Optical device, light source device, and optical fiber laser

Abstract

To provide an optical device, light source device, and optical fiber laser that can suppress inconvenience due to increase in temperature of optical components.SOLUTION: An optical device comprises: a base 101; a plurality of light emitting elements 100a that is provided in the base, and outputs laser light; and a plurality of optical components that is provided in the base, and transmits the laser light output from the light emitting element to an optical fiber 120. The plurality of optical components includes: a first condensing lens 105 that condenses the laser light from the plurality of light emitting elements toward an end part of an optical fiber; and a second condensing lens 104 that condenses the laser light from the plurality of light emitting elements toward the first condensing lens. The first condensing lens and second condensing lens are made from synthetic silica, and intermediate members 130A1 and 130A2 of which a thermal expansion coefficient is a value between a thermal expansion coefficient of the synthetic silica and a thermal expansion coefficient of the base are provided between the first condensing lens and second condensing lens, and, the base.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical device, a light source device, and an optical fiber laser. [Background technology]

[0002] Conventionally, optical devices are known that guide laser light output from multiple light-emitting elements to an end of an optical fiber via multiple optical components (for example, Patent Document 1). In the optical device of Patent Document 1, multiple light-emitting elements and multiple optical components are mounted on a heat-dissipating base. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 134911 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of optical device, since a plurality of laser beams are guided to the end of one optical fiber, the energy density is high especially in the latter stage, i.e., in the optical components closer to the end of the optical fiber, and therefore the temperature is likely to increase due to absorption of the laser beam, etc. If such a temperature rise in the optical components causes an excessive difference in thermal expansion between the optical components and the base, it may cause an undesirable phenomenon such as the optical components being misaligned with respect to the base.

[0005] Therefore, one of the objects of the present invention is to provide an optical device, a light source device, and an optical fiber laser having a new and improved configuration that makes it possible to suppress inconveniences caused by, for example, temperature increases in optical components. [Means for solving the problem]

[0006] The optical device of the present invention comprises, for example, a base, a plurality of light-emitting elements mounted on the base and outputting laser light, and a plurality of optical components mounted on the base and transmitting the laser light output from the light-emitting elements to an optical fiber, the plurality of optical components including a first focusing lens that focuses the laser light from the plurality of light-emitting elements toward an end of the optical fiber, and a second focusing lens that focuses the laser light from the plurality of light-emitting elements toward the first focusing lens, the first focusing lens and the second focusing lens being made of synthetic quartz, and an intermediate member having a thermal expansion coefficient between the thermal expansion coefficient of the synthetic quartz and the thermal expansion coefficient of the base is provided between the first focusing lens and the second focusing lens and the base.

[0007] In the optical device, the first condensing lens and the second condensing lens may each be fixed to the intermediate member via an adhesive.

[0008] The optical device may include, as the intermediate member, a first intermediate member interposed between the first focusing lens and the base.

[0009] The optical device may include an end cap that is integrated with an end of the optical fiber and has an end face with an area larger than a cross-sectional area of ​​the optical fiber, and the first intermediate member may be a first support member provided on the base and supporting the optical fiber, the end cap, and the first focusing lens.

[0010] The optical device may include a second support member provided on the base and supporting the optical fiber, and the first intermediate member may be interposed between the second support member and the first focusing lens.

[0011] The optical device may include, as the intermediate member, a second intermediate member interposed between the second condenser lens and the base.

[0012] The optical device may include, as the intermediate member, a third intermediate member interposed between the first and second condenser lenses and the base.

[0013] The optical device may include an end cap that is integrated with an end of the optical fiber and has an end face with an area larger than the cross-sectional area of ​​the optical fiber, and the third intermediate member may be a third support member provided on the base and supporting the optical fiber, the end cap, the first focusing lens, and the second focusing lens.

[0014] In the optical device, the difference between the thermal expansion coefficient of the synthetic quartz and the thermal expansion coefficient of the intermediate member is 11×10 -6 It may be less than [1 / K].

[0015] In the optical device, the difference between the thermal expansion coefficient of the intermediate member and the thermal expansion coefficient of the base is 11×10 -6 It may be less than [1 / K].

[0016] In the optical device, the wavelength of the laser light may be not less than 400 [nm] and not more than 520 [nm].

[0017] In the optical device, the first condenser lens and the second condenser lens may have an absorptance of 0.1% or less for the laser light.

[0018] In the optical device, the optical fiber may have an optical output of 100 W or more.

[0019] In the optical device, the material constituting the intermediate member may have a lower absorptance for light with a wavelength of 400 nm or more and 520 nm or less than that of the material constituting the base.

[0020] In the optical device, the intermediate member may be made of a copper-tungsten alloy or aluminum oxide.

[0021] The optical device of the present invention, for example, comprises a base, a plurality of light-emitting elements mounted on the base and outputting laser light, and a plurality of optical components mounted on the base and transmitting the laser light output from the light-emitting elements to an optical fiber, wherein the plurality of optical components include a focusing lens that focuses the laser light from the plurality of light-emitting elements, and an intermediate member is provided between the focusing lens and the base, the intermediate member having a thermal expansion coefficient that is a value between the thermal expansion coefficient of the focusing lens and the thermal expansion coefficient of the base.

[0022] In the optical device, the condenser lens may be fixed to the intermediate member via an adhesive.

[0023] The optical device may include a cooling mechanism for cooling the intermediate member.

[0024] A light source device of the present invention includes, for example, the optical device.

[0025] Moreover, an optical fiber laser of the present invention includes, for example, the light source device and an optical amplifying fiber that amplifies the laser light output from the light source device. Effect of the Invention

[0026] According to the present invention, it is possible to obtain an optical device, a light source device, and an optical fiber laser having a more improved and novel configuration. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is an illustrative schematic plan view of the optical device according to the first embodiment. [Diagram 2] FIG. 2 is an illustrative schematic plan view of a light emitting module included in the optical device of the first embodiment. [Diagram 3] FIG. 3 is an illustrative schematic perspective view of a base included in the optical device according to the first embodiment. [Figure 4] FIG. 4 is an illustrative schematic perspective view of a support structure included in the optical device of the first embodiment. [Diagram 5] FIG. 5 is an illustrative schematic plan view of an optical fiber and an end cap included in the optical device of the first embodiment. [Figure 6] FIG. 6 is a graph showing an example of the correlation between the content of B2O3 in the material of the lens included in the optical device of the first embodiment and the temperature of the lens. [Figure 7] FIG. 7 is an illustrative schematic perspective view of a support structure included in the optical device according to the second embodiment. [Figure 8] FIG. 8 is an illustrative schematic plan view of the optical device according to the third embodiment. [Figure 9] FIG. 9 is an illustrative schematic side view of a subunit included in the optical device of the third embodiment. [Figure 10] FIG. 10 is an illustrative schematic plan view of the optical device according to the fourth embodiment. [Figure 11] FIG. 11 is an exemplary schematic configuration diagram of a light source device according to the fifth embodiment. [Figure 12] FIG. 12 is an exemplary schematic configuration diagram of the optical fiber laser according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments shown below, and the actions and results (effects) brought about by the configurations are merely examples. The present invention can be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0029] The following embodiments have similar configurations. Therefore, according to the configurations of the respective embodiments, similar actions and effects based on the similar configurations can be obtained. In the following, the similar configurations are given the same reference numerals, and duplicated descriptions may be omitted.

[0030] In this specification, ordinal numbers are given for the sake of convenience to distinguish between parts, portions, etc., and do not indicate a priority order or sequence.

[0031] In each drawing, the X1 direction is represented by an arrow X1, the X2 direction is represented by an arrow X2, the Y direction is represented by an arrow Y, and the Z direction is represented by an arrow Z. The X1 direction, the Y direction, and the Z direction intersect with each other and are perpendicular to each other. The X1 direction and the X2 direction are opposite to each other.

[0032] 1 and 8 to 10, the optical path of the laser light L is indicated by a solid arrow.

[0033] [First embodiment] FIG. 1 is a schematic configuration diagram of an optical device 100A (100) according to the first embodiment, and is a plan view of the inside of the optical device 100A as viewed in the opposite direction to the Z direction.

[0034] 1, the optical device 100A includes a base 101, a plurality of subunits 100a, a light combining unit 108, condenser lenses 104 and 105, and an optical fiber 120. The laser light output from the light emitting module 10 of each subunit 100a is transmitted to an end (not shown) of the optical fiber 120 via the mirror 103, the light combining unit 108, and the condenser lenses 104 and 105 of each subunit 100a, and is optically coupled to the optical fiber 120. The optical device 100A may also be referred to as a light emitting device.

[0035] The base 101 is made of a material with high thermal conductivity, such as a copper-based material or an aluminum-based material. The base 101 may be composed of one component or multiple components. The base 101 is covered with a cover (not shown). The multiple subunits 100a, the multiple mirrors 103, the light combining unit 108, the condenser lenses 104 and 105, and the end of the optical fiber 120 are all provided on the base 101 and are accommodated in a storage chamber (not shown) formed between the base 101 and the cover. In this embodiment, the storage chamber is hermetically sealed, but is not limited to this.

[0036] The optical fiber 120 is an output optical fiber, and is fixed to the base 101 via a support structure 110 that supports an end portion of the optical fiber 120. The optical output from the optical fiber 120 is, for example, 100 [W] or more.

[0037] The subunit 100a (100a1, 100a2) includes a light emitting module 10, a lens 43A, and a mirror 103. The lens 43A collimates the laser light of the light emitting module 10 in the Y direction, that is, in the slow axis.

[0038] Fig. 2 is a plan view showing the light emitting module 10. As shown in Fig. 2, the light emitting module 10 has a subassembly 30. Note that in Figs. 1 and 2, the optical axis of the laser light is indicated by a dashed dotted line Ax.

[0039] The subassembly 30 includes a submount 31, a light emitting element 32, and a lens 42A.

[0040] The submount 31 has, for example, a rectangular parallelepiped shape that is thin and flat in the Z direction. The submount 31 is made of an insulating material such as aluminum nitride (AIN), ceramic, or glass. Alternatively, the submount 31 may be made of silicon carbide or diamond, which have a relatively high thermal conductivity. A metallized layer 31a is formed on the submount 31 as an electrode that supplies power to the light-emitting element 32.

[0041] The light emitting element 32 is, for example, a semiconductor laser element having a fast axis (FA) and a slow axis (SA) and an output of 5 [W] or more. The light emitting element 32 extends in the X1 direction. The light emitting element 32 emits laser light in the X direction from an emission opening (not shown) provided in an emission surface 32a located at an end in the X1 direction perpendicular to the Z direction. In this embodiment, the fast axis of the light emitting element 32 is along the Z direction, and the slow axis is along the Y direction. The light emitting element 32 outputs laser light of, for example, 400 [nm] or more and 520 [nm] or less.

[0042] The lens 42A is attached to an end surface of the submount 31 in the X1 direction, and is disposed adjacent to the emission surface 32a of the light-emitting element 32 in the X1 direction. The lens 42A refracts and transmits the laser light from the light-emitting element 32. The laser light emitted from the light-emitting element 32 and transmitted through the lens 42A travels in the X direction. The lens 42A is, for example, a collimating lens, and collimates the laser light in the fast axis. The lens 42A is an example of an optical component that transmits the laser light from the light-emitting module 10 to the optical fiber 120.

[0043] Furthermore, the light emitting module 10 may have a housing 20. In the example shown in Fig. 2, the housing 20 of the light emitting module 10 is partially broken away to show the internal configuration of the light emitting module 10. In the example shown in Fig. 2, the submount 31 is mounted on the bottom wall 21 of the housing 20, and the light emitting element 32 is provided on the base 101 via the housing 20 and the submount 31. Furthermore, the lens 42A is provided on the base 101 via the housing 20 and the submount 31.

[0044] The housing 20 has a box-like shape and may also be referred to as a housing. The housing 20 forms an accommodation chamber R therein. The housing 20 accommodates the subassembly 30 in the accommodation chamber R. The housing 20 hermetically seals the accommodation chamber R, thereby preventing liquid, gas, dust, and the like from acting on the subassembly 30 from outside the housing 20. In addition, for example, an inert gas or dry air is sealed in the accommodation chamber R.

[0045] The housing 20 is made of a copper-based material, such as copper or a copper alloy.

[0046] The bottom wall 21 of the housing 20 is made of a copper-based material such as copper or a copper alloy, and is located at an end of the housing 20 opposite the Z direction. The bottom wall 21 intersects with the Z direction and extends in the X and Y directions. The bottom wall 21 has a rectangular, plate-like shape.

[0047] In addition, since the bottom wall 21 of the housing 20 is preferably made of a material with high thermal conductivity, it may be made of a material different from the other parts of the housing 20. More specifically, for example, the bottom wall 21 may be made of a copper-based material such as copper or a copper alloy with high thermal conductivity, and the side walls and the lid (not shown) of the housing 20 may be made of another material, for example, an iron-nickel-cobalt alloy.

[0048] A front wall 22, which is one of the side walls of the housing 20, is located at the end in the X1 direction of the housing 20. The front wall 22 intersects with the X1 direction and extends in the Y direction and the Z direction. The front wall 22 has a rectangular, plate-like shape.

[0049] Further, an opening 22a is provided in the front wall 22. A window member 23 is fitted in the opening 22a. The window member 23 has a property of transmitting laser light. In other words, the window member 23 is transparent to the laser light emitted by the light emitting element 32.

[0050] FIG. 3 is a perspective view of the base 101. As shown in FIG. 3, the surface 101b of the base 101 is provided with a plurality of steps 101b1 in which the positions of the subunits 100a are shifted in the opposite direction to the Z direction as they move in the Y direction. For each of the arrays A1 and A2 in which the subunits 100a are arranged at a predetermined interval (for example, a constant interval) in the Y direction, the subunits 100a are arranged on each of the steps 101b1. As a result, the Z-direction positions of the subunits 100a included in the array A1 are shifted in the opposite direction to the Z direction as they move in the Y direction, and the Z-direction positions of the subunits 100a included in the array A2 are also shifted in the opposite direction to the Z direction as they move in the Y direction. With this configuration, in each of the arrays A1 and A2, parallel laser beams aligned in the Z direction traveling in the Y direction can be input from the plurality of mirrors 103 to the light combining unit 108. The step 101b1 may be configured to be shifted in a direction inclined in the Y direction or in the opposite direction to the Y direction with respect to the Z direction, so that the laser light travels from each mirror 103 in a direction having a predetermined elevation angle with respect to the Y direction.

[0051] 1, the laser light from each mirror 103 is input to the light combining section 108 and combined in the light combining section 108. The light combining section 108 includes a combiner 108a, a mirror 108b, and a 1 / 2 wavelength plate 108c.

[0052] The mirror 103, the combiner 108a, the mirror 108b, and the half-wave plate 108c are examples of optical components that transmit the laser light from the light-emitting module 10 to the optical fiber 120. These optical components are provided directly on the base 101 or indirectly via other members.

[0053] Mirror 108b directs the laser light from subunit 100a of array A1 through half-wave plate 108c to combiner 108a, which rotates the plane of polarization of the light from array A1.

[0054] On the other hand, the laser light from subunit 100a of array A2 is input directly to combiner 108a.

[0055] The combiner 108a combines the laser lights from the two arrays A1 and A2. The combiner 108a may also be referred to as a polarization combining element.

[0056] The laser light from the combiner 108a is focused by the focusing lenses 104 and 105 toward an end (not shown) of the optical fiber 120, optically coupled to the optical fiber 120, and transmitted through the optical fiber 120. The focusing lens 104 focuses the laser light in the fast axis toward the focusing lens 105. The focusing lens 105 focuses the laser light in the slow axis toward an end (end cap, not shown) of the optical fiber 120. The focusing lenses 104 and 105 are examples of optical components that transmit the laser light from the light emitting module 10 to the optical fiber 120. The focusing lens 104 is an example of a second focusing lens, and the focusing lens 105 is an example of a first focusing lens.

[0057] The base 101 is provided with a refrigerant passage 109 for cooling the subunit 100a (light emitting module 10), the support structure 110 (support member 111A), the condenser lenses 104 and 105, the combiner 108a, the intermediate members 130A1 and 130A2, and the like. In the refrigerant passage 109, for example, a refrigerant such as a cooling liquid flows. The refrigerant passage 109 passes, for example, near the mounting surface of each component of the base 101, for example directly below or in the vicinity thereof, and the inner surface of the refrigerant passage 109 and the refrigerant (not shown) in the refrigerant passage 109 are thermally connected to the components and parts to be cooled, i.e., the subunit 100a, the support structure 110, the condenser lenses 104 and 105, the combiner 108a, the intermediate members 130A1 and 130A2, and the like. Heat exchange occurs between the refrigerant and the components and parts via the base 101, and the components are cooled. Incidentally, inlet 109a and outlet 109b of refrigerant passage 109 are provided, for example, at ends of base 101 on the opposite side in the Y direction, but may be provided at other positions. Refrigerant passage 109, together with a refrigerant pump, a valve, a control device for the pump, the valve, etc., configures a cooling mechanism.

[0058] 1 and 3, a support member 111A of the support structure 110 is provided on the surface 101b of the base 101. The support member 111A is fixed to the base 101 and supports the optical fiber 120, the condenser lens 105, and the like. In other words, the support member 111A is interposed between the base 101 and optical components such as the optical fiber 120 and the condenser lens 105. The support member 111A is an intermediate member 130A1 and is an example of a first support member and a first intermediate member.

[0059] Fig. 4 is a perspective view of the support structure 110. As shown in Fig. 4, the support structure 110 has a support member 111A, a cover 112, and a holder 114, and supports the optical fiber 120, the end cap 113, and the condenser lens 105.

[0060] The support member 111A has a rectangular parallelepiped shape extending in the Y direction, and supports the optical fiber 120 extending in the Y direction. The support member 111A also has a surface 111a facing the direction opposite to the Z direction, and a surface 111b facing the Z direction.

[0061] The cover 112 intersects and is perpendicular to the Z direction. The cover 112 has a rectangular, plate-like shape that is short in the X1 and X2 directions, long in the Y direction, and thin in the Z direction.

[0062] Both the support member 111A and the cover 112 are made of a material with high thermal conductivity.

[0063] The optical fiber 120 is partially accommodated in a housing chamber 140 that is provided between the support member 111A and the cover 112 and extends in the X direction. A light processing mechanism that processes leaked light from the optical fiber 120 may be provided in the housing chamber 140.

[0064] The cover 112 is fixed to the support member 111A by fasteners 116, such as screws. The optical fiber 120 is supported by the support member 111A and the cover 112.

[0065] The end cap 113 is surrounded by a support member 111A and a holder 114 located on the opposite side of the support member 111A. The holder 114 is attached to the support member 111A by a fastener 116 such as a screw, with the end cap 113 sandwiched between the holder 114 and the support member 111A. The end cap 113 is integrated with the peeled end portion 120a (core wire 121) of the optical fiber 120 by, for example, fusion splicing.

[0066] The condenser lens 105 is fixed onto the surface 111b of the support member 111A by a bonding material (not shown) such as an adhesive. The bonding material is, for example, an electromagnetic wave curing adhesive, a thermosetting adhesive, or a moisture curing adhesive.

[0067] Fig. 5 is a plan view showing the tip of the optical fiber 120 and the end cap 113. In Fig. 5, the optical path of the laser light L up to the tip 120a1 of the core wire 121 of the optical fiber 120 in the end cap 113 is shown by a broken line. If the laser light focused by the focusing lens 105 or the like arrives toward the tip 120a1 of the peeled end portion 120a in a configuration in which the end cap 113 is not provided, the power density becomes excessively large as the beam diameter becomes small at the tip 120a1, which is the interface, and this causes an excessive temperature rise, which may damage the tip 120a1. In this embodiment, the laser light L reaches the end face 113a1 of the end cap 113, which is wider than the tip 120a1, i.e., wider than the cross-sectional area of ​​the optical fiber 120, with a larger beam diameter and a smaller power density, so that it is possible to suppress an excessive temperature rise and damage in both the end face 113a1, which is the interface, and the tip 120a1 of the core wire 121. The end cap 113 may also be referred to as a mitigating member.

[0068] An AR (anti-reflection) coating is applied to an end face 113a1 of the end cap 113 opposite to the protruding portion 113b, thereby suppressing light reflection at the end face 113a1.

[0069] 1 and 3, an intermediate member 130A2 is provided on the surface 101b of the base 101. The intermediate member 130A2 is fixed to the base 101 and supports the condenser lens 104. In other words, the intermediate member 130A2 is interposed between the base 101 and the condenser lens 104 as an optical component. The intermediate member 130A2 is fixed to the base 101 by, for example, joining with a joining material such as solder, wax, or adhesive, or by welding. The condenser lens 104 is fixed to the intermediate member 130A2 by, for example, a joining material (not shown) such as an adhesive. The joining material is, for example, an electromagnetic wave curing adhesive, a thermosetting adhesive, or a moisture curing adhesive. The intermediate member 130A2 is an example of a second intermediate member.

[0070] The condenser lenses 104, 105 are made of, for example, synthetic quartz. Synthetic quartz has a low absorptivity for laser light. Therefore, by making the condenser lenses 104, 105 from synthetic quartz, it is possible to suppress a rise in temperature of the condenser lenses 104, 105 due to absorption of laser light. From this perspective, it is preferable that the absorptivity of the condenser lenses 104, 105 for laser light having a wavelength of 400 nm or more and 520 nm or less is 0.1% or less.

[0071] The inventors performed an experiment in which the optical device 100A was fitted with condenser lenses 105 made of materials with different contents (mass contents) of boron oxide (B2O3), and laser light was irradiated to measure the optical characteristics such as the temperature and optical output of the condenser lens 105 in each case. FIG. 6 is a graph showing the correlation between the content of boron oxide and the maximum temperature of the condenser lens 105. The horizontal axis of the graph is the mass content (mass [%]) of boron oxide (B2O3) in the condenser lens 105, and the vertical axis is the temperature [°C] of the condenser lens 105. In this experiment, the wavelength of the laser light was 465 [nm], and the total power of the laser light was 220 [W]. It can be seen from FIG. 6 that the higher the content of boron oxide, the higher the temperature of the condenser lens 105.

[0072] As a result of this experiment, the temperature threshold Tth (maximum temperature) of the condenser lens 105 at which the optical characteristics of the optical device 100A fell within the expected range was 57°C, and the mass content threshold Pth (maximum content) of boron oxide corresponding to the threshold Tth was 2%. In other words, it was found that the mass content of boron oxide in the material of the condenser lenses 104 and 105 is preferably 2% (mass%] or less.

[0073] In the above-mentioned configuration, it is preferable that intermediate member 130A1 is made of a material whose thermal expansion coefficient is a value between that of condenser lens 105 and that of base 101, and intermediate member 130A2 is made of a material whose thermal expansion coefficient is a value between that of condenser lens 104 and that of base 101. If condenser lenses 104, 105 are directly attached to base 101, the difference in volume change caused by temperature change between condenser lenses 104, 105 and base 101 becomes large due to the difference between the thermal expansion coefficient of base 101 made of, for example, a copper-based metal and the thermal expansion coefficient of condenser lenses 104, 105 made of, for example, synthetic quartz. If such a difference in volume change exceeds a range in which the bonding state of the adhesive that fixes the condenser lenses 104, 105 to the base 101 can be maintained, the condenser lenses 104, 105 may shift, tilt, or come off from the base 101, and the optical device 100A may not be able to obtain the desired optical characteristics. In this regard, in this embodiment, the condenser lenses 104, 105 are fixed to the base 101 via the intermediate members 130A1, 130A2, so that the difference in volume change caused by temperature change between the condenser lenses 104, 105 and the intermediate members 130A1, 130A2 can be made smaller, and the difference in volume change caused by temperature change between the intermediate members 130A1, 130A2 and the base 101 can be made smaller. This makes it easier to maintain the fixed state of the focusing lenses 104, 105 by the base 101 via the intermediate members 130A1, 130A2 in the desired state, thereby preventing the optical device 100A from failing to achieve the desired optical characteristics due to changes in the relative position or attitude of the focusing lenses 104, 105 with respect to the base 101.

[0074] The material of such intermediate members 130A1 and 130A2 is preferably, for example, a copper-tungsten alloy (e.g., containing Cu at a mass content of about 10 to 20%), aluminum oxide, etc. In order to suppress heat generation due to stray light (leakage light) in the optical device 100A, it is preferable that the intermediate members 130A1 and 130A2 are made of a material that has a lower absorptance of laser light having a wavelength of 400 nm or more and 520 nm or less than the material constituting the base 101 (copper in this embodiment).

[0075] Furthermore, the inventors have conducted extensive research and have found that the difference between the thermal expansion coefficient of condenser lens 104 made of synthetic quartz and the thermal expansion coefficient of intermediate member 130A2, the difference between the thermal expansion coefficient of condenser lens 105 made of synthetic quartz and the thermal expansion coefficient of intermediate member 130A1, the difference between the thermal expansion coefficient of intermediate member 130A2 and the thermal expansion coefficient of base 101, and the difference between the thermal expansion coefficient of intermediate member 130A1 and the thermal expansion coefficient of base 101 are all less than 11×10 -6 It has been confirmed that if the difference is [1 / K] or less, the desired reliability can be ensured for the fixed state of the focusing lenses 104, 105 relative to the base 101, and thus, a degradation in the optical characteristics of the optical device 100A due to deviations in the position or attitude of the focusing lenses 104, 105 does not occur or is at a level that is not problematic.

[0076] As described above, in this embodiment, the condenser lenses 104 and 105 are made of synthetic quartz. The condenser lenses 104 and 105 receive a plurality of laser beams, and the condenser lens 105 receives the beam condensed from the condenser lens 104, so that the laser beam is input with a relatively high energy density. For this reason, the condenser lenses 104 and 105, and especially the condenser lens 105, are more likely to increase in temperature than other optical components except for the end cap 113. If the condenser lenses 104 and 105 experience an excessive temperature rise, this may result in a decrease in reliability of the fixed state of the condenser lenses 104 and 105 relative to the base 101, and therefore a decrease in reliability of the optical characteristics of the optical device 100A. In this regard, in the present embodiment, since the focusing lenses 104, 105 are made of synthetic quartz, which has a low absorptance of laser light, excessive temperature rise in the focusing lenses 104, 105 can be suppressed, and thus deterioration in reliability of the fixed state of the focusing lenses 104, 105 to the base 101 and the accompanying deterioration in reliability of the optical characteristics of the optical device 100A can be suppressed.

[0077] In this embodiment, the condenser lenses 104, 105 are fixed to the base 101 via intermediate members 130A1, 130A2, and the thermal expansion coefficients of the intermediate members 130A1, 130A2 are between the thermal expansion coefficients of the condenser lenses 104, 105 and the thermal expansion coefficient of the base 101. With this configuration, it becomes easier to maintain the condenser lenses 104, 105 in the intended fixed state, compared to when the condenser lenses 104, 105 are directly fixed to the base 101.

[0078] [Second embodiment] 7 is a perspective view of the support structure 110 of the second embodiment. Except for the support structure 110 being different, the optical device 100B (100) of this embodiment has a similar configuration to the optical device 100A of the first embodiment.

[0079] In the support structure 110 of this embodiment, a plate-shaped intermediate member 130B is interposed between the support member 111B and the condenser lens 105. The intermediate member 130B is not interposed between the support member 111B and the end cap 113. In this embodiment, the intermediate member 130B is made of a material whose thermal expansion coefficient is between the thermal expansion coefficient of the condenser lens 105 and the thermal expansion coefficient of the base 101, and is specifically made of a copper-tungsten alloy or aluminum oxide. In the optical device 100B having such a configuration, the intermediate member 130B is provided between the base 101 and the condenser lens 105, thereby obtaining the same effect as in the first embodiment. The intermediate member 130B is an example of a first intermediate member, and the support member 111B is an example of a second support member.

[0080] The thermal expansion coefficient of the support member 111B may be a value between the thermal expansion coefficient of the base 101 and the thermal expansion coefficient of the intermediate member 130B, or may be close to or the same as the thermal expansion coefficient of the base 101. In addition, the support member 111B may be configured as a member separate from the base 101 and fixed to the base 101, or may be a part of the base 101.

[0081] [Third embodiment] 8 is a plan view of an optical device 100C of the third embodiment. The optical device 100C of this embodiment differs from the first embodiment in the configuration of the subunit 100a and in the configuration of the support structure 110. Except for these, the optical device 100C has the same configuration as the optical device 100A of the first embodiment.

[0082] Fig. 9 is a side view showing the configuration of subunit 100a1 (100a). As shown in Fig. 9, in subunit 100a1, laser light L output from light-emitting element 32 passes through lens 41C, lens 42C, and lens 43C in this order, and is collimated at least in the Z direction and the Y direction. Lens 41C, lens 42C, and lens 43C are all provided outside housing 20.

[0083] In this embodiment, the lens 41C, the lens 42C, and the lens 43C are arranged in this order in the X1 direction. The laser light L output from the light-emitting element 32 passes through the lens 41C, the lens 42C, and the lens 43C in this order. In addition, the optical axis of the laser light L is linear from the time it leaves the light-emitting element 32 until it passes through the lens 41C, the lens 42C, and the lens 43C, with the fast axis direction of the laser light L aligned along the Z direction and the slow axis direction of the laser light L aligned along the Y direction.

[0084] The lens 41C is slightly spaced from the window member 23 in the X1 direction, or is in contact with the window member 23 in the X1 direction. The lens 41C may be fixed to the housing 20 via an adhesive or the like.

[0085] The laser light L that has passed through the window member 23 is incident on the lens 41C. The lens 41C is a lens having an axially symmetric shape with respect to a central axis Ax along the optical axis, and is configured as a body of revolution about the central axis Ax. The lens 41C is disposed such that the central axis Ax is along the X1 direction and overlaps with the optical axis of the laser light L. The entrance surface 41a and the exit surface 41b of the lens 41C each have a surface of revolution about the central axis Ax that extends in the X1 direction. The exit surface 41b is a convex curved surface that is convex in the X1 direction. The exit surface 41b protrudes more than the entrance surface 41a. The lens 41C is a so-called convex lens.

[0086] The beam width of the laser light L emitted from the lens 41C narrows as it travels in the X1 direction. The beam width is the width of a region in the beam profile of the laser light where the light intensity is equal to or greater than a predetermined value. The predetermined value is, for example, 1 / e of the peak light intensity. 2 The lens 41C focuses the laser light L in the Z direction, the Y direction, and a direction between the Z direction and the Y direction, which has the effect of reducing aberration of the laser light L.

[0087] Lens 42C has a plane-symmetric shape with respect to imaginary center plane Vc2, which is a plane that intersects and is perpendicular to the Z direction. Incident surface 42a and exit surface 42b of lens 42C have cylindrical surfaces that have generatrix along the Y direction and extend in the Y direction. Incident surface 42a is a convex curved surface that is convex in the direction opposite to the X1 direction. Also, exit surface 42b is a concave curved surface that is concave in the X1 direction.

[0088] The lens 42C collimates the laser light L in the Z direction, i.e., in the fast axis, in a state in which the beam width Wzc in the Z direction is smaller than the beam width Wza in the Z direction at the incident surface 41a of the lens 41C. The lens 42C is a concave lens in a cross section perpendicular to the Y direction. The lens 42C may also be referred to as a collimating lens.

[0089] Moreover, the lens 42C is positioned closer to the lens 41C than the focal point Pcz in the Z direction of the laser light L by the lens 41C. If the lens 42C is positioned farther from the lens 41C than the focal point Pcz in the Z direction, the focal point Pcz in the Z direction will appear on the optical path of the laser light L between the lens 41C and the lens 42C. In this case, there is a risk of an inconvenience such as dust accumulating at the focal point Pcz in the Z direction, which has a high energy density. In this respect, in this embodiment, since the lens 42C is positioned closer to the lens 41C than the focal point Pcz in the Z direction, the laser light L is collimated by the lens 42C before reaching the focal point Pcz. That is, according to this embodiment, the focal point Pcz in the Z direction does not appear on the optical path of the laser light L, and therefore, it is possible to avoid the inconvenience caused by the focal point Pcz.

[0090] Although the focal point (not shown) of the laser light L in the Y direction appears between the lens 41C and the lens 42C, the energy density at the focal point in the Y direction is not so high, so that problems such as dust accumulation do not occur.

[0091] The beam width in the Y direction of the laser light L output from the light emitting element 32 and passing through the lenses 41C and 42C increases as it travels in the X1 direction. The laser light L, which is tapered and expands in the Y direction, enters the lens 43C via the lens 42C.

[0092] Lens 43C has a plane-symmetric shape with respect to a virtual center plane that intersects with and is perpendicular to the Y direction. Incident surface 43a and exit surface 43b of lens 43C have cylindrical surfaces that have generatrix along the Z direction and extend in the Z direction. Incident surface 43a is a plane perpendicular to the X1 direction. Also, exit surface 43b is a convex curved surface that is convex in the X1 direction.

[0093] Lens 43C collimates laser light L in the Y direction, i.e., in the slow axis. Lens 43C is a convex lens in a cross section perpendicular to the Z direction. Lens 43C may also be referred to as a collimating lens.

[0094] 8, in this embodiment, the support member 111C supports the condenser lenses 104 and 105. The support member 111C is an intermediate member 130C. The intermediate member 130C is made of a material whose thermal expansion coefficient is between the thermal expansion coefficient of the condenser lenses 104 and 105 and the thermal expansion coefficient of the base 101, and specifically, is made of a copper-tungsten alloy or aluminum oxide.

[0095] In the optical device 100C having such a configuration, the same effect as in the first embodiment can be obtained by providing the intermediate member 130C between the base 101 and the condenser lenses 104 and 105. The intermediate member 130C is an example of a third intermediate member, and the support member 111C is an example of a third support member.

[0096] In the optical device 100C of this embodiment, the number of intermediate members 130C and thus the number of parts of the optical device 100C can be reduced compared to the optical device 100A of the first embodiment and the optical device 100B of the second embodiment, since one intermediate member 130C is provided for each of the two condenser lenses 104 and 105. This may reduce the manufacturing effort and cost, for example. Such a configuration is particularly advantageous when the condenser lenses 104 and 105 are disposed relatively close to each other. On the other hand, when the condenser lenses 104 and 105 are disposed relatively far away from each other, the configuration in which separate intermediate members 130A1 (130B) and 130A2 are provided for each of the condenser lenses 104 and 105, as in the first and second embodiments, may be advantageous in that the intermediate members can be made smaller, and thus an increase in the mass of the optical device 100 can be suppressed.

[0097] [Fourth embodiment] 10 is a plan view of an optical device 100D of a fourth embodiment. The optical device 100D of this embodiment has a similar configuration to the optical device 100 of the above embodiment, except that the light emitting elements 32 output laser beams of different wavelengths (λ1, λ2, . . . , λn-1, λn), the optical device 100D does not have a half-wave plate 108c, and the subassembly 30 is not housed in the housing 20. The interval between the multiple wavelengths is, for example, 5 [nm] to 20 [nm] between the center wavelengths. The light synthesized here may also include a blue laser beam.

[0098] In the optical device 100D having such a configuration, by providing the intermediate member 130C between the base 101 and the condenser lenses 104 and 105, the same effects as in the first embodiment can be obtained.

[0099] [Fifth embodiment] FIG. 11 is a configuration diagram of a light source device 1000 of a fifth embodiment in which the optical device 100 (light emitting device) of any one of the first to fourth embodiments is mounted. The light source device 1000 includes a plurality of optical devices 100 as excitation light sources. Laser light output from the plurality of optical devices 100 is transmitted to a combiner 200 as an optical coupling section via an optical fiber 120. The output ends of the optical fibers 120 are respectively coupled to a plurality of input ports of the combiner 200 with a plurality of inputs and one output. The light source device 1000 is not limited to one including a plurality of optical devices 100, but may include at least one optical device 100.

[0100] [Sixth embodiment] Fig. 12 is a configuration diagram of an optical fiber laser 300 in which the light source device 1000 of Fig. 11 is mounted. The optical fiber laser 300 includes the light source device 1000 and combiner 200 shown in Fig. 11, a rare-earth doped optical fiber 330, and an output-side optical fiber 340. Highly reflective FBGs 310 and 321 (fiber Bragg gratings) are provided at the input end and output end of the rare-earth doped optical fiber 330, respectively.

[0101] An input end of the rare-earth doped optical fiber 330 is connected to the output end of the combiner 200, and an input end of an output-side optical fiber 340 is connected to the output end of the rare-earth doped optical fiber 330. Note that the input section for inputting the laser light output from the plurality of optical devices 100 to the rare-earth doped optical fiber 330 may have another configuration instead of the combiner 200. For example, the optical fibers 120 of the output sections of the plurality of optical devices 100 may be arranged side by side, and the laser light output from the plurality of optical fibers 120 may be input to the input end of the rare-earth doped optical fiber 330 using an input section such as an optical system including a lens. The rare-earth doped optical fiber 330 is an example of an optical amplifying fiber.

[0102] According to the light source device 1000 of the fifth embodiment or the optical fiber laser 300 of the sixth embodiment, by including the optical device 100 of the first to fourth embodiments, the same effects as those of the first to fourth embodiments can be obtained.

[0103] Although the embodiment of the present invention has been illustrated above, the above embodiment is merely an example and is not intended to limit the scope of the invention. The above embodiment can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the gist of the invention. In addition, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be appropriately changed and implemented.

[0104] For example, in the above embodiment, the optical device has two focusing lenses, but is not limited thereto. More specifically, the optical device may have three or more focusing lenses instead of the two focusing lenses, or may have one focusing lens that focuses the laser light toward the end of the optical fiber in both the fast axis and the slow axis.

[0105] In addition, the configurations, arrangements, and combinations of the subunits, the light emitting modules, the optical components, the protrusions, the shielding parts, etc. are not limited to those in the above-described embodiment. In addition, the traveling direction of the stray light is not limited to the above-described direction. [Explanation of symbols]

[0106] 10...Light emitting module 20…Housing 21…Bottom wall 22...Front wall 22a...Opening 23...Window material 30…Sub-assembly 31…Submount 31a…Metallized layer 32...Light emitting element 32a...Emission surface 41C…Lens 41a...Incidence surface 41b...Emission surface 42A, 42C...Lens (optical components) 42a...Incidence surface 42b...Emission surface 43A, 43C...Lens (optical components) 43a...Incidence surface 43b...Emission surface 100,100A~100D…Optical device 100a, 100a1, 100a2...subunits 101...Bass 101b…Surface 101b1...Step 103...Mirror (optical component) 104...Condenser lens (second condenser lens, optical component) 105...Condenser lens (first condenser lens, optical component) 108…Photosynthesis division 108a... combiner (first optical component, optical component) 108b...Mirror (first optical component, optical component) 108c...1 / 2 wavelength plate (first optical component, optical component) 109…Refrigerant passage 109a...Entrance 109b…Exit 110...Support structure 111A to 111C: Support member 111a…side 111b…face 112…Cover 113…End cap 113a1...end face 113b...Protrusion 114…Holder 116...Fixing tool 120...Optical fiber 120a...Peeled end 120a1...Tip 121...Core wire 130A1...Intermediate member (first intermediate member) 130A2...Intermediate member (second intermediate member) 130B...Intermediate member (second intermediate member) 130C...Intermediate member (third intermediate member) 140…Containment room 200…Combiner 300...Optical fiber laser 310,320…High reflective FBG 330...Rare earth doped optical fiber 340...Output optical fiber 1000...Light source device Ax…center axis A1, A2…Array L: Laser light Pcz…Focus point Pth: Threshold R…Containment room Tth: Threshold Vc2: Virtual center plane Wza: Beam width (in Z direction) Wzc…Beam width (collimated in Z direction) X1…direction X2…direction Y...Direction Z…direction

Claims

1. With the base, A plurality of light emitting elements provided on the base and outputting laser light; a plurality of optical components provided on the base and configured to transmit the laser light output from the light-emitting element to an optical fiber; Equipped with The plurality of optical components include a first focusing lens that focuses the laser light from the plurality of light-emitting elements toward an end of the optical fiber; a second condenser lens that condenses the laser light from the plurality of light-emitting elements toward the first condenser lens; Including, the first condenser lens and the second condenser lens are made of synthetic quartz; an intermediate member having a thermal expansion coefficient between the thermal expansion coefficient of the synthetic quartz and the thermal expansion coefficient of the base is provided between the first and second condenser lenses and the base; the first condenser lens and the second condenser lens are each fixed to the intermediate member by an adhesive; a difference between the thermal expansion coefficient of the synthetic quartz and the thermal expansion coefficient of the intermediate member is 11×10 −6 [1 / K] or less; a difference between a thermal expansion coefficient of the intermediate member and a thermal expansion coefficient of the base is 11×10 −6 [1 / K] or less; The optical device, wherein the base is cooled.

2. The optical device as described in claim 1, wherein the plurality of optical components include an optical component that does not have an intermediate member interposed between it and the base.

3. The optical device according to claim 1 , further comprising a first intermediate member interposed between the first focusing lens and the base as the intermediate member.

4. an end cap that is integrated with an end of the optical fiber and has an end face with an area larger than a cross-sectional area of ​​the optical fiber; The optical device according to claim 3 , wherein the first intermediate member is a first support member that is provided on the base and supports the optical fiber, the end cap, and the first focusing lens.

5. a second support member provided on the base and supporting the optical fiber; The optical device according to claim 3 , wherein the first intermediate member is interposed between the second support member and the first focusing lens.

6. 6. The optical device according to claim 3, further comprising a second intermediate member interposed between the second focusing lens and the base as the intermediate member.

7. The optical device according to claim 1 , further comprising, as the intermediate member, a third intermediate member interposed between the first and second condenser lenses and the base.

8. an end cap that is integrated with an end of the optical fiber and has an end face with an area larger than a cross-sectional area of ​​the optical fiber; The optical device according to claim 7 , wherein the third intermediate member is a third support member provided on the base and supporting the optical fiber, the end cap, the first focusing lens, and the second focusing lens.

9. 9. The optical device according to claim 1, wherein the wavelength of the laser light is not less than 400 nm and not more than 520 nm.

10. The optical device according to claim 9 , wherein the absorptance of the first condenser lens and the second condenser lens with respect to the laser light is 0.1% or less.

11. 11. The optical device according to claim 1, wherein the optical output from the optical fiber is 100 W or more.

12. 12. The optical device according to claim 1, wherein the material constituting the intermediate member has a lower absorptance for light having a wavelength of 400 nm or more and 520 nm or less than that of the material constituting the base.

13. The optical device according to any one of claims 1 to 12, wherein the intermediate member is made of a copper-tungsten alloy or an aluminium oxide.

14. An optical device described in any one of claims 1 to 13, wherein the base is provided with a refrigerant passage through which a refrigerant passes that is thermally connected to the intermediate member, the first focusing lens, and the second focusing lens.

15. A light source device comprising the optical device according to any one of claims 1 to 14.

16. The light source device according to claim 15 ; an optical amplifying fiber for amplifying the laser light output from the light source device; An optical fiber laser comprising:

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