JP4925059B2 - Solid state laser module - Google Patents

Description

  The present invention relates to a solid-state laser module.

  FIG. 13 to FIG. 17 show a configuration example of a conventional solid-state laser module, and the problems are also shown.

  FIG. 13 is a diagram showing a configuration (part 1) of a conventional solid-state laser module.

  In FIG. 13, 101 is a semiconductor laser light source, 102 is an excitation optical system, and 103 is a laser resonator. Reference numeral 104 denotes a module support portion on which each optical component is fixed and supported, 105 denotes a module fixing / cooling surface which fixes the module and is cooled from the outside, 106 denotes excitation light, 107 denotes an optical axis of the laser resonator 103, 108 Indicates the output laser light from the laser resonator 103, and 109 indicates the flow of heat. Here, the laser resonator 103 has resonator mirrors at both ends, between which a solid laser medium, an optical switch element that controls laser generation, a polarization control element, and a nonlinear optical that converts the wavelength of the laser light. Elements and the like are arranged according to applications. As the cooling structure of this solid-state laser module, as shown by the heat flow 109 in FIG. 13, the heat generated from each component during the operation of the module through the module support portion 104 that fixes and supports the entire components constituting the module, In particular, the heat generated from the solid laser medium in the semiconductor laser light source 101 for excitation and the laser resonator 103 is propagated in the direction perpendicular to the optical axis 107 and is exhausted from the module fixing / cooling surface 105. . The heat propagated to the module fixing / cooling surface 105 is completely exhausted to the outside of the module by a Peltier element or a cooling medium such as water brought into close contact with the module fixing / cooling surface 105 (see Patent Document 1 below).

  In addition, an example in which a semiconductor laser light source for excitation and an excitation optical system are installed outside the module, and only the laser resonator is configured on the module support portion to exhaust heat is shown (see Patent Document 2 below).

  FIG. 14 is a diagram showing a configuration (part 2) of a conventional solid-state laser module.

  In this figure, 110 is a module holding unit, 111 is a semiconductor laser light source, 112 is an excitation optical system, 113 is a laser resonator, 114 is a module support, 115 is a module fixing / cooling surface, 116 is excitation light, and 117 is light. The axis, 118 indicates the output laser beam, and 119 indicates the heat flow.

  As described above, the module holding part 110 that serves both as holding and releasing heat is provided so as to surround each element constituting the solid-state laser module, and these are similarly arranged on the common module support part 114. An example is also shown (see Patent Document 3 below). In the configuration example of the solid-state laser module as shown in FIG. 14, even if the heat generated from the element temporarily propagates through the module holding unit 110 around the element, the heat is finally generated with respect to the optical axis 117. The heat flow 119 in the vertical direction propagates to the direction module support 114 and is exhausted out of the module (see Patent Document 3 below).

  FIG. 15 is a diagram showing a configuration (part 3) of a conventional solid-state laser module.

  In this figure, 201 is a laser diode, 202 is a condensing optical system, 203 is a total reflection mirror, 204 is a solid laser medium, 205 is an output mirror, 206 is a module holding unit, 207 is a heat radiation fin, 208 is an optical axis, 209 Indicates the flow of heat.

  In such a conventional solid-state laser module structure, each element constituting the module is held by a surrounding module holding unit 206, and is provided in close contact with the laser diode 201 that generates the largest amount of heat, and a heat radiation fin 207 is provided.

In this configuration, heat generated from each element is transmitted to the surrounding module holding unit 206, propagates in the direction of the heat flow 209 parallel to the optical axis 208, and is exhausted from the radiation fins 207 to the outside of the module (the following patents). Reference 4).
JP 2000-349371 A JP 2003-115628 A JP 2007-81233 A JP-A-9-116216

  However, in the structure of the conventional example shown in FIG. 13, a temperature gradient is formed in the module support portion 104 in the direction perpendicular to the optical axis 107. Therefore, as shown in FIG. Due to the thermal expansion of the material, the module is deformed into a convex shape. For this reason, there is a possibility that the excitation light 106 and the optical axis 107 deviate from the optimum conditions at the time of design, and the output of the output laser light obtained with the passage of time may decrease, or the direction and shape of the laser beam may be deformed. . For example, in a module support portion 104 made of copper having excellent heat conduction and having a length of 5 cm and a thickness of 0.5 cm, if a temperature difference of 20 ° C. is generated at the top and bottom, it is predicted that a warp of 0.1 mm will occur at the maximum. The

  Further, the same applies to the conventional example shown in FIG. 14 described above. Finally, in order to exhaust heat in the direction perpendicular to the optical axis 117 through the module holding part 110 and the module support part 114, as shown in FIG. There is a possibility that a temperature difference occurs between the upper and lower surfaces of the module holding unit 110 and the module support unit 114, warping occurs, and the optical axis 117 is shifted.

  Further, in the conventional example of FIGS. 13 and 14, when the module is controlled and the Peltier element as an electronic cooling element is brought into close contact with the module fixing / cooling surfaces 105 and 115 for fixing and cooling the module, The warp generated during operation of the Peltier element itself propagates directly as stress to the module, and the optical axis of the module may be further shifted.

  Further, in the conventional example shown in FIG. 15, since the heat exhaust direction is parallel to the optical axis 208, the optical axis 208 is unlikely to be shifted as in other conventional examples, but the direction of exhaust heat is the most calorific value. Therefore, there is a possibility that the exhaust heat from the laser diode 201 raises the temperature of the radiating fin 207 and the heat from the laser resonator, particularly the solid laser medium 204, is not efficiently exhausted.

  Further, when the heat dissipation performance of the heat dissipating fins 207 is lower than the heat generated by the laser diode 201, the heat generated from the laser diode 201 may flow backward to the laser resonator side, resulting in unstable operation.

  In view of the above situation, an object of the present invention is to provide a solid-state laser module that can maintain a stable laser output for a long time.

  Furthermore, an object of the present invention is to provide a solid-state laser module that can maintain a stable laser output for a long time, and in which the optical components constituting them can be easily replaced.

In order to achieve the above object, the present invention provides
[1] A semiconductor laser light source for exciting a solid laser medium, an excitation optical system for shaping the excitation light emitted from the semiconductor laser light source and guiding it to the solid laser medium, at least the solid laser medium and the solid laser medium In the solid-state laser module having a laser resonator including a resonator mirror that resonates laser light emitted from the semiconductor device, the excitation optical system and the laser resonator are linearly arranged to form an optical axis, and the semiconductor Heat generated in the laser light source and the laser resonator propagates in the surrounding module holding portion in a direction along the optical axis, and is outside the periphery of the semiconductor laser light source and the laser resonator, and the semiconductor laser light source Fix the module through the module support provided in the middle area of the laser resonator Through the cooling surface, characterized in that it has to be waste heat to outside the module.

  [2] In the solid-state laser module according to [1], the module holding unit is fixed to a plate-like holding block in which the semiconductor laser light source, the excitation optical system, the laser resonator, and its components are independent from each other. Each plate-like holding block is penetrated by at least one rod-shaped guide in the optical axis direction, and is fixed to the module support portion in a desired order.

  [3] The solid-state laser module according to [1] or [2], wherein the module support portion is disposed so as to protrude from a lower portion where the excitation optical system is disposed.

  [4] In the solid-state laser module according to [1], the fixing / cooling surface of the module is connected to the module support portion, and a Peltier element is connected to the fixing / cooling surface. The area is smaller than the area of the Peltier element.

  According to the present invention, since the heat generated from the semiconductor laser light source and the laser resonator propagates along the optical axis in the surrounding module holding part, the temperature gradient of the module holding part is formed in the optical axis direction. Even if the holding part is thermally expanded, the optical axis remains straight and does not warp, so oscillation does not become unstable. Furthermore, the heat transmitted through the module support provided outside the semiconductor laser light source and the laser resonator and in the middle between them is discharged from the module fixing / cooling surface to the outside of the module to generate it in the semiconductor laser light source. Heat is not transferred to the laser resonator. In addition, the module support part has a cross-sectional area as a heat conduction path, and the area of the Peltier element is smaller than that of the Peltier element. Little is transmitted to the resonator. Thereby, the output laser beam stabilized for a long time can be maintained.

  The solid-state laser module of the present invention includes a semiconductor laser light source 1 for exciting a solid-state laser medium, an excitation optical system 2 for shaping the excitation light 9 emitted from the semiconductor laser light source 1 and guiding it to the solid-state laser medium, and at least A solid-state laser module including a laser resonator 3 including a resonator mirror that includes the solid-state laser medium and resonates laser light emitted from the solid-state laser medium, the semiconductor laser light source 1, the excitation optical system 2, and a laser The resonators 3 are arranged in a straight line to form an optical axis 7, and heat generated in the laser resonator 3 including the semiconductor laser light source 1 and a solid laser medium therein is generated in the surrounding module holding unit 4. Is propagated in a direction along the optical axis 7 and around the semiconductor laser light source 1 and the laser resonator 3. An outer, and is the waste heat to the outside of the module through the module fixing and cooling surfaces 6 transmitted the module support part 5 which is provided in an intermediate region therebetween.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a schematic diagram showing the basic configuration of the solid-state laser module of the present invention, and FIG. 2 is a conceptual diagram showing the effect of the solid-state laser module.

  As shown in these drawings, the solid-state laser module shapes the semiconductor laser light source 1 for exciting a solid-state laser medium (not shown) and the excitation light 9 emitted from the semiconductor laser light source 1 and guides it to the solid-state laser medium. An excitation optical system 2 and a laser resonator 3 that includes a solid-state laser medium and resonates laser light emitted from the solid-state laser medium are provided. The semiconductor laser light source 1, the excitation optical system 2, the solid laser medium, and the laser resonator 3 are linearly arranged to form an optical axis 7, and the laser resonance including the semiconductor laser light source 1 and the solid laser medium therein. The heat generated in the vessel 3 propagates in the direction along the optical axis 7 in the surrounding module holder 4. The heat flow A is transferred to the outside of the module through the module fixing / cooling surface 6 through the module support 5 provided in a region other than the periphery of the semiconductor laser light source 1 and the laser resonator 3 and between them. Can be heated.

  Since it comprised in this way, the area of the module support part 5 is smaller than the area of the Peltier device 10 closely_contact | adhered to the module fixing / cooling surface 6. Therefore, even if the temperature control by the Peltier element 10 is performed, the warp of the Peltier element 10 is hardly transmitted to the laser resonator 3 as shown in the conceptual diagram of FIG. Thereby, the output laser beam 8 stable for a long time can be maintained.

  Hereinafter, specific examples of the solid-state laser module of the present invention will be described.

  3 is a top view showing a cross-sectional state in which the solid-state laser module according to the first embodiment of the present invention is disassembled, FIG. 4 is a top view showing a cross-sectional state in which the solid-state laser module is assembled, and FIG. FIG. 6 is a side view showing a sectional state in which the solid-state laser module is assembled, and FIG. 7 is a side view of the solid-state laser module as seen from the laser emission side.

  In these drawings, 11 is a semiconductor laser element (light source), 12 is a condenser lens (excitation optical system), 13 is a laser resonator, and this laser resonator 13 includes a solid-state laser medium 14, an optical switch element 15, It consists of an output mirror 16. 17 is an optical axis, 18 is excitation light, 19 is output laser light, 20 is a guide, 21, 23, 24, and 25 are holding blocks, 22 is a module support portion, 26 is a module support portion 22 and holding blocks 21 and 23, and It is a contact surface with which adjacent holding blocks 23 to 25 abut. Reference numeral 29 denotes a module fixing / cooling surface, and 30 denotes a Peltier element.

  More specifically, in FIG. 3, 11 is a semiconductor laser element (light source) for exciting a solid laser medium having a wavelength of 808 nm, 12 is a pump laser beam emitted from the semiconductor laser element 1, and is collected in a solid laser medium. A condensing lens (excitation optical system) 13 for emitting light is a laser resonator. The laser resonator 13 includes a solid-state laser medium 14, an optical switch element 15, and an output mirror 16. The solid laser medium 14 has Nd of 1 at. % YAG (yttrium, aluminum, garnet) containing 3% in diameter and 4 mm in length (rod). On the surface of the YAG rod on the side of the excitation optical system, a coating film having a high reflection of 99% or more with respect to laser oscillation light having a wavelength of 1064 nm and a transmittance of 95% or more with respect to excitation light having a wavelength of 808 nm is formed. The laser resonance occurs between this film and the output mirror 16 having a reflectance of 50% with respect to the oscillation light, and the film is taken out through the output mirror 16. The optical switch element 15 is YAG containing Cr and has a transmittance of 60% for light of 1064 nm. The diameter is 3 mm as in the solid laser medium 14. As shown in FIG. 3, each element is fixed to individual plate-like holding blocks 21, 23, 24, 25 except for the condenser lens 12. These holding blocks 21, 23, 24, and 25 are made of copper having high thermal conductivity, and the surfaces of the opposing blocks are processed into smooth planes so that heat conduction is performed well when they are brought into contact with each other. Furthermore, each holding block 21, 23, 24, 25 and the module support portion 22 are formed with two through holes 21a, 22a, 23a, 24a, 25a, respectively, and two cylindrical columns made of stainless steel having a diameter of 3 mm. The guide 20 is penetrated. The optical axis position of each element is fixed by this guide 20, and even if the holding blocks 21, 23, 24, 25 move along the guide 20, the optical axis 17 does not come off. Furthermore, the opposing surfaces of the blocks 21, 23, 24, and 25 are processed with high accuracy so as to be perpendicular to the guide 20, and no gap is generated even if they are brought into close contact with each other.

  FIG. 4 is a top view of the holding blocks 21, 23, 24, and 25 in close contact with the guide 20 in the direction of the module support portion 22.

  FIG. 5 shows a cross section of the solid-state laser module from the side. Through holes 21 a, 22 a, 23 a, 24 a, through which the guides 20 are passed through the holding blocks 21, 23, 24, 25 and the module support 22. Apart from 25a, holes 21b, 23b, 24b, 25b of fixing screws 28a, 28b for fixing each holding block 21, 23, 24, 25 in close contact with the module support portion 22 side are formed. The fitting portions 27 of the fixing screws 28 a and 28 b are formed on the inner surface of the hole 22 b formed in the module support portion 22.

  FIG. 6 is a side view showing a cross section in which the holding blocks 21, 23, 24, and 25 are overlapped and closely adhered to the module support portion 22 along the guide 20 by rotating these fixing screws 28 a and 28 b. FIG. The holding blocks 21, 23, 24, and 25 are brought into close contact with each other so that heat generated from each element is propagated in the direction of the heat flow A shown in FIG. 6 and transmitted to the module support portion 22 through the contact surface 26. Then, heat is exhausted from the module fixing / cooling surface 29.

  FIG. 7 is a side view of the solid-state laser module as viewed from the output mirror side, and shows the positional relationship between the guide 20, the fixing screw 28 b, and the output mirror 16.

  FIG. 8 is a side view showing a sectional state in which the solid state laser module according to the second embodiment of the present invention is assembled.

  In this embodiment, the structure of the side surface of the solid laser module different from that of the first embodiment is shown, and the fitting portions 27a and 27b of the fixing screws 28c and 28d are connected to the holding blocks 21 and 25 at both ends of the solid laser module. Each is provided. By providing the fitting portions 27a and 27b of the fixing screws 28c and 28d independently on the pumping semiconductor laser element (light source) side and the laser resonator side, the fixing screws for the thickness and combination of the respective holding blocks. The degree of freedom of the lengths 28c and 28d is improved.

  FIG. 9 is a top view showing a sectional state in which a solid state laser module according to a third embodiment of the present invention is disassembled, and FIG. 10 is a top view showing a sectional state in which the solid state laser module is assembled.

  In these drawings, the pumping semiconductor laser element (light source) 11 and the condenser lens (pumping optical system) 12 are integrated in a fixed position in a holding block 31 in advance, as shown in FIG. The structure is inserted into the module support portion 32. A screw may be formed and inserted into the holding block 31 and the fitting portion 34 of the module support portion 32, or may be fixed to the module support portion 32 with a through screw from the outside. The structure of the laser resonator 13 is the same as in FIG. Reference numeral 33 denotes a guide.

  With such a structure, even when the condenser lens 12 is replaced, it is not necessary to remove or replace the module support portion 32, so that the maintainability of the solid laser module is greatly improved.

  FIG. 11 is a top view showing a sectional state in which a solid state laser module according to a fourth embodiment of the present invention is disassembled, and FIG. 12 is a side view showing a sectional state in which the solid state laser module is assembled.

  As shown in these drawings, in this embodiment, an excitation light source 35 is disposed in the holding block 31, and the excitation light is propagated through the optical fiber 36 as the excitation light source 35.

  FIG. 12 shows a structure viewed from the side in a state in which the holding block 31 is fitted to the module support portion 32 and assembled in the disassembled configuration shown in FIG. 11, and in this embodiment, the module support is shown. The part 32 is disposed so as to protrude below the position where the condenser lens 12 is disposed. Since the excitation optical system comprising the condenser lens 12 generates little heat and is in the middle of the excitation light source 35 and the laser resonator 13, a module support 32 connected to the module fixing / cooling surface 29 is provided at that site. By providing, it is possible to configure a solid-state laser module that suppresses thermal interference between the two and that operates stably and is less affected by distortion of the optical axis 17 due to heat. Reference numeral 28e denotes a fixing screw.

It should be noted that the present invention is not limited to the above-described embodiment, and based on the gist of the present invention shown in FIG. Various modifications are possible and are not excluded from the scope of the invention. For example, YAlO ₃ , YVO ₄ , Y ₂ O ₃ , YLF, KGW, KYW, GdVO ₄ , LiSAF, LiCAF, GGG, GSGG, etc. may be used as the base material of the solid laser medium. Further, the laser element to be added may be Yb, Ho, Tm, Er, Pr, or a combination thereof other than Nd. It is selected appropriately according to the required laser wavelength and output. Further, a semiconductor laser element (light source) that performs excitation is selected to have an appropriate wavelength and output in accordance with the absorption characteristics of the solid laser medium to be used. Further, when there are a plurality of absorption wavelengths even in the same laser medium, the optimum wavelength is selected according to the purpose. The condensing lens as the excitation optical system is appropriately selected from the core diameter of the semiconductor laser element for excitation or the optical fiber and the necessary condensing beam diameter. One condenser lens may be arranged, or a plurality of condenser lenses may be arranged in series.

In the embodiment of the present invention, Cr: YAG is used as an optical switch element in the laser resonator, but Co: Spinel, V: YAG, or SAM which is a semiconductor material may be used. Further, KTP, LBO, BBO, LiNbO ₃ (LN), KNbO ₃ (KN), LiTaO ₃ (LT), GdYCOB, or the like may be inserted as the nonlinear optical element. An active Q switch element, a polarization control element, a lens, or the like may be inserted. Of course, only a solid laser medium may be used. A suitable optical element can be fixed to the holding block in accordance with a required function, and can be inserted into the module in the required number and order. As a laser resonance method, a combination of one-side coating of a solid laser medium and an output mirror may be used as in the embodiment, or two individual mirrors may be used. Furthermore, it is also possible to directly coat one end face of the optical element to be inserted so as to have the same effect as the output mirror.

  In addition, a cylindrical guide is shown as an example, but any shape may be used as long as it functions as a guide for defining the position of the optical axis, and the cross section may be a polygon. Further, the arrangement position may be anywhere, and it may be formed in a rail shape and provided below the holding block. The number may be one, three or more. Furthermore, since the position of the optical axis need only be defined without using a guide that penetrates each holding block, for example, a projection or the like that is positioned on the opposite surface of each holding block is provided and fitted to each other. And may be integrated.

  In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.

  The solid-state laser module of the present invention can supply a stable laser output for a long time in various industrial / physical application fields using laser light.

It is a schematic diagram which shows the basic composition of the solid-state laser module of this invention. It is a conceptual diagram which shows the effect by the solid state laser module of this invention. It is a top view which shows the cross-sectional state by which the solid-state laser module which shows 1st Example of this invention was decomposed | disassembled. It is a top view which shows the cross-sectional state by which the solid-state laser module which shows 1st Example of this invention was assembled. It is a side view which shows the cross-sectional state by which the solid-state laser module which shows 1st Example of this invention was decomposed | disassembled. It is a side view which shows the cross-sectional state by which the solid-state laser module which shows 1st Example of this invention was assembled. It is the side view which looked at the solid-state laser module which shows 1st Example of this invention from the laser emission side. It is a side view which shows the cross-sectional state by which the solid state laser module which shows 2nd Example of this invention was assembled. It is a top view which shows the cross-sectional state by which the solid-state laser module which shows 3rd Example of this invention is decomposed | disassembled. It is a top view which shows the cross-sectional state by which the solid-state laser module which shows 3rd Example of this invention was assembled. It is a top view which shows the cross-sectional state by which the solid-state laser module which shows 4th Example of this invention is decomposed | disassembled. It is a side view which shows the cross-sectional state by which the solid state laser module which shows 4th Example of this invention was assembled. It is a figure which shows the structure (the 1) of the conventional solid state laser module. It is a figure which shows the structure (the 2) of the conventional solid state laser module. It is a figure which shows the structure (the 3) of the conventional solid state laser module. It is a figure which shows the deformation | transformation by the heat | fever of the conventional solid-state laser module (the 1) shown by FIG. It is a figure which shows the deformation | transformation by the heat | fever of the conventional solid-state laser module (the 2) shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser light source 2 Excitation optical system 3,13 Laser resonator 4 Module holding part 5,22,32 Module support part 6,29 Module fixed and cooling surface 7,17 Optical axis 8,19 Output laser light 9,19 Excitation light A Heat flow 10,30 Peltier element 11 Semiconductor laser element (light source)
12 Condensing lens (excitation optical system)
14 Solid laser medium 15 Optical switch element 16 Output mirror 20, 33 Guide 21, 23, 24, 25, 31 Holding block 21a, 22a, 23a, 24a, 25a Guide through hole 21b, 22b, 23b, 24b, 25b For fixing Screw hole 26 Contact surface 27, 27a, 27b Fixing screw fitting portion 28a, 28b, 28c, 28d, 28e Fixing screw 34 Module support fitting portion 35 Excitation light source 36 Optical fiber

Claims (4)

  A semiconductor laser light source for exciting the solid laser medium, an excitation optical system for shaping the pump light emitted from the semiconductor laser light source and guiding it to the solid laser medium, and at least the solid laser medium and the solid laser medium In a solid-state laser module including a laser resonator including a resonator mirror that resonates laser light, the excitation optical system and the laser resonator are linearly arranged to form an optical axis, and the semiconductor laser light source and Heat generated in the laser resonator propagates in the surrounding module holder in the direction along the optical axis, and is outside the semiconductor laser light source and the laser resonator, and the semiconductor laser light source and the laser resonator The module fixing / cooling surface is transferred through the module support provided in the middle area Solid-state laser module, characterized in that it has to be waste heat to the module externally.   2. The solid-state laser module according to claim 1, wherein the module holding unit is formed by fixing the semiconductor laser light source, the excitation optical system, the laser resonator, and the component parts thereof to independent plate-like holding blocks. Each of the plate-like holding blocks is penetrated by at least one rod-shaped guide in the axial direction, and is stacked and fixed in a desired order on the module support portion.   3. The solid-state laser module according to claim 1, wherein the module support portion is disposed so as to protrude from a lower portion where the excitation optical system is disposed.   2. The solid laser module according to claim 1, wherein a fixing / cooling surface of the module is connected to the module support portion, a Peltier element is connected to the fixing / cooling surface, and a cross-sectional area of the module support portion is Solid laser module characterized in that it is smaller than the area of the Peltier element.

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