WO2013013382A1 - 基于匀化棒的多次泵浦碟片固体激光器 - Google Patents

基于匀化棒的多次泵浦碟片固体激光器 Download PDF

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Publication number
WO2013013382A1
WO2013013382A1 PCT/CN2011/077575 CN2011077575W WO2013013382A1 WO 2013013382 A1 WO2013013382 A1 WO 2013013382A1 CN 2011077575 W CN2011077575 W CN 2011077575W WO 2013013382 A1 WO2013013382 A1 WO 2013013382A1
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Prior art keywords
laser
disc
pump light
crystal
parabolic
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PCT/CN2011/077575
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English (en)
French (fr)
Inventor
朱晓
朱广志
王海林
朱长虹
郭飞
齐丽君
尚建力
熊岩
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华中科技大学
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Priority to PCT/CN2011/077575 priority Critical patent/WO2013013382A1/zh
Publication of WO2013013382A1 publication Critical patent/WO2013013382A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094084—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0602—Crystal lasers or glass lasers
    • H01S3/0604—Crystal lasers or glass lasers in the form of a plate or disc
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
    • H01S3/09415—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/042—Arrangements for thermal management for solid state lasers

Definitions

  • the invention belongs to the laser technology, and in particular relates to a disk solid laser.
  • solid-state lasers With advances in laser technology, device levels, and manufacturing capabilities, solid-state lasers have become a unique branch of the laser family with their own unique advantages and are rapidly evolving toward high average power, high beam quality, and high conversion efficiency. At present, the development of high-grade industrial solid-state lasers is very rapid, and a new generation of solid-state lasers represented by fiber lasers and disk solid-state lasers has become an important development direction. On the other hand, solid-state laser technology interpenetrates with other high-tech technologies, making solid-state lasers more and more widely used in automotive body outer panel welding, automotive panel welding and sheet metal cutting.
  • the new disc solid-state laser mainly uses a flaky laser crystal as the gain medium of the laser, and adopts end-face or side-pumping. Since the thickness of the laser crystal is very thin (the value of ⁇ /d is large, where ⁇ is the diameter of the crystal, the thickness of the d crystal), even under the conditions of liquid jet impingement cooling or high-efficiency TEC chip cooling technology, even high-power density pumping is used. When the light is pumped, the radial temperature gradient inside the crystal is small, the temperature rise is not large, and the heat flow direction in the crystal is parallel to the optical axis direction. This uniformly distributed temperature field greatly eliminates the thermal deformation of the crystal and the effect on the laser, so that the output laser has better beam quality.
  • the thickness of the disc solid-state laser gain medium is small, generally between 0.1 and 1 mm, and the effective absorption length is small, the uniformity of the multiple pumping technique and the pump spot is designed to achieve high beam quality of the disc solid-state laser.
  • One of the core technologies for high conversion efficiency operation In 2003, Steffen Eriiard et al. proposed a space rotation consisting of a single paraboloid and a polygon. Pump structure; In 2005, Steffen Erhard et al. improved the above scheme by proposing a beam-space rotation multiple pumping technique based on a single paraboloid and two large folding mirrors.
  • the above-mentioned multiple-pumping technology of the disc laser only solves the problem of multiple pumping during the pumping process, and the pumping light needs to be homogenized before entering the concentrating system, if no corresponding homogenization measures are taken, the disc
  • the temperature field distribution and gain distribution non-uniformity of the laser crystal will result in low output laser beam quality and conversion efficiency.
  • the angle between the corrective mirror and the disc directly determines the number of pump spots. The requirements for assembly and adjustment are strict.
  • An object of the present invention is to provide a disk solid-state laser that overcomes the problems and disadvantages of the prior art described above, and that achieves homogenization of a pump spot while achieving efficient pumping, and shaping the incident pump beam.
  • the homogenization requirement is low, and the system structure is simple, manufacturing and assembly are easy, and high-power, high-efficiency, high beam quality laser output can be realized.
  • the technical solution of the present invention is:
  • Multi-pumped solid-state laser based on a homogenizing rod including a semiconductor laser stack, a pump beam collimator, two identical parabolic mirrors, a cooling finger, a homogenizing rod, a resonant cavity output mirror, and a laser disc a two-parabolic mirror coaxially conjugated, wherein a laser disc crystal having an angle with the optical axis is placed at the center of the first parabolic mirror, and the laser disc crystal is placed on the cooling On the finger, a homogenizing rod is placed at the center of the second parabolic mirror; the pump light emitted by the semiconductor laser stack is collimated by the pump beam collimator, and enters the concentrating cavity between the two parabolic mirrors, after two The parabolic mirror, the disc-shaped laser crystal, and the homogenization rod are multi-reflected and concentrated on the disc-shaped laser crystal, and the disc-shaped laser crystal absorbs the pump light to generate the laser light through the cavity output mirror output.
  • the first or second parabolic mirror has a pump
  • the cooling means mainly performs high-efficiency surface cooling on the disc crystals encapsulated thereon, and can be liquid cooling using jet impingement cooling or cooling by patch or microchannel.
  • the homogenized rod is a polygonal or circular solid rod-shaped optical device (quartz) or a hollow polygonal tubular device, and its shape may be a straight line or a curved line. If the solid rod-shaped optics is used for homogenization, the material of the homogenizing rod needs to absorb the pump light very little (the fused silica material is better), and the end surface placed at the focal point of the paraboloid needs to be plated to be highly transparent to the pump light.
  • the film layer, the other end surface should be plated with a high-reflection layer for pump light, and the side surface is a polished surface.
  • the outer layer may be air or other optical material having a refractive index less than that of the rod material to ensure the transmission of total internal reflection in the homogenizing rod. If a hollow polygonal tubular device is used, a mirror that is totally reflective to the pump light is added to the end face away from the paraboloid, and the inner surface of the side surface is polished and plated with a reflection of the pump light.
  • the present invention has the following advantages -
  • Multiple pumping concentrating cavities consisting of double parabolic mirrors, disc-shaped laser crystals, and homogenizing rods do not require complex shaping, collimation, and homogenization of the light emitted by the semiconductor laser stack. Efficiently achieve multiple pumping, reasonable pump spot area and uniform power density distribution.
  • Multi-channel pump light injection to increase the maximum pump power, obtain laser output parallel to the central axis, facilitate the use of the output beam, construct a V-type or other form of laser cavity to obtain large mode volume or fundamental mode output, for multiple
  • the gain of the disc-shaped laser crystal is connected in series to obtain higher output power.
  • FIG. 1 is an overall structural view of a single beam pump optical disc laser, the pump light entrance is opened on the first parabolic side, FIG. 1 (a) is a structural view of the xz plane, and FIG. 1 (b) is a yz plane.
  • Figure 2 is a schematic diagram showing the positional relationship of the components in the concentrating cavity
  • Figure 2 is the positional relationship diagram of the components in the xz plane
  • Figure 2 (b) is the positional relationship diagram of the components in the yz plane
  • Figure 3 (a) is a solid rod-shaped optic with a polygonal or circular shape
  • Figure 3 (b) is a solid rod-shaped optic with a straight line or a curved line
  • Figure 3 (c) is a hollow rod-shaped optic with a polygonal or circular shape
  • Figure 3 (d) a hollow rod-shaped optic that is a straight line or a curved line
  • Figure 4 shows the overall structure of a single-beam pumping disc laser with the pump light entrance open on the side of the second paraboloid
  • Figure 4 (a) is a structural view of the xz plane
  • Figure 4 (b) is a structural view of the yz plane
  • Figure 5 is a structural view of the xz plane of the dual-beam pumping
  • the present invention employs one or several semiconductor laser stacks as pump sources, and a double parabolic mirror, a disc-shaped laser crystal, and a homogenizing rod constitute a multi-pump homogenizing concentrating cavity.
  • the multi-pumping of the conjugate image points is achieved by the collimation and focusing characteristics of the conjugate-mounted double parabolic mirror.
  • the disc laser crystal and the laser cavity output mirror constitute a laser cavity, and the cooling finger cools the disc-shaped laser crystal, and the two parabolic reflections have the same surface shape function.
  • the mirror is coaxially conjugated, wherein the apex of one of the parabolic mirrors is located at the focus of the other parabolic mirror; the characteristics are: the laser crystal of the disc is soldered, bonded or clamped to the end face of the cooling finger, and the disc crystal is placed at the The focal position of the two parabolic mirrors and the tilt angle 01 from the optical axis is 1 ⁇ 10°), which facilitates the formation of a resonant cavity with the output mirror.
  • the homogenizing rod is placed at the focus position of the first paraboloid and the inclination angle ⁇ with the optical axis is 0 to 10 degrees, and the strip pump light entrance is designed on the first parabolic mirror.
  • the pump light entrance has a number of offsets from the center of the first parabolic mirror along the fast axis of the semiconductor laser, and the collimated pump light enters the concentrating cavity from the rectangular entrance. After the second parabolic reflection, it is directly pumped into the disc-shaped laser crystal. Since the disc crystal has a certain angle with the optical axis, the unabsorbed light returns to the inside of the concentrating cavity and is reflected into the homogenizer. After the incident spot is homogenized, it returns to the parabolic concentrating cavity.
  • the disc and the end face of the homogenizer are respectively placed on the focal point of the conjugate paraboloid, the two are in a mutual image relationship, and the light is transmitted between the two, and finally the multi-pass pumping of the homogenized spot is completed, and the disc is formed on the disc.
  • a uniform pump spot effectively increases the light-to-light conversion efficiency of the laser.
  • the strip pump light inlet is designed on the second parabolic mirror.
  • the pump light inlet has a certain offset from the center of the second parabolic mirror along the fast axis of the semiconductor laser.
  • the pump light After the collimation, the pump light enters the concentrating cavity from the rectangular entrance, and directly enters the homogenizing rod after the first parabolic reflection. Homogenization, the homogenized light enters the inside of the multi-pass pumping concentrating cavity again for transmission. Since the disc and the homogenizer end face are respectively placed on the focal point of the conjugate paraboloid, the two images are mutually imaged, and finally the homogenized spot is completed.
  • the multi-pass pumping forms a uniform pump spot on the disc, which effectively improves the light-to-light conversion efficiency of the laser.
  • scheme 3 in order to effectively increase the input power density of the pump light, on the basis of the scheme 1, the pump light entrance of the first paraboloid is increased, and the two entrances are mirror images of each other. After the collimation, the two pumping lights with the same beam parameters enter the concentrating cavity from these rectangular inlets, and then the light transmission process is the same as that of the scheme 1, and the multi-pass pumping mode of the first pumping-stage homogenization conjugate imaging is realized. . Finally, the multi-pass pumping of the homogenized spot is completed, and a uniform pump spot is formed on the disc, thereby effectively improving the light-light conversion efficiency of the laser.
  • the entrance of the second paraboloid is increased, because the scheme is first uniformized.
  • the rod can be used to complete the homogenization of the pump light.
  • the homogenized light transmission process is the same as that of the scheme 2, and finally the multi-pass pump of the homogenized spot is completed, and a uniform pump spot is formed on the disc, thereby effectively improving the laser. Light and light conversion efficiency.
  • scheme 1 proposes a disc solid-state laser including a semiconductor laser stack 1, a pump beam collimator 2, a first parabolic mirror 3, a second parabolic mirror 4, a cooling finger 5, and a dish. a structure of a laser crystal 6, a homogenizing rod 7, a laser output mirror 8, a pump light inlet 9, and the like, wherein the first parabolic mirror 3 and the second parabolic mirror 4 are coaxially conjugated; the semiconductor laser stack 1
  • the emitted pump beam is collimated by the pumping light collimator 2 and then enters the first parabolic mirror 3, the second parabolic mirror 4, the disc-shaped laser crystal 6, and the homogenizing rod 7 through the pumping light inlet 9.
  • FIG 1 (a) is a structural view of the xz plane of the structure
  • Figure 1 (b) is a structural view of the yz plane of the structure.
  • the semiconductor laser array 1 is used as a pump source for a disc solid-state laser.
  • the divergence angle and spot size of the beam in the fast axis (X direction) and the slow axis (y direction) are different, and the beam quality is poor, so collimation is required. Can only be applied.
  • the pump beam collimator 2 collimates the beam emitted by the semiconductor laser array 1, and the diverging angles of the collimated pump beams x and y are small and equal. So that after entering the paraboloid focus The spot size meets the design requirements, resulting in a long strip of light.
  • the first parabolic mirror 3, the second parabolic mirror 4, the disc laser crystal 6, and the homogenizing rod 7 constitute a multi-pump concentrating cavity, and Fig. 2 shows the positional relationship of the components in the concentrating cavity.
  • Figure 2 is a positional relationship diagram of each component in the xz plane; 2 (b) is a positional relationship diagram of each component in the yz plane.
  • the first paraboloid 10 and the second paraboloid 11 are reflection surfaces of the first parabolic mirror 3 and the second parabolic mirror 4, respectively.
  • the first paraboloid 10 and the second paraboloid 11 have the same parabolic function, the focal length is P/2, and the vertices are separated by P/2 and coaxial.
  • the focus of the first paraboloid 10 coincides with the apex of the second paraboloid 11; the focus of the second paraboloid 11 coincides with the apex of the first paraboloid 10, so that two parabolic mirrors are conjugated.
  • the cooling finger 5 is a cooling member and a supporting portion of the disc laser crystal, and the cooling can be performed by the jet impact technique or the TEC microchannel technology to efficiently cool the soldered, pasted or clamped disc laser crystal 6 body.
  • the disc laser crystal 6 has a thickness of 0.1 mm to 1 mm and a diameter of 4 mm to 25 mm, and serves as an activation medium for the laser.
  • the side of the crystal away from the second paraboloid 11 is plated with a film layer which is highly reflective to the pump light and the output laser.
  • the film layer and the cavity output mirror 8 form a laser cavity, and the other surface is plated with pump light and output laser light. Highly permeable layer to reduce the reflection loss of pump light and output laser.
  • the disc laser crystal is soldered to the cooling finger 5 and placed in the focus area of the second parabolic mirror, which can be properly defocused during installation.
  • the angle y between the yz plane and the optical axis facilitates the formation of a resonant cavity with the output mirror 8.
  • the solid rod-shaped optics (quartz) of the homogenizing rod 7 which is polygonal or circular may also be a tubular hollow polygonal device, which may have a straight line or a curved shape.
  • One end face is placed on the paraboloid
  • the focus of the mirror 1 can be properly defocused, and the end face is plated with a high anti-reflection coating of pump light to reduce end face loss and the same size as the designed pump spot size.
  • FIG. 3 (a) shows a schematic of several homogenizing rods. Among them, 71, 72, 73, 74 are linear round bars, quadrilateral bars, hexagonal bars, and octagonal bars. 75, 76 are curved octagonal and quadrilateral homogenizing rods.
  • 71A, 72A, 73A, 74A are linear round tubes, quadrilateral round tubes, hexagonal round tubes, and octagonal round tubes, respectively.
  • One end face is equipped with mirrors of 71A-a, 72A-a, 73A-a, 74A-a; 75A, 76A are curved octagonal and quadrilateral homogenized tubes.
  • the laser output mirror 8 is an output coupling mirror, and may be a plane mirror or a curved mirror.
  • the laser full-reflection film with the end face of the disc-shaped laser crystal 6 forms a resonant cavity, realizes resonance amplification, and completes laser output.
  • the specific scheme for achieving multiple homogenization pumps is described in detail below. As shown in FIG. 1, after the collimated pump light enters from the pump light inlet 9, it is first directed to the second parabolic mirror 4, which can converge the collimated beam parallel to the axis of rotation according to the parabolic mirror.
  • the pump light is concentrated on the disc-shaped laser crystal 6; the laser crystal absorbs a part of the pump light, and the unabsorbed portion is reflected by the high reflection film of the disc-shaped laser crystal 6 and is incident on the second parabolic mirror 4 Because the normal of the reflective surface of the laser crystal is the parabolic rotation axis, so the incident and the exit The beam is at the same angle as the axis of rotation; the second parabolic mirror 4 collimates the divergent beam that is emitted from its focus into a beam parallel to the axis of rotation and is directed toward the first parabolic mirror 3; the first parabolic mirror 3 The beam is converged and transmitted to the focal point and coupled into the homogenizing rod placed at the focus.
  • the light continues to be transmitted and reflected in the inner surface of the rod, the light is continuously reflected and transformed from the end surface into the parabolic concentrating cavity. At this point, the beam is thoroughly homogenized.
  • the homogenized beam is continuously transmitted in the concentrating cavity formed by the two conjugate paraboloids.
  • the focal point of the first paraboloid 3 and the focal point of the second paraboloid 4 are mutually object-image relationship, after homogenization
  • the spot is imaged onto the disc laser crystal 6 and absorbed again by the disc laser crystal 6.
  • the unabsorbed pump light is again imaged into the homogenization rod, and the above-described transmission imaging process is repeated to achieve multiple absorption of the pump light.
  • the pump light distribution obtained on the disc laser crystal 6 is a superposition of the first pump spot and the shape of the homogenizing rod.
  • the homogenizing rod 7 can be appropriately defocused.
  • the inclination angle of the disc laser crystal 6 and the optical axis is for facilitating formation of a laser cavity with the output mirror 8, and the homogenization rod 7 and the optical axis may be perpendicular or may have a certain inclination. Only the position of the spot and the degree of homogenization at the time of imaging are changed. As shown in Fig.
  • the design of the scheme 2 can be adopted, and the overall layout is similar to the scheme 1 in which the parabolic mirror 3 and the paraboloid 4 are conjugated, and the semiconductor laser array 1 is emitted.
  • the pump beam is collimated by the pumping light collimator 2 and then enters from the pump light inlet 9 into the first parabolic mirror 3, the second parabolic mirror 4, the disc-shaped laser crystal 6, and the homogenizing rod 7.
  • the secondary pump homogenizes the concentrating cavity to realize multiple, efficient and uniform pumping; the disc laser crystal 6 and the laser cavity output mirror 8 form a resonant cavity to obtain an output laser. Specific solutions for achieving multiple pumping are described in detail below. As shown in FIG.
  • the collimated pump light first enters the first parabolic mirror 3 after entering from the pump light inlet 9, and the collimated beam can be concentrated and reflected according to the parabolic mirror.
  • the pump light is concentrated in the homogenization rod at the focus of the parabolic mirror 3 and continues to be transmitted inside the homogenization rod; since the light is constantly reflected and transformed on the inner surface of the homogenization rod, and reflected by the other end surface Will come, and finally return to the parabolic concentrating cavity from the focus of the paraboloid 3, at which point the beam is thoroughly homogenized.
  • the homogenized beam is continuously transmitted in the concentrating cavity formed by the two conjugate paraboloids.
  • the focus of the first paraboloid 3 and the focus of the second paraboloid 4 are object-image relations, so the homogenizing rod
  • the end face at the focal point of the paraboloid 3 is imaged into the interior of the disc crystal.
  • the unabsorbed pump light is further homogenized by imaging the two conjugate paraboloids into the homogenizing rod.
  • the final disc laser crystal 6 completes the high-efficiency absorption of the multi-pump light. Therefore, the pump light of the solution is multi-transmitted inside the two conjugate paraboloids while achieving homogenization, so as to improve the utilization of the pump light.
  • the pump light inlet of the first paraboloid is increased, the pump light inlet 9A and the pump are
  • the Puguang entrance 9B is mirror image of each other, and the semiconductor laser array 1A and the semiconductor laser array 1B have the same pump light collimation systems 2A and 2B, and the two pump lights having the same beam parameters are collimated from these rectangular inlets into the poly Light cavity. This ensures that the two spots pumped to the inside of the laser disc crystal have the same parameters to form a good overlap, and then the beam is transmitted in the same way as in Scheme 1, which is conjugated by a parabolic mirror and a homogenized rod.
  • the pump light inlet of the second paraboloid is increased, the pump light inlet 9A and the pump
  • the Puguang entrance 9B is mirror image of each other, and the semiconductor laser disk array 1A and the semiconductor laser disk array 1B have the same pump light collimation systems 2A and 2B, and the two paths with the same beam parameters after collimation Pump light enters the concentrating cavity from these rectangular inlets.
  • scheme 5 proposes a disc solid-state laser including a semiconductor laser stack 1, a pump beam focusing system 12, a first parabolic mirror 3, a second parabolic mirror 4, a cooling finger 5, and a disc.
  • the focusper 12 is coupled into the end face away from the parabolic focus into the homogenizing rod 7 to complete the homogenization of the pump light.
  • the homogenized pump light is multi-pumped from the end face of the homogenizing rod placed at the focus into the first parabolic mirror 3, the second parabolic mirror 4, the disc-shaped laser crystal 6, and the homogenizing rod 7.
  • the disc laser crystal 6 and the laser cavity output mirror 8 form a resonant cavity to obtain an output laser.
  • the structure of the semiconductor laser stack 1, the first parabolic mirror 3, the second parabolic mirror 4, the cooling finger 5, the disc laser crystal 6, the laser output mirror 8, and the like are the same as those described above.
  • the pump beam focusr 12 uses a series of optical elements to focus a larger spot into a smaller spot for coupling into the interior of the homogenizing rod 7.
  • the homogenizing rod 7 is a polygonal or circular solid rod-shaped optical device (quartz) which may have a straight line or a curved shape as shown in Fig. 3(b).
  • the end face of the homogenizing rod is plated with a special film layer, as shown in Fig.
  • a linear octagonal homogenizing rod, and the end surface 13 is placed at the focus of the parabolic mirror 3, and a high antireflection coating plated with pump light is parallel to the optical axis.
  • the end surface 14 is a special film layer.
  • the spot focused by the pump beam focusing system 12 enters the region of the homogenizing rod A is coated with an anti-reflection film of pump light, and the other position is plated with a highly reflective film of pump light. It is ensured that the light that is reflected back into the homogenizing rod by the double paraboloid multiple times only the light of the area A is lost, and the other areas reflect the pump back into the multiple pumping concentrating cavity.
  • the pump light emitted by the semiconductor laser array 1 is obtained by the pump beam focusing system 12 to obtain a coupling spot having a small spot size, and is homogenized by coupling the A region of the homogenizing rod end face 14 into the homogenizing rod.
  • a pump spot having a uniform intensity distribution is formed there, and since the parabolic mirror 3 and the parabolic mirror 4 are conjugated, the disc laser crystal 6 is placed on the parabolic mirror 4 At the focus of the focus, the spots at the focus are imaged with each other, and a uniform spot is imaged into the inside of the laser disc.
  • the unabsorbed light is returned to the homogenizing rod again and transferred to the end face 14 of the homogenizing rod. Part of the light is lost from the area A, and the others are reflected back, and are transmitted in a multi-pump system composed of the homogenizing rod 7, the parabolic mirror 3, the parabolic mirror 4, and the laser disc crystal 6.
  • the above process is repeated as described to form a uniform multiple pump. Ultimately achieve efficient laser output.
  • the present invention is not limited to the above specific embodiments, and those skilled in the art can implement the present invention in various other specific embodiments according to the disclosure of the present invention. Therefore, any simple design is adopted by using the design structure and ideas of the present invention. Changes or modifications are intended to fall within the scope of the invention.

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Abstract

一种碟片固体激光器，包括同轴共轭放置的两个抛物面反射镜（3，4），其中第一抛物面反射镜（3）中心处放置有与第一抛物面反射镜（3）的光轴持有夹角的激光碟片晶体（6），激光碟片晶体（6）贴放于冷却指（5）上，第二抛物面反射镜（4）的中心处放置有匀化棒（7）；半导体激光器叠阵（1）发出的泵浦光经泵浦光束准直器（2）准直后进入两抛物面反射镜（3，4）之间的聚光腔，经两抛物面反射镜（3，4）、激光碟片晶体（6）、匀化棒（7）的多次反射会聚于激光碟片晶体（6）上，激光碟片晶体（6）吸收泵浦光产生的激光经谐振腔输出镜（8）输出。本发明的碟片固体激光器在实现高效泵浦的同时实现了泵浦光斑的均匀化，同时对入射泵浦光束的整形和匀化要求较低，且系统结构简单，制造装配容易，可实现高功率，高效率、高光束质量的激光输出。

Description

基于匀化棒的多次泵浦碟片固体激光器
技术领域
本发明属于激光器技术， 具体涉及一种碟片固体激光器。
背景技术
随着激光技术、 器件水平和制造能力的不断提高， 固体激光器以其自 身独特的优点成为激光器家族中独特的一个分支， 并向着高平均功率、 高 光束质量、 高转换效率的方向快速发展。 目前高档工业固体激光器的发展 十分迅速， 以光纤激光器和碟片固体激光器为代表的新一代固体激光器成 为重要发展方向。 另一方面， 固体激光技术与其他高新技术相互渗透， 使 得固体激光器在汽车车身外板焊接、 汽车板拼焊和金属板材切割等领域有 着越来越广泛的应用。
新型碟片固体激光器主要利用薄片状激光晶体作为激光器的增益介质， 采用端面或侧面泵浦的方式。 由于激光晶体厚度很薄（Φ/d值很大， 其中 Φ 为晶体的直径， d晶体厚度）， 在液体射流冲击冷却或高效 TEC贴片冷却技 术的条件下， 即使采用高功率密度的泵浦光进行 泵浦， 晶体内部径向温度 梯度很小、 温升不大且晶体中热流方向与光轴方向平行。 这种均匀分布的 温度场极大消除了晶体的热形变和对激光的影响， 使输出的激光具有较好 的光束质量。
由于碟片固体激光器增益介质的厚度很小，一般在 0.1~lmm之间，有 效吸收长度很小， 因此多次泵浦技术和泵浦光斑的均匀性设计是实现碟片 固体激光器高光束质量、 高转换效率运行的核心技术之一。 2003年， 斯蒂 芬爱华德（Steffen Eriiard)等提出了单抛物面和多棱镜构成的空间旋转多次 泵浦的结构； 2005年， Steffen Erhard等对上述方案进行改进提出了基于单 抛物面和两个大型折叠镜实现光束空间旋转多次泵浦技术的方案。
2008年， 朱晓教授等人提出一种基于共轭双抛物面， 倾斜激光晶体、 矫正反射镜的多程泵浦结构实现泵浦光斑的多程传输， 其泵浦次数与激光 晶体和矫正镜的夹角有关。 2010年， 朱晓教授等对上述方案进行改进， 提 出集多程泵浦和高效冷却为一体的新型泵浦技术， 以及在此技术的多碟串 接技术。 进一步提高共轭双抛物面多程泵浦系统的泵浦效率和利用空间。
上述碟片激光器的多次泵浦技术在泵浦的过程中仅解决的多次泵浦 的问题， 泵浦光进入聚光系统前需要先进行匀化， 若不采取相应的匀化措 施， 碟片激光晶体的温度场分布、 增益分布的不均匀性将导致输出激光光 束质量和转换效率较低； 另一方面该方案对矫正镜和碟片之间的角度关系 直接决定泵浦光斑的次数， 在装配和调整方面要求比较严格。
发明内容
本发明的目的在于为了克服上述现有技术存在的问题及缺点， 提供一 种碟片固体激光器， 该激光器在实现高效泵浦的同时实现泵浦光斑的匀化， 对入射泵浦光束的整形和匀化要求较低， 且系统结构简单、 制造、 装配容 易， 可实现高功率、 高效率、 高光束质量的激光输出。 本发明的技术方案为：
基于匀化棒的多次泵浦碟片固体激光器， 包括半导体激光器叠阵、 泵浦 光束准直器、 两个相同的抛物面反射镜、 冷却指、 匀化棒、 谐振腔输出镜 和激光碟片晶体； 两抛物面反射镜同轴共轭放置， 其中第一抛物面反射镜 中心处安放有与光轴持有夹角的激光碟片晶体， 激光碟片晶体贴放于冷却 指上， 第二抛物面反射镜中心处安放有匀化棒； 半导体激光器叠阵发出的 泵浦光经泵浦光束准直器准直后， 进入两抛物面反射镜之间的聚光腔， 经 过两抛物面反射镜、 碟片状激光晶体、 匀化棒多次反射会聚于碟片状激光 晶体上， 碟片状激光晶体吸收泵浦光产生激光经谐振腔输出镜输出。 所述的第一或第二抛物面反射镜上开有泵浦光入口， 或者以匀化棒为 泵浦光入口。
所述的冷却指主要对封装在其上的碟片晶体进行高效的面冷却， 可以 采用射流冲击冷却的液体冷却方式也可以采用贴片或微通道的冷却方式。 所述的匀化棒为多边形或圆形的实心棒状光学器件（石英） 也可以是 空心多边形管状器件， 其外形可以是直线或曲线。 若采用实心棒状光学器 件进行匀化， 该匀化棒的材料需对泵浦光的吸收很小 （熔石英材料较好）， 其放置在抛物面焦点处的端面需镀对泵浦光高透的膜层， 另一端面需镀对 泵浦光的高反膜层， 侧面为抛光面。 其外层可以是空气或折射率小于棒体 材料的其他光学材料， 保证光线在匀化棒中实现全内反射的传输。 若采用 空心多边形管状器件， 远离抛物面的端面需增加一片对泵浦光全反射的镜 片， 侧面的内表面抛光且镀有对泵浦光反射的膜层。 具体而言， 本发明具有以下优点-
( 1 ) 双抛物面反射镜、 碟片状激光晶体、 匀化棒组成的多次泵浦聚光 腔， 不需要对半导体激光器叠阵发出的光线进行复杂的整形、 准直和匀化。 高效的实现多次泵浦， 泵浦光斑面积合理， 功率密度分布均匀。
(2 ) 本发明根据具体使用需求， 可以灵活的采用不同实施方案， 实现 多路泵浦光注入提高最大泵浦功率、 获得与中轴平行的激光输出方便对输 出光束的使用、 构建 V型或其他形式激光谐振腔以获得大模体积或基模输 出、 对多个具有增益的碟片状激光晶体串接以获得更高的输出功率。
(3 )设备体积较小、机械结构和调整简单、质量较轻， 便于工业应用。 附图说明 图 1 为单束泵浦光碟片激光器整体结构图， 泵浦光入口开在第一抛物 面一侧， 图 1 (a) 为 x-z平面的结构视图， 图 1 (b) 为 y-z平面的结构视 图； 图 2为聚光腔内各部件的位置关系示意图， 图 2 为 x-z平面的元件位 置关系图， 图 2 (b) 为 y-z平面的元件位置关系图； 图 3为匀化棒形状图， 图 3 (a)为多边形或圆形的实心棒状光学器件， 图 3 (b) 为直线或曲线的实心棒状光学器件， 图 3 (c) 为多边形或圆形的 空心棒状光学器， 图 3 (d) 为直线或曲线的空心棒状光学器件； 图 4为单束泵浦光碟片激光器整体结构图， 泵浦光入口开在第二抛物 面一侧， 图 4 (a) 为 x-z平面的结构视图， 图 4 (b) 为 y-z平面的结构视 图； 图 5为双束泵浦光碟片激光器 x-z平面的结构视图，两泵浦光入口开在 第一抛物面两侧； 图 6为双束泵浦光碟片激光器 x-z平面的结构视图，两泵浦光入口开在 第二抛物面两侧； 图 7为泵浦光从匀化棒进入聚光腔 y-z平面的结构视图； 图 8为八边形匀化棒实心或空心端面截图。 具体实施方式 本发明采用一个或若干个半导体激光器叠阵作为泵浦源， 双抛物面反 射镜、 碟片状激光晶体、 匀化棒组成多次泵浦匀化聚光腔。 利用共轭放置 的双抛物面反射镜的准直、 聚焦特性， 实现共轭像点的多次泵浦。 在第一种具体实现方式 (简称为方案 1)中， 碟片激光晶体和激光谐振 腔输出镜构成激光谐振腔， 冷却指对碟片状激光晶体进行冷却， 面形函数 相同的二个抛物面反射镜同轴共轭放置， 其中一个抛物面反射镜的顶点位 于另一个抛物面反射镜的焦点处； 其特征在于： 碟片激光晶体焊接、 粘接 或钳接于冷却指端面， 碟片晶体放置在第二抛物面反射镜的焦点位置且与 光轴之间的倾角 01为 1~10° )， 便于和输出镜构成谐振腔。匀化棒放置在第 一抛物面的焦点位置且与光轴之间的倾角 β为 0~10度，条形泵浦光入口设 计在第一抛物面反射镜上。 泵浦光入口较第一抛物面反射镜的中心沿半导 体激光器快轴方向存在若干偏移， 准直后泵浦光从该矩形入口进入聚光腔。 经过第二抛物面反射后直接泵浦到碟片状激光晶体内部， 由于碟片晶体与 光轴存在一定的夹角， 未被吸收的光线再次回到聚光腔内部经反射进入匀 化器完成对入射光斑的匀化后回到抛物面聚光腔。 由于碟片与匀化器端面 分别放置在共轭抛物面的焦点上， 两者相互物像关系， 光线在两者之间相 互传输， 最终完成匀化光斑的多程泵浦， 在碟片上形成均匀的泵浦光斑， 有效提高激光器的光光转换效率。 在第二种具体实现方式 (简称为方案 2)中， 与方案 1 的区别是， 条形 泵浦光入口设计在第二抛物面反射镜上。 泵浦光入口较第二抛物面反射镜 的中心沿半导体激光器快轴方向存在若干偏移， 准直后泵浦光从该矩形入 口进入聚光腔， 经过第一抛物面反射后直接进入匀化棒中进行匀化， 匀化 后的光线再次进入多程泵浦聚光腔内部进行传输， 由于碟片与匀化器端面 分别放置在共轭抛物面的焦点上， 两者相互成像， 最终完成匀化光斑的多 程泵浦， 在碟片上形成均匀的泵浦光斑， 有效提高激光器的光光转换效率。 在第三种具体实现方式 (简称为方案 3) 中， 为有效提高泵浦光的输入 功率密度， 在方案 1 的基础上， 对第一抛物面的泵浦光入口进行增加， 两 入口互为镜像， 准直后光束参数相同的两路泵浦光从这些矩形入口进入聚 光腔， 此后光线的传输过程与方案 1 相同， 实现第一次泵浦后期匀化共轭 成像的多程泵浦方式。 最终完成匀化光斑的多程泵浦， 在碟片上形成均匀 的泵浦光斑， 有效提高激光器的光光转换效率。 在第四种具体实现方式 (简称为方案 4) 中， 为有效提高泵浦光的输入 功率密度， 在方案 2 的基础上， 对第二抛物面的入口进行增加， 由于该方 案是采用先匀化在共轭成像的多程泵浦方式， 因此对增加入口的位置和入 射泵浦光的参数没有严格的限制， 只要保证如何光进入多程泵浦系统受经 第一次聚焦能有效进入匀化棒即可， 从而完成泵浦光的匀化， 匀化后的光 线传输过程与方案 2相同， 最终完成匀化光斑的多程泵浦， 在碟片上形成 均匀的泵浦光斑， 有效提高激光器的光光转换效率。 第五种具体实现方式 （简称为方案 5) 中， 为减少多次泵浦腔内的光 线从入口处漏光， 将半导体激光器阵列通过半导体激光器聚焦系统直接耦 合进匀化棒内进行匀化， 然后通过放置在抛物面焦点上的端面注入到双抛 物面聚光腔内， 根据共轭抛物面的互成像原理， 匀化后的光斑就直接成像 到碟片激光晶体内部， 部分被吸收后。 剩余的光束再次回到运化棒内进行 匀化， 如此往复形成多次泵浦。 下面结合附图和实例对本发明作进一步详细的说明。 如图 1所示， 方案 1提出一种碟片固体激光器， 包括半导体激光器叠 阵 1、 泵浦光束准直器 2、 第一抛物面反射镜 3、 第二抛物面反射镜 4、 冷 却指 5、 碟片激光晶体 6、 匀化棒 7、 激光输出镜 8、 泵浦光入口 9等结构， 其中， 第一抛物面反射镜 3和第二抛物面反射镜 4为同轴共轭放置； 半导 体激光器叠阵 1发射的泵浦光束经过泵浦光准直器 2准直后经泵浦光入口 9 进入由第一抛物面反射镜 3、 第二抛物面反射镜 4、 碟片状激光晶体 6、 匀 化棒 7构成的多次泵浦匀化聚光腔内， 实现多次、 高效、 均匀的泵浦； 碟 片激光晶体 6与激光谐振腔输出镜 8构成谐振腔获得输出激光。 其中图 1 (a) 为该结构的 x-z平面的结构视图， 图 1 (b) 为该结构 y-z平面的结构 视图。 半导体激光器叠阵 1作为碟片固体激光器的泵浦源， 此光束在快轴 （X 方向）和慢轴 （y方向） 的发散角以及光斑尺寸均不同， 光束质量较差， 因 此需进行准直后才能应用。 泵浦光束准直器 2将半导体激光器叠阵 1所发出的光束进行准直， 经 准直后的泵浦光束 x、 y方向发散角较小且相等。 使得进入抛物面聚焦后的 光斑尺寸达到设计的要求， 从而获得一长条形的光斑。 从抛物面镜 3 上的 入口进入多次泵浦聚光腔内。 第一抛物面反射镜 3、 第二抛物面反射镜 4、 碟片激光晶体 6、 匀化棒 7构成多次泵浦聚光腔， 图 2 给出了聚光腔内各部件的位置关系。 其中图 2 为 x-z平面的各元件的位置关系图； 2 (b) 为 y-z平面各元件的位置关 系图。 第一抛物面 10、 第二抛物面 11分别为第一抛物面反射镜 3、 第二抛 物面反射镜 4的反射面。第一抛物面 10、第二抛物面 11具有相同的抛物线 函数， 焦距均为 P/2， 顶点相距 P/2且同轴。 第一抛物面 10的焦点与第二 抛物面 11的顶点重合;第二抛物面 11的焦点与第一抛物面 10的顶点重合， 所以说两个抛物面反射镜共轭放置。 冷却指 5为碟片激光晶体的冷却部件和支撑部分， 其冷却可采用射流 冲击技术或 TEC微通道技术对焊接、 粘贴或夹持的碟片激光晶 6体进行高 效冷却。 碟片激光晶体 6厚度为 0.1mm~lmm， 直径为 4mm~25mm， 作为激光 器的激活介质。 该晶体远离第二抛物面 11的一面镀有对泵浦光和输出激光 高反的膜层， 该膜层与谐振腔输出镜 8构成激光谐振腔， 另一面镀有对泵 浦光和输出激光的高透膜层， 以减少泵浦光和输出激光的反射损耗。 碟片 激光晶体焊接在冷却指 5 上并放在第二抛物面镜的焦点区域， 安装中可以 适当离焦。 在 yz平面与光轴夹角 α便于和输出镜 8构成谐振腔。 匀化棒 7 的为多边形或圆形的实心棒状光学器件 （石英） 也可以是管 状空心多边形器件， 其外形可以是直线或曲线。 其一个端面放置在抛物面 镜 1 的焦点上可以适当离焦， 该端面镀有泵浦光的高增透膜以减少端面损 耗，尺寸与所设计的泵浦光斑尺寸相同。在 yz平面内与光轴夹角 β为 0~10 度范围以内 （该角度过大会造成碟片上多次泵浦光斑畸变较为严重）。 匀化 棒 7 的另一端面镀有泵浦光的高反射膜， 将进入棒内的光线反射回多次泵 浦聚光腔内。 图 3 (a) (b)给出了几种匀化棒的示意图。 其中 71， 72， 73， 74分别为直线型圆棒、 四边形棒、 六边形棒、 八边形棒。 75， 76为弯曲的 八边形和四边形匀化棒。 若采用管状空心多边匀化器， 则管子内壁需镀对 泵浦光高反的膜层， 在远离抛物面焦点的端面需装配对泵浦光高反的镜片。 如图 3 (c) (d) 所示， 其中 71A， 72A， 73A， 74A分别为直线型圆管、 四 边形圆管、六边形圆管、八边形圆管。一个端面装配有 71A-a， 72A-a， 73A-a， 74A-a的反射镜； 75A， 76A为弯曲型的八边形和四边形匀化管。 一个端面 装配有 75A-a， 76A-a的反射镜。 激光输出镜 8为输出耦合镜， 可以为平面镜、 也可以为曲面镜。 其与 碟片状激光晶体 6—端面的激光全反膜构成谐振腔， 实现谐振放大， 完成 激光输出。 实现多次匀化泵浦的具体方案在下文有详细介绍。 如图 1所示， 经过准直的泵浦光从泵浦光入口 9进入后首先射向第二 抛物面反射镜 4，根据抛物面反射镜能将平行于旋转轴的准直光束反射会聚 于焦点的原理， 泵浦光被会聚于碟片状激光晶体 6上； 激光晶体吸收一部 分泵浦光， 未被吸收的部分被碟片状激光晶体 6 的高反膜反射并射向第二 抛物面反射镜 4， 因为激光晶体反射面法线即抛物面旋转轴， 故入射、 出射 光束与旋转轴夹角相同； 第二抛物面反射镜 4将从其焦点射出的发散光束 反射准直为平行于旋转轴的光束并射向第一抛物面反射镜 3 ;第一抛物面反 射镜 3 又将光束会聚传输到焦点处， 并耦合到放置在焦点处的匀化棒内， 由于光线在匀化棒内继续传输在棒内表面不断的反射和变换， 最终从该端 面出射到抛物面聚光腔内， 此时光束被彻底匀化。 被匀化的光束就在两共 轭抛物面所构成的聚光腔内不断的传输， 根据成像理论， 第一抛物面 3 的 焦点和第二抛物面 4 的焦点处互为物像关系， 经匀化后的光斑成像到碟片 激光晶体 6上， 被碟片激光晶体 6再次吸收。 未被吸收的泵浦光再次成像 到匀化棒内， 重复上述传输成像过程， 实现泵浦光的多次吸收。 此时碟片 激光晶体 6上获得的泵浦光分布为第一次泵浦光斑和匀化棒形状的叠加。 在安装碟片状激光晶体 6、匀化棒 7可以适当的离焦。碟片激光晶体 6与光 轴的倾角是为了方便与输出镜 8构成激光谐振腔， 匀化棒 7与光轴的可以 垂直也可以存在一定的倾角。 仅改变成像时的光斑位置和匀化程度。 如图 4所示， 为进一步提高激光碟片晶体泵浦光斑的均匀性， 可采用 方案 2的设计， 整体布局与方案 1 类似抛物面镜 3和抛物面 4共轭放置， 半导体激光器叠阵 1发射的泵浦光束经过泵浦光准直器 2准直后从泵浦光 入口 9进入由第一抛物面反射镜 3、 第二抛物面反射镜 4、 碟片状激光晶体 6、匀化棒 7构成的多次泵浦匀化聚光腔内， 实现多次、高效、均匀的泵浦; 碟片激光晶体 6与激光谐振腔输出镜 8构成谐振腔获得输出激光。 具体实 现多次泵浦的具体方案在下文有详细介绍。 如图 4所示， 经过准直的泵浦光从泵浦光入口 9进入后首先射向第一 抛物面反射镜 3，根据抛物面反射镜能将平行于旋转轴的准直光束反射会聚 于焦点的原理， 泵浦光被会聚于抛物面镜 3 焦点处的匀化棒内并在匀化棒 内继续传输； 由于光线在匀化棒内表面不断的反射和变换， 并由另一端面 反射会来， 最终从抛物面 3 的焦点处回到抛物面聚光腔内， 此时光束被彻 底匀化。 被匀化的光束就在两共轭抛物面所构成的聚光腔内不断的传输， 根据成像理论， 第一抛物面 3 的焦点和第二抛物面 4的焦点处互为物像关 系， 因此匀化棒在抛物面 3焦点处的端面被成像到碟片晶体内部， 碟片吸 收部分泵浦光后， 未被吸收的泵浦光通过两共轭抛物面在成像到匀化棒内 进一步匀化， 上述过程如此往复， 最终碟片激光晶体 6完成多泵浦光的高 效吸收， 因此该方案泵浦光在实现匀化的同时再两共轭抛物面内部多次传 输， 以提高泵浦光的利用率。 如图 5所示， 为进一步提高泵浦光的功率密度， 实现更高功率的激光 输出， 在方案 1 的基础上， 对第一抛物面的泵浦光入口进行增加， 泵浦光 入口 9A和泵浦光入口 9B互为镜像， 半导体激光碟阵 1A和半导体激光器 碟阵 1B具有相同泵浦光准直系统 2A和 2B，经准直后光束参数相同的两路 泵浦光从这些矩形入口进入聚光腔。 这样可以保证第一次泵浦到激光碟片 晶体内部的两个光斑具有相同的参数形成较好的重叠， 此后光束的传输方 式与方案 1 相同， 经共轭抛物面镜、 匀化棒的多次传输与成像， 实现激光 晶体的匀化和多次泵浦， 提高激光器的泵浦效率。 如图 6所示， 为进一步提高泵浦光的功率密度， 实现更高功率的激光 输出， 在方案 2 的基础上， 对第二抛物面的泵浦光入口进行增加， 泵浦光 入口 9A和泵浦光入口 9B互为镜像， 半导体激光碟阵 1A和半导体激光器 碟阵 1B具有相同泵浦光准直系统 2A和 2B，经准直后光束参数相同的两路 泵浦光从这些矩形入口进入聚光腔。 这样可以保证第一次泵浦到激光碟片 晶体内部的两个光斑具有相同的参数形成较好的重叠， 此后光束的传输方 式与方案 1 相同， 经共轭抛物面镜、 匀化棒的多次传输与成像， 实现激光 晶体的匀化和多次泵浦， 提高激光器的泵浦效率。 如图 7所示， 方案 5提出了一种碟片固体激光器包括半导体激光器叠 阵 1、 泵浦光束聚焦系统 12、 第一抛物面反射镜 3、 第二抛物面反射镜 4、 冷却指 5、 碟片激光晶体 6、 匀化棒 7、 激光输出镜 8等结构， 其中， 第一 抛物面反射镜 3和第二抛物面反射镜 4为共轭放置； 半导体激光器叠阵 1 发射的泵浦光束经过泵浦光聚焦器 12耦合到远离抛物面焦点的端面进入匀 化棒 7 内， 完成对泵浦光进行匀化。 经匀化后的泵浦光从放置在焦点处匀 化棒端面进入第一抛物面反射镜 3、 第二抛物面反射镜 4、 碟片状激光晶体 6、匀化棒 7构成的多次泵浦匀化聚光腔内， 实现多次、高效、均匀的泵浦; 碟片激光晶体 6与激光谐振腔输出镜 8构成谐振腔获得输出激光。 其中半 导体激光叠阵 1， 第一抛物面镜 3， 第二抛物面反射镜 4、 冷却指 5、 碟片 激光晶体 6、 激光输出镜 8等结构与上述方案相同。 泵浦光束聚焦器 12， 采用一系列光学元件将尺寸较大的光斑聚焦为较 小的光斑便于耦合到匀化棒 7内部。 匀化棒 7为多边形或圆形的实心棒状光学器件（石英）， 其外形可以是 直线或曲线， 如图 3 (b)所示。 匀化棒端面镀有特殊膜层， 如图 8所示一 直线形八边形匀化棒， 端面 13放置在抛物面镜 3的焦点处， 镀有泵浦光的 高增透膜， 与光轴平行放置也可存在一定的倾角； 端面 14为一特殊膜层， 经过泵浦光束聚焦系统 12聚焦的光斑进入匀化棒的区域 A镀有泵浦光的增 透膜， 其他位置镀有泵浦光的高反射膜。 保证经双抛物面多次反射回到匀 化棒内的光线仅区域 A的光线损耗掉， 其他区域将泵浦反射回多次泵浦聚 光腔内。 具体实现多次泵浦的具体方案在下文有详细介绍。 如图 7所示， 半导体激光器叠阵 1所发出的泵浦光经泵浦光束聚焦系 统 12获得光斑尺寸较小的耦合光斑， 通过匀化棒端面 14的 A区耦合进匀 化棒进行匀化， 传输到放在在抛物面镜 3焦点处的端面 13后， 在该处形成 强度分布均匀的泵浦光斑， 由于抛物面镜 3和抛物面镜 4共轭放置， 碟片 激光晶体 6放置在抛物面镜 4的焦点处， 所以焦点处的光斑相互成像， 均 匀的光斑被成像到激光碟片内部， 未被吸收的光线则再一次回到匀化棒内， 传输到匀化棒端面 14处， 此时仅部分光线从区域 A损耗掉， 其他则被反射 回去， 在匀化棒 7、 抛物面镜 3， 抛物面镜 4， 激光碟片晶体 6所构成的多 次泵浦系统中传输。 上述过程如此反复从而形成均匀的多次泵浦。 最终实 现高效的激光输出。 本发明不仅局限于上述具体实施方式， 本领域一般技术人员根据本发明公 开的内容， 可以采用其它多种具体实施方式实施本发明， 因此， 凡是采用 本发明的设计结构和思路， 做一些简单的变化或更改的设计， 都落入本发 明保护的范围。

Claims

权 利 要 求
1、 基于匀化棒的多次泵浦碟片固体激光器， 包括半导体激光器叠阵、 泵浦光束准直器、 两个相同的抛物面反射镜、 冷却指、 匀化棒、 谐振腔输 出镜和激光碟片晶体；
两抛物面反射镜同轴共轭放置， 其中第一抛物面反射镜中心处安放有 与光轴持有夹角的激光碟片晶体， 激光碟片晶体贴放于冷却指上， 第二抛 物面反射镜中心处安放有匀化棒； 半导体激光器叠阵发出的泵浦光经泵浦 光束准直器准直后， 进入两抛物面反射镜之间的聚光腔， 经过两抛物面反 射镜、 碟片状激光晶体、 匀化棒多次反射会聚于碟片状激光晶体上， 碟片 状激光晶体吸收泵浦光产生激光经谐振腔输出镜输出。
2、 根据权利要求 1所述的多次泵浦碟片固体激光器， 其特征在于， 还 在第一或第二抛物面反射镜上开有泵浦光入口， 或者以匀化棒作为泵浦光 入口。
3、 根据权利要求 1所述的碟片固体激光器， 其特征在于， 所述匀化棒 为直线型或弯曲型棱柱。
4、根据权利要求 1或 3所述的多次泵浦碟片固体激光器，其特征在于， 所述匀化棒为端面为多边形的棱柱。
5、根据权利要求 1或 3所述的多次泵浦碟片固体激光器，其特征在于， 所述匀化棒为空心棱柱， 匀化棒的反射端设有反射镜。
6、根据权利要求 1或 3所述的多次泵浦碟片固体激光器，其特征在于， 所述匀化棒为实心棱柱， 匀化棒的透射端面镀有增透膜， 反射端面镀有高 反膜。 、 根据权利要求 1或 3所述的多次泵浦碟片固体激光器， 其特征在于， 所
PCT/CN2011/077575 2011-07-25 2011-07-25 基于匀化棒的多次泵浦碟片固体激光器 WO2013013382A1 (zh)

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