Monolithic Microchip Lasers

Abstract

The present invention provides a monolithic microchip laser, comprising: a pump source for emitting a pump light with a wavelength of 808nm; a gain medium at least comprising a top surface, a first side surface and a second side surface respectively connected to the top surface, the first side surface and the second side surface respectively being arranged at an acute angle with the top surface; a two-color film and a 1064nm partial reflection film, the two-color film being arranged on the top surface and close to the pump source, the 1064nm partial reflection film being arranged on the top surface and away from one side of the pump source; a first Q-switched crystal and a second Q-switched crystal, respectively arranged on the first side surface and the second side surface, the first Q-switched crystal and the second Q-switched crystal being used to generate Q-switched pulses. In the above manner, the present invention can improve the average power and beam quality of the laser emitted by the monolithic microchip laser.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and in particular to a single-chip microchip laser. Background Art

[0002] Monolithic microchip lasers generally include a resonant cavity, a Q-switched device, and a laser gain crystal. They have the advantages of small size, high beam quality, and narrow pulse width. They are mainly used in laser imaging, industrial processing, biomedicine, and military detection.

[0003] Current microchip lasers require both a small size and excellent output laser power. For the output pulses, a laser of a certain wavelength is generally oscillated through a resonant cavity to form a pulsed laser of another wavelength. However, the existing laser resonant cavities have a single shape, which is formed between a Q-switched crystal and a gain medium. As a result, the laser propagation distance in the resonant cavity is too short and is limited by the shape of the crystal. As a result, the output laser power and quality are average, and the stability of the output laser is not high. Summary of the invention

[0004] The embodiment of the present invention provides a monolithic microchip laser to solve the technical problem of the general quality of the pulsed laser output by the laser in the prior art.

[0005] An embodiment of the present invention provides a monolithic microchip laser, comprising:

[0006] A pump source, used for emitting pump light with a wavelength of 808 nm;

[0007] A gain medium, the gain medium comprising at least a top surface, a first side surface and a second side surface respectively connected to the top surface, the first side surface and the second side surface respectively being arranged at an acute angle to the top surface;

[0008] A two-color film and a 1064nm partial reflection film, wherein the two-color film is arranged on the top surface and close to the pump source, and the 1064nm partial reflection film is arranged on the top surface and away from the pump source;

[0009] A first Q-switched crystal and a second Q-switched crystal are respectively arranged on the first side and the second side, and the first Q-switched crystal and the second Q-switched crystal are used to generate Q-switched pulses; wherein,

[0010] A laser resonant cavity is formed between the two-color film, the 1064nm partial reflection film, the first Q-switched crystal and the second Q-switched crystal. The 808nm pump light emitted by the pump source is reflected at least twice in the laser resonant cavity, and a laser with a wavelength of 1064nm is formed under the action of the gain medium. Then, the laser with a wavelength of 1064nm oscillates in the laser resonant cavity, and a Q-switched effect is generated by the first Q-switched crystal and the second Q-switched crystal to form a pulsed laser with a wavelength of 1064nm. Then, the pulsed laser with a wavelength of 1064nm is output in the form of pulses at the 1064nm partial reflection film.

[0011] According to the monolithic microchip laser of one embodiment of the present invention, the first Q-switched crystal and the second Q-switched crystal are both made of two-dimensional nanomaterials, and the two-dimensional nanomaterials are graphene or molybdenum disulfide.

[0012] According to the monolithic microchip laser of one embodiment of the present invention, the first Q-switched crystal and the second Q-switched crystal are respectively detachably connected to the gain medium.

[0013] According to a monolithic microchip laser of one embodiment of the present invention, the first Q-switched crystal and the second Q-switched crystal are prepared on the surface of the gain medium by chemical transfer, and the first Q-switched crystal and the second Q-switched crystal can be disassembled by chemical transfer.

[0014] According to a monolithic microchip laser of one embodiment of the present invention, a pump collimating and focusing lens group is provided downstream of the pump source, and the pump collimating and focusing lens group is used to receive the pump light emitted by the pump source, collimate and focus the pump light, and inject the pump light into the gain medium through the dichroic film.

[0015] According to a monolithic microchip laser of one embodiment of the present invention, the angle between the first Q-switched crystal and the top surface is the same as the angle between the second Q-switched crystal and the top surface, so that the direction of light received by the first Q-switched crystal is set parallel to the direction of light emitted by the second Q-switched crystal.

[0016] According to a monolithic microchip laser of one embodiment of the present invention, the gain medium is Nd 3+ :YVO4 crystal or Nd 3+ :GdVO4 crystal.

[0017] According to a monolithic microchip laser of one embodiment of the present invention,

[0018] The two-color film fully reflects light waves with a wavelength of 1064nm and fully transmits light waves with a wavelength of 808nm;

[0019] The 1064nm partial reflection film partially reflects light waves with a wavelength of 1064nm, and fully reflects light waves with a wavelength of 808nm.

[0020] According to the monolithic microchip laser of one embodiment of the present invention, the gain medium further comprises a bottom surface, the bottom surface is arranged parallel to the top surface, and the bottom surface is connected to the first side surface and the second side surface respectively.

[0021] According to a monolithic microchip laser of one embodiment of the present invention, the gain medium further comprises at least one third side surface, the angle between the third side surface and the top surface is smaller than the angle between the first side surface or the second side surface and the top surface, and the third side surface is connected to the first side surface and the second side surface respectively, and the pump light emitted by the pump source is reflected on the first side surface, the second side surface and the third side surface in sequence.

[0022] The monolithic microchip laser provided by an embodiment of the present invention comprises a top surface, a bottom surface, a first side surface and a second side surface, and a first Q-switched crystal and a second Q-switched crystal are provided on the first side surface and the second side surface, and the pump light emitted by the pump source passes through the dichroic film provided on the top surface, the first Q-switched crystal and the second Q-switched crystal in sequence and is emitted from the 1064nm partial reflection film, because a resonant cavity is formed between the first Q-switched crystal, the second Q-switched crystal, the dichroic film and the 1064nm partial reflection film, and the laser is reflected at least twice in the laser resonant cavity, thereby making the average power and beam quality of the pulsed laser emitted through the resonant cavity higher and the stability better. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of an embodiment of a monolithic microchip laser of the present invention;

[0025] Figure 2 This is a structural test diagram of the first Q-switched crystal and the second Q-switched crystal of the present invention with different thicknesses for saturated absorption of light waves;

[0026] Figure 3 FIG. 4 is another schematic diagram of the cross-sectional structure of the gain medium of the present invention.

[0027] Reference numerals:

[0028] 10. Pump source;

[0029] 20, gain medium; 210, top surface; 220, bottom surface; 230, first side surface; 240, second side surface; 250, laser resonant cavity; 260, third side surface;

[0030] 30. Two-color film;

[0031] 40, 1064nm partial reflection film;

[0032] 50. Pump collimating and focusing lens assembly;

[0033] 60. The first Q-switched crystal;

[0034] 70. Second Q-switched crystal;

[0035] 80. test laser; 810. spectroscope; 820. converging lens; 840. aperture; 850. first energy meter; 860. second energy meter. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Please refer to Figure 1 , Figure 1The structure diagram of an embodiment of a monolithic microchip laser of the present invention. The present invention provides a monolithic micro-light laser, comprising a pump source 10, a gain medium 20, a two-color film 30, a 1064nm partial reflection film 40, a first Q-switched crystal 60 and a second Q-switched crystal 70. The pump source 10 is used to emit a pump light with a wavelength of 808nm. The gain medium 20 at least comprises a top surface 210, a first side surface 230 and a second side surface 240 respectively connected to the top surface 210, and the first side surface 230 and the second side surface 240 are respectively arranged at an acute angle with the top surface 210. The two-color film 30 is arranged on the top surface 210 and close to the pump source 10, and the 1064nm partial reflection film 40 is arranged on the top surface 210 and away from the pump source 10. The first Q-switched crystal 60 and the second Q-switched crystal 70 are respectively arranged on the first side surface 230 and the second side surface 240, and the first Q-switched crystal 60 and the second Q-switched crystal 70 are used to generate Q-switched pulses. Among them, a laser resonant cavity 250 is formed between the two-color film 30, the 1064nm partial reflection film 40, the first Q-switched crystal 60 and the second Q-switched crystal 70. The 808nm pump light emitted by the pump source 10 is reflected at least twice in the laser resonant cavity 250, and a laser with a wavelength of 1064nm is formed under the action of the gain medium 20. Then, the laser with a wavelength of 1064nm oscillates in the laser resonant cavity 250, and the first Q-switched crystal 60 and the second Q-switched crystal 70 produce a Q-switched effect to form a pulsed laser with a wavelength of 1064nm, and then the pulsed laser with a wavelength of 1064nm is output in the form of pulses at the 1064nm partial reflection film 40.

[0038] It should be noted that, because the dichroic film 30 can completely reflect the light waves with a wavelength of 1064nm and completely transmit the light waves with a wavelength of 808nm, that is, the 808nm pump light emitted by the pump source 10 can enter the laser resonant cavity 250 through the dichroic film 30, but when oscillating in the laser resonant cavity 250, the light waves with a wavelength of 1064nm cannot be emitted outward from one side of the dichroic film 30. After the 808nm light wave is absorbed by the gain medium 20, the number of particles in the gain medium 20 is reversed, gathered at the upper energy level and generates laser radiation. The first Q-switched crystal 60 and the second Q-switched crystal 70 arranged on the side of the gain medium 20 will initially absorb the laser radiation. When the first Q-switched crystal 60 and the second Q-switched crystal 70 are saturated with absorption, the upper energy level particles of the gain medium 20 quickly transition to the lower energy level, forming laser oscillation in the laser resonant cavity 250. The two-color film 30 arranged on the top surface 210 completely reflects the 1064nm light wave and cannot output it to the outside. The 1064nm partial reflection film 40 arranged on the top surface 210 can pass the 1064nm pulse laser, and then the 1064nm pulse laser can be output from this end.

[0039] In one embodiment of the present invention, the first Q-switching crystal 60 and the second Q-switching crystal 70 are both made of two-dimensional nanomaterials, and the two-dimensional nanomaterials are graphene or molybdenum disulfide. Preferably, graphene can be used as the two-dimensional nanomaterial, but in other embodiments, molybdenum disulfide can also be used, which is not limited here.

[0040] Specifically, the first Q-switching crystal 60 and the second Q-switching crystal 70 are detachably connected to the gain medium 20. The assembly of the Q-switching crystal is generally performed by assembly and curing through optical glue. In this way, once the Q-switching crystal and the gain medium 20 are assembled, the Q-switching crystal cannot be disassembled or thickened as the crystal grows, and thus the Q-switching performance of the Q-switching crystal cannot be changed.

[0041] In the present invention, the first Q-switched crystal 60 and the second Q-switched crystal 70 are prepared or disassembled on the gain medium 20 by chemical transfer. That is, the first Q-switched crystal 60 can be prepared on the surface of the gain medium 20 by chemical transfer. When a thicker first Q-switched crystal 60 or second Q-switched crystal 70 is needed, it can be disassembled by chemical transfer. Specifically, a graphene film can be grown on a metal base by chemical vapor deposition (CAD), and then polymethyl methacrylate (PMMA) is spin-coated on the graphene and forms a covalent bond with it. After the metal base is corroded, a PMMA / graphene layer can be obtained, and then the PMMA / graphene layer can be transferred to the target base, that is, the surface of the gain medium 20. The PMMA can be removed by acetone or the like, so that the graphene film and the laser crystal can be combined with the gain medium 20. When the graphene needs to be disassembled, epoxy bonding technology can be used to utilize the strong interaction between graphene and epoxy resin to mechanically peel off the graphene from the crystal substrate.

[0042] Please refer to Figure 2 , Figure 2 This is a structural test diagram of the saturated absorption light waves of different thicknesses of the first Q-switched crystal 60 and the second Q-switched crystal 70 of the present invention. The thicknesses selected for the first Q-switched crystal 60 and the second Q-switched crystal 70 can be tested by a scanning method, that is, for lasers of different wavelengths, a Q-switched crystal of suitable thickness can be selected by a scanning method. It should be noted that the thickness of the first Q-switched crystal 60 may be inconsistent with the thickness of the second Q-switched crystal 70. For example, a model of graphene and saturated absorption can be established, and then the regulation of the layer growth of two-dimensional nanomaterials can be studied, thereby optimizing the Q-switching performance. That is Figure 2In the embodiment, the test laser 80, the beam splitter 810, the convergence lens 820, the aperture 840, the first energy meter 850 and the second energy meter 860 are included. The laser emitted by the test laser 80 reaches the two-dimensional nanomaterial film through the beam splitter 810 and the convergence lens 820, which corresponds to A in the figure, the first Q-switched crystal 60 and the second Q-switched crystal 70, and the two-dimensional nanomaterial film such as graphene. Then, the laser passing through the two-dimensional nanomaterial film is measured by the first energy meter 850, and the laser reflected by the two-dimensional nanomaterial lens is measured by the second energy meter 860. Then, the amount of absorption of the two-dimensional nanomaterial film of different thicknesses can be obtained by subtracting the amount of the first energy meter 850 and the second energy meter 860 from the amount of the laser initially emitted. Because the first Q-switched crystal 60 and the second Q-switched crystal 70 are both detachable from the gain medium 20, when higher Q-switching performance is required, the corresponding thickness can be selected in advance and then replaced with the original Q-switched crystal. The terms "first", "second", and "third" in the present invention 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", "second", and "third" may explicitly or implicitly include at least one of the features.

[0043] Please continue to refer to Figure 1 , a pump collimating and focusing lens group 50 is provided downstream of the pump source 10, and the pump collimating and focusing lens group 50 is used to receive the pump light emitted by the pump source 10, collimate and focus the pump light, and then pass through the dichroic film 30 to enter the gain medium 20. That is, the pump light emitted by the pump source 10 will converge after passing through the pump collimating and focusing lens group 50, and then be transmitted to the dichroic film 30, and then pass through the dichroic film 30 to enter the gain medium 20.

[0044] The angle between the first Q-switched crystal 60 and the top surface 210 is the same as the angle between the second Q-switched crystal 70 and the top surface 210, so that the direction of the light received by the first Q-switched crystal 60 is arranged parallel to the light emitted by the second Q-switched crystal 70. In this way, the pump source 10 emitting the laser and the receiving element after the laser output can be arranged flush, which is convenient for receiving the output laser and can make the volume of the entire device smaller.

[0045] In one embodiment of the present invention, the gain medium 20 may be Nd 3+ :YVO4 crystal, Nd 3+ :GdVO4 crystal. Preferably, the present invention can use Nd 3+ :YVO4 crystal, because Nd 3+ :The stimulated emission cross section of YVO4 crystal at 1064nm is Nd 3+:YAG crystal is more than three times, and has more advantages under high frequency operation. It can be understood that in other embodiments, Nd 3+ :GdVO4 crystal, not limited here.

[0046] Because Nd 3+ :YAG gain medium 20 is usually designed as a cuboid or a cylinder. Although it is easy to cut and prepare, its absorption length is limited. When the laser cavity length needs to be increased, the length of the laser gain medium 20 increases accordingly, which is not conducive to the lengthwise dimension compression of the monolithic microchip laser. Therefore, the gain medium 20 of this application adopts Nd 3+ :YVO4, and in one embodiment of the present invention, the gain medium 20 further includes a bottom surface 220, the bottom surface 220 is arranged parallel to the top surface 210, and the bottom surface 220 is respectively connected to the first side surface 230 and the second side surface 240. The pump source 10 is arranged above the top surface 210 and is arranged on a side close to the first side surface 230, and then the pump light emitted by the pump source 10 can sequentially pass through the two-color film 30 arranged on the top surface 210 and then reach the first side surface 230, and then be transmitted from the first side surface 230 to the second side surface 240, and finally output through the 1064nm partial reflection film 40 arranged on the top surface 210.

[0047] In one embodiment of the present invention, the top surface 210 is set at an acute angle with the first side surface 230 and the second side surface 240, respectively, so that the cross-sectional length of the bottom surface 220 connected to the first side surface 230 and the second side surface 240 is smaller than the cross-sectional length of the top surface 210. That is, the cross-sectional shape formed by the top surface 210, the first side surface 230, the bottom surface 220, and the second side surface 240 is an inverted trapezoid. That is, the pump light emitted from the pump source 10 passes through the two-color film 30 corresponding to the first side surface 230 to reach the first side surface 230, and then transmits to the second side surface 240 and passes through the 1064nm partial reflection film 40 to output outward. That is, the laser is reflected twice in the laser resonant cavity 250, so that the direction of the laser output can be changed, and at the same time, the size of the laser resonant cavity 250 is increased, so that the power and quality of the output laser pulse can be improved, and the stability of the output laser is also improved.

[0048] It is understandable that in other embodiments, the bottom surface 220 may be removed, that is, the gain medium 20 further includes at least one third side surface 260, for example Figure 3 , for example including two third sides 260, Figure 32 is another cross-sectional structural diagram of the gain medium 20 of the present invention, and further a first Q-switched crystal 60 or a second Q-switched crystal 70 is respectively arranged on the third side surface 260. The cross-sectional shape of the gain medium 20 may be an angular pyramid, so that the laser may be reflected multiple times in the gain medium 20. It is understandable that the shape of the gain medium 20 may not be limited to an inverted trapezoid or a pentagonal pyramid, and the number of the third side surfaces 260 is not limited. As the number of the third side surfaces 260 increases, the number of the first Q-switched crystal 60 or the second Q-switched crystal 70 may also increase accordingly.

[0049] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other components or units inherent to these processes, methods, products or devices.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monolithic microchip laser, characterized in that: include: A pump source, used for emitting pump light with a wavelength of 808 nm; A gain medium, the gain medium comprising at least a top surface, a first side surface and a second side surface respectively connected to the top surface, the first side surface and the second side surface respectively being arranged at an acute angle to the top surface; A two-color film and a 1064nm partial reflection film, wherein the two-color film is arranged on the top surface and close to the pump source, and the 1064nm partial reflection film is arranged on the top surface and away from the pump source; A first Q-switched crystal and a second Q-switched crystal are respectively arranged on the first side and the second side, and the first Q-switched crystal and the second Q-switched crystal are used to generate Q-switched pulses; wherein, A laser resonant cavity is formed between the two-color film, the 1064nm partial reflection film, the first Q-switched crystal and the second Q-switched crystal, the 808nm pump light emitted by the pump source is reflected at least twice in the laser resonant cavity, and a laser with a wavelength of 1064nm is formed under the action of the gain medium, and then the laser with a wavelength of 1064nm oscillates in the laser resonant cavity, and the first Q-switched crystal and the second Q-switched crystal produce a Q-switched effect to form a pulsed laser with a wavelength of 1064nm, and then the pulsed laser with a wavelength of 1064nm is output in the form of pulses at the 1064nm partial reflection film; The first Q-switched crystal and the second Q-switched crystal are both made of two-dimensional nanomaterials, and the two-dimensional nanomaterials are graphene or molybdenum disulfide; The first Q-switched crystal and the second Q-switched crystal are respectively detachably connected to the gain medium; The first Q-switched crystal and the second Q-switched crystal are prepared on the surface of the gain medium by chemical transfer, and the first Q-switched crystal and the second Q-switched crystal are disassembled by chemical transfer; A pump collimating and focusing lens group is provided downstream of the pump source, and the pump collimating and focusing lens group is used to receive the pump light emitted by the pump source, collimate and focus the pump light, and then inject the pump light into the gain medium through the dichroic film; The included angle between the first Q-switched crystal and the top surface is the same as the included angle between the second Q-switched crystal and the top surface, so that the direction of the light received by the first Q-switched crystal is parallel to the direction of the light emitted by the second Q-switched crystal.

2. The monolithic microchip laser according to claim 1, characterized in that: The gain medium is Nd 3+ :YVO4 crystal or Nd 3+ :GdVO4 crystal.

3. The monolithic microchip laser according to claim 1, characterized in that: The two-color film fully reflects light waves with a wavelength of 1064nm and fully transmits light waves with a wavelength of 808nm; The 1064nm partial reflection film partially reflects light waves with a wavelength of 1064nm, and fully reflects light waves with a wavelength of 808nm.

4. The monolithic microchip laser according to claim 1, characterized in that: The gain medium further includes a bottom surface, which is arranged parallel to the top surface and connected to the first side surface and the second side surface respectively.

5. The monolithic microchip laser according to claim 1, characterized in that: The gain medium further includes at least one third side surface, wherein an angle between the third side surface and the top surface is smaller than an angle between the first side surface or the second side surface and the top surface, and the third side surface is connected to the first side surface and the second side surface respectively, and the pump light emitted by the pump source is reflected on the first side surface, the second side surface and the third side surface in sequence.

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