements or interaction relationship between two elements, unless otherwise clearly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise clearly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0037] Embodiment:

[0038] Please refer to Figure 1 The dual-band near-infrared pulse laser in the preferred embodiment of the present application comprises a pump source 1, a coupling optical system 2, a pump light module 3, a pulse light module 4, an optical parametric oscillation module 5 and an output mirror 6. As shown in Figure 1 The output end of the pump source 1 is connected to the input end of the coupling optical system 2, the output end of the coupling optical system 2 is connected to the input end of the pump light module 3, the output end of the pump light module 3 is connected to the input end of the pulse light module 4, the output end of the pulse light module 4 is connected to the input end of the optical parametric oscillation module 5, and the output end of the optical parametric oscillation module 5 is connected to the output mirror 6.

[0039] Further, the pump source 1 in the preferred embodiment is a semiconductor laser and can generate 443nm blue laser. The output mirror 6 is an optical mirror with high reflectivity to pump light and fundamental light, specific reflectivity to signal light and high transmittance to idle frequency light, which is further coated with an antireflection film to make its reflectivity to 522nm laser higher and its transmittance to 800nm and 1502nm laser higher.

[0040] Specifically, in the preferred embodiment, the pump source 1 is connected to the input end of the coupling optical system 2, wherein the coupling optical system 2 is preferably a coupling lens, and is coated with an antireflection film to increase the transmittance to 443nm laser. When the pump source 1 generates 443nm blue laser, it can enter the coupling optical system 2 for coupling. Moreover, the output end of the coupling optical system 2 is connected to the input end of the pump light module 3.

[0041] In detail, the pump light module 3 in the preferred embodiment comprises a first input mirror 301 and a laser gain medium 302, the output end of the coupling optical system 2 is connected to the input end of the first input mirror 301 at this time, and the output end of the first input mirror 301 is connected to the input end of the laser gain medium 302. In the preferred embodiment, the first input mirror 301 is an optical mirror with high transmittance to the pump light and high reflectivity to the fundamental light. Further, the first input mirror 301 is coated with an anti-reflection film to improve the transmittance to the 443 nm laser and the reflectivity to the 522 nm laser. Preferably, the pump source 1 generates pump laser to excite the laser gain medium 302. In the preferred embodiment, the laser gain medium 302 is a Pr:YLF laser crystal.

[0042] It can be understood that the 443 nm laser generated by the pump source 1 is transmitted to the first input mirror 301 through the coupling optical system 2, and then transmitted to the laser gain medium 302 through the first input mirror 301 for optical power amplification.

[0043] Further, in the preferred embodiment, the output pump light of the pump light module 3 passes through the pulsed light module 4 and the optical parametric oscillation module 5 to the output mirror 6, and the laser after passing through the pump light module 3 does not react in the pulsed light module 4 and the optical parametric oscillation module 5, i.e. the pump light output by the laser gain medium 302 reaches the output mirror 6, and the 522 nm fundamental light is generated by the output mirror 6 to the pulsed light module 4. The 522 nm fundamental light generated by the output mirror 6 only reacts in the pulsed light module 4, so the 522 nm fundamental light generated by the output mirror 6 will enter the pulsed light module 4 to react.

[0044] More specifically, in the preferred embodiment, the pulsed light module 4 comprises a signal generator 401 and an acousto-optic Q-switch crystal 402, and the output end of the signal generator 401 is connected to the input end of the acousto-optic Q-switch crystal 402. In the preferred embodiment, the signal generator 401 provides a periodic pulsed square wave signal to the acousto-optic Q-switch crystal 402, and the acousto-optic Q-switch crystal 402 is an optical crystal that changes the intracavity loss corresponding to the ultrasonic field intensity.

[0045] It can be understood that the 522 nm fundamental light output by the output mirror 6 is transmitted to the input end of the acousto-optic Q-switch crystal 402, and since the signal generator 401 provides a periodic pulsed square wave signal to the acousto-optic Q-switch crystal 402, the 522 nm fundamental light is output as 522 nm pulsed light after passing through the acousto-optic Q-switch crystal 402.

[0046] In more detail, the light parametric oscillation module 5 in the preferred embodiment comprises a second input mirror 501 and a nonlinear optical crystal 502, and the output end of the second input mirror 501 is connected to the input end of the nonlinear optical crystal 502. In the preferred embodiment, the second input mirror 501 is an optical mirror with high transmittance for pump light and fundamental light and high reflectivity for signal light and idler light, which is preferably coated with an antireflection film to improve the transmittance for 522 nm laser and the reflectivity for 800 nm and 1502 nm laser. The nonlinear optical crystal 502 is preferably a lithium triborate (LBO) crystal. The selection of the specific materials of some components improves the light-light conversion rate between the modules.

[0047] It can be understood that the 522 nm pulsed laser output by the pulsed light module 4 is input to the input end of the second input mirror 501 of the light parametric oscillation module 5, and the 800 nm and 1502 nm lasers output by the light parametric oscillation of the second input mirror 501 and the nonlinear optical crystal 502 are output to the output mirror 6 and then to the outside of the cavity to form a near-infrared dual-band laser output. The device adopts an intra-cavity optical parametric oscillation (OPO) mode, effectively simplifying the light-light conversion process and further simplifying the overall structure of the device and making it more reliable. In the above light-light conversion process, the light-light conversion efficiency between the modules is high, so the overall light-light conversion efficiency of the laser is also high.

[0048] The working process of the dual-band near-infrared pulsed laser of the present application is as follows: first, the semiconductor laser generates 443 nm blue laser, which enters the praseodymium-doped yttrium lithium fluoride (Pr:YLF) laser crystal for pumping through the coupling lens coated with a film with high transmittance for 443 nm and the first input mirror coated with a film with high transmittance for 443 nm and high reflectivity for 522 nm, and generates 522 nm fundamental frequency laser under the action of the output mirror 6 coated with a film with high reflectivity for 522 nm and high transmittance for 800 nm and 1502 nm. Then, the 522 nm pulsed laser becomes a pulsed laser under the action of the signal generator 401 and the acousto-optic Q-switch crystal 402, enters the lithium triborate crystal through the second input mirror 501 coated with a film with high transmittance for 522 nm and high reflectivity for 800 nm and 1502 nm, generates 800 nm and 1502 nm laser under the action of optical parametric oscillation, and is finally output to the outside of the cavity through the output mirror 6 to form a near-infrared dual-band laser output.

[0049] The double-band near-infrared pulse laser in the application adopts a mode of Pr-doped laser and intracavity optical parametric oscillation (OPO), so that the light-light conversion process (443nm→522nm→800nm+1502nm) can be simplified, the structure is simplified, and the stability is enhanced. Further, the double-band near-infrared pulse laser can also simplify the system composition and units, which is helpful to realize miniaturization and light weight, and due to the high light-light conversion efficiency between the modules, the final light-light conversion efficiency is ensured to be improved (expected to reach 15%-20%). The double-band near-infrared pulse laser has simple overall structure and high efficiency, and has good application prospect.

[0050] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual band near infrared pulsed laser comprising a pump source generating 443 nm laser, characterized in that, The coupling optical system, the pump light module, the pulse light module, the optical parametric oscillation module and the output mirror are further included. The pump light module comprises a laser gain medium, which is a praseodymium-doped yttrium lithium fluoride (Pr:YLF) laser crystal. The optical parametric oscillation module comprises a nonlinear optical crystal, which is a lithium triborate (LBO) crystal. The pump source is sequentially connected with the coupling optical system, the pump light module, the pulse light module, the optical parametric oscillation module and the output mirror. The 443 nm laser generated by the pump source is output as pump light under the action of the coupling optical system and the pump light module, and is transmitted to the output mirror. The 522 nm fundamental frequency laser is generated under the action of the output mirror, and is transmitted to the pulse light module. The 522 nm pulse laser is output under the action of the pulse light module, and is transmitted to the optical parametric oscillation module. The 800 nm and 1502 nm lasers are output under the action of the optical parametric oscillation module to the output mirror, and are output to the outside of the cavity via the output mirror to form a near-infrared waveband dual-waveband laser output.

2. The dual-band near-infrared pulsed laser of claim 1, wherein, The coupling optical system is a coupling lens.

3. The dual-band near-infrared pulsed laser of claim 2, wherein, The coupling lens is coated with an anti-reflection film.

4. The dual-band near-infrared pulsed laser of claim 1, wherein, The pump light module further comprises a first input mirror, and an output end of the first input mirror is connected with an input end of the laser gain medium.

5. The dual-band near-infrared pulsed laser of claim 4, wherein, The first input mirror is specifically an optical lens with high transmittance to pump light and high reflectivity to fundamental frequency light, and an anti-reflection film is coated on the first input mirror.

6. The dual-band near-infrared pulsed laser of claim 1, wherein, The pulse light module comprises a signal generator and an acousto-optic Q-switching crystal, and an output end of the signal generator is connected with an input end of the acousto-optic Q-switching crystal.

7. The dual-band near-infrared pulsed laser of claim 6, wherein, The signal generator provides a periodic pulse square wave signal for the acousto-optic Q-switching crystal, and the acousto-optic Q-switching crystal is an optical crystal corresponding to the change of intracavity loss caused by the change of ultrasonic field intensity.

8. The dual-band near-infrared pulsed laser of claim 1, wherein, The optical parametric oscillation module further comprises a second input mirror, and an output end of the second input mirror is connected with an input end of the nonlinear optical crystal.

9. The dual-band near-infrared pulsed laser of claim 8, wherein, The second input mirror is specifically an optical lens with high transmittance to pump light and fundamental frequency light and high reflectivity to signal light and idler light, and an anti-reflection film is coated on the second input mirror.

10. The dual-band near-infrared pulsed laser of any one of claims 1-9, wherein, The pump source is a semiconductor laser; and / or The output mirror is an optical lens with high reflectivity to pump light and fundamental frequency light, specific reflectivity to signal light and high transmittance to idler light, and an anti-reflection film is coated on the output mirror.

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