Laser module

Abstract

To provide a laser module capable of improving stability of temperature control in the laser module while suppressing enlargement of the laser module.SOLUTION: A laser module 1 comprises a housing 3 which includes a bottom wall 31, on which a mount member 4 is placed, and accommodates a QCL element 2, a diffraction grating unit 5, lens holders 7 and 9 and the mount member 4 therein. The mount member 4 includes: a first loading part 41 where the lens holder 7 is loaded; a second loading part 42 where the QCL element 2 and a temperature sensor T are loaded; a third loading part 43 where the lens holder 9 is loaded; and a fourth loading part 44 where the diffraction grating unit 5 is loaded. At least a second face 42b of the second loading part 42 opposed to the bottom wall 31 is fixed to the bottom wall 31 via a medium M which fills a gap between the second face 42b and the bottom wall 31 and has het conductivity larger than air.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a laser module. [Background technology]

[0002] A known external cavity laser module (hereinafter simply referred to as a "laser module") includes a quantum cascade laser element (hereinafter referred to as a "QCL element"), a diffraction grating unit including a movable diffraction grating, and two lenses arranged on both sides of the QCL element (see, for example, Patent Document 1). In the laser module, a mount member carrying the QCL element, the diffraction grating unit, and two lens holders that hold each of the two lenses is arranged on the bottom wall of a box-shaped housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-44956 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the laser module described above, there is a need to reduce the size of the housing, and there is also a demand for stabilizing temperature control within the laser module in order to increase the reliability of the laser module.

[0005] Therefore, an object of one aspect of the present disclosure is to provide a laser module that can improve the stability of temperature control within the laser module while suppressing an increase in size of the laser module. [Means for solving the problem]

[0006] The present disclosure includes the following laser modules [1] to [8].

[0007] [1] A quantum cascade laser device; A diffraction grating unit including a movable diffraction grating that constitutes an external resonator of the quantum cascade laser element; a first lens holder that is disposed on the opposite side of the quantum cascade laser element from the side on which the movable diffraction grating is located, and that holds a first lens that passes light emitted from the quantum cascade laser element; a second lens holder disposed between the quantum cascade laser element and the movable diffraction grating, holding a second lens that passes the emitted light from the quantum cascade laser element and the light returning from the movable diffraction grating to the quantum cascade laser element; a mount member for mounting the quantum cascade laser element, the diffraction grating unit, the first lens holder, and the second lens holder; a housing having a bottom wall on which the mount member is placed, and accommodating the quantum cascade laser element, the diffraction grating unit, the first lens holder, the second lens holder, and the mount member; the mount member includes a first mounting portion, a second mounting portion, a third mounting portion, and a fourth mounting portion that are arranged in this order from the first lens holder side toward the diffraction grating unit side along a first direction in which the first lens holder and the second lens holder face each other, the first mounting portion has a first mounting surface on which the first lens holder is mounted, and a first surface facing the bottom wall on an opposite side to the first mounting surface, the second mounting portion has a second mounting surface on which the quantum cascade laser element and the temperature sensor are mounted, and a second surface facing the bottom wall on the opposite side to the second mounting surface, the third mounting portion has a third mounting surface on which the second lens holder is mounted, and a third surface facing the bottom wall on an opposite side to the third mounting surface, the fourth mounting portion has a fourth mounting surface on which the diffraction grating unit is mounted, A laser module, wherein at least the second surface is fixed to the bottom wall via a medium having a thermal conductivity greater than that of air filled between the second surface and the bottom wall.

[0008] In the laser module of [1] above, a medium having a thermal conductivity higher than that of air is filled between at least the second surface of the bottom surface (surface facing the bottom wall) of the mount member and the bottom wall, and the mount member (second surface) is fixed to the bottom wall via the medium. By filling the medium directly under the bottom surface (second surface) of the second mounting part on which a quantum cascade laser element (QCL element), which is particularly prone to heat generation, is mounted, it is possible to effectively improve heat dissipation from the second surface to the housing (bottom wall). This makes it possible to stabilize the temperature control in the laser module. In addition, in order to more effectively improve heat dissipation, it is possible to arrange a cooling element such as a Peltier module between the mount member and the bottom wall. However, when such a cooling element is used, not only a space for arranging the cooling element itself but also a space for arranging wiring for the cooling element is required in the housing, which may increase the size of the housing. In the laser module above, the mount member is directly arranged on the bottom wall via the medium filled in the gap between at least the second surface and the bottom wall without using such a cooling element, so that it is possible to suppress the increase in size of the housing. Therefore, according to the laser module, it is possible to improve the stability of temperature control within the laser module while suppressing an increase in size of the laser module.

[0009] [2] The laser module of [1], wherein the medium is formed from a thermosetting resin adhesive.

[0010] According to the above-mentioned configuration [2], by using a resin adhesive as a medium, it is possible to prevent the mounting member from peeling off from the bottom wall due to the difference in thermal expansion between the mounting member and the bottom wall. In addition, since the resin adhesive has a thermosetting property, it is not necessary to provide a space (for example, a gap for admitting light to harden the resin adhesive) that is required when a light-curing resin adhesive is used, and therefore it is possible to reduce the size of the housing.

[0011] [3] The medium is also filled between the first surface and the bottom wall, and between the third surface and the bottom wall, The laser module of [1] or [2], wherein the first surface and the third surface are fixed to the bottom wall via the medium.

[0012] According to the configuration of [3] above, by disposing a medium not only directly under the second mounting section on which the QCL element is mounted (between the second surface and the bottom wall) but also directly under the first mounting section and the third mounting section adjacent to the second mounting section (between the first surface and the third surface and the bottom wall), it is possible to further improve the heat dissipation from the mount member to the bottom wall. As a result, it is possible to further stabilize the temperature control inside the laser module.

[0013] [4] The fourth mounting portion has a fourth surface that faces the bottom wall on the side opposite to the fourth mounting surface and is continuous with the third surface, The medium is also filled between the fourth surface and the bottom wall, The fourth surface is fixed to the bottom wall via the medium.

[0014] According to the above configuration [4], the heat dissipation from the mount member to the bottom wall can be further improved, and the temperature control within the laser module can be further stabilized.

[0015] [5] The housing has a rear wall facing the diffraction grating unit in the first direction and a front wall facing the first lens holder in the first direction, The laser module according to any one of [1] to [4], wherein a distance between the rear wall and the mount member in the first direction is shorter than a distance between the front wall and the mount member in the first direction.

[0016] According to the configuration of [5] above, by arranging the mount member closer to the rear wall than to the front wall, the possibility of the first lens holder coming into contact with the front wall and being damaged can be reduced. In addition, in order to manufacture a laser module, the mount member on which the QCL element and the diffraction grating unit are mounted (fixed) may be placed on the bottom wall, and then the first lens and the second lens may be aligned (i.e., the positions of the first lens holder and the second lens holder relative to the mount member may be adjusted). In such a case, since the distance between the first lens holder and the front wall can be secured, alignment of the first lens becomes easy.

[0017] [6] A laser module according to any one of [1] to [5], wherein a notch extending along an outer edge portion of the bottom surface of the mounting member facing the bottom wall on the rear wall side is provided.

[0018] According to the configuration of [6] above, even if a raised portion such as a weld bead occurs near the connection between the bottom wall and the rear wall of the housing during the manufacture of the laser module, the cutout provided on the outer edge of the bottom surface of the mount member on the rear wall side can avoid or reduce interference between the mount member and the raised portion, making it easy to position the mount member close to the rear wall.

[0019] [7] A notch or a recess is provided on an outer edge of a bottom surface of the mounting member facing the bottom wall, the notch or recess extending along the outer edge, The laser module according to any one of [1] to [6], wherein the medium is disposed in at least a part of a space between the notch or the recess and the bottom wall.

[0020] According to the configuration of [7] above, by fitting a part of the medium into the notch or recess, the fixing strength of the mount member to the bottom wall via the medium can be improved. Also, since the fixing strength can be improved by using the notch or recess in this way, the amount of the medium required to ensure the fixing strength of the mount member to the bottom wall (i.e., the thickness of the medium disposed between the bottom surface (surface including at least the second surface) of the mount member and the bottom wall) can be reduced, and the heat dissipation from the mount member to the bottom wall can be further improved.

[0021] [8] Further comprising an insulating submount disposed on the second mounting surface, The laser module according to any one of [1] to [7], wherein the quantum cascade laser element and the temperature sensor are disposed on the second mounting portion via the submount.

[0022] According to the configuration of [8] above, the QCL element and the temperature sensor can be electrically separated (insulated) by arranging the QCL element and the temperature sensor on an insulating submount. This prevents electrical noise caused by the drive current of the QCL element from being detected by the temperature sensor, and enables highly accurate and stable temperature measurement by the temperature sensor. As a result, more highly stable temperature control of the laser module can be realized based on the measured value of the temperature sensor. In addition, since the QCL element and the temperature sensor can be mounted on the submount to form a unit, pre-inspection of the QCL element and mounting of the QCL element on the mounting member can be facilitated. In addition, since a metal pattern can be formed on the surface of the submount, an electrical connection configuration for supplying a drive current to the QCL element and an electrical connection configuration for acquiring an output signal from the temperature sensor can be easily realized. Effect of the Invention

[0023] According to one aspect of the present disclosure, it is possible to provide a laser module that can improve the stability of temperature control within the laser module while suppressing an increase in size of the laser module. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of a laser module according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the laser module of FIG. 1 at the center in the width direction Y. FIG. [Diagram 3] FIG. 3 is a perspective view of the mount member on which the members other than the first lens holder and the second lens holder are mounted. [Figure 4] FIG. 4A is a diagram showing an example of a notch provided on the outer edge of the bottom surface of the mounting member, and FIG. 4B is a diagram showing an example of a recess provided on the outer edge of the bottom surface of the mounting member. [Diagram 5] FIG. 5 is a plan view showing an example of an electrical connection configuration of a QCL element and a temperature sensor disposed on the second mounting portion of the mounting member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and duplicated descriptions will be omitted. In addition, the terms "upper" and "lower" are used for convenience based on the state shown in the drawings.

[0026] [Overall configuration of the laser module] As shown in FIG. 1 and FIG. 2, the laser module 1 includes a quantum cascade laser element (hereinafter referred to as a "QCL element") 2 and a housing 3 that hermetically houses the QCL element 2. The laser module 1 is a tunable light source in which the wavelength of output light (laser light L) is variable. The laser module 1 can be used, for example, for measuring the absorption spectrum of an analyte having a light absorption band such as glucose in a living body or VOC gas (volatile organic compound). For example, when measuring such an absorption spectrum, the analyte contained in a light-transmitting container is placed between the laser module 1 and a photodetector (not shown). The laser module 1 performs wavelength sweeping in a predetermined wavelength range (for example, mid-infrared region) by changing the wavelength of the output light (laser light L) at high speed. As a result, the absorption spectrum is calculated based on the detection result of the photodetector. The analyte may be any of a gas, a liquid, and a solid.

[0027] The housing 3 contains the QCL element 2, a mount member 4, a diffraction grating unit 5, a lens holder 7 (first lens holder) that holds a lens 6 (first lens), and a lens holder 9 (second lens holder) that holds a lens 8 (second lens). The housing 3 has a bottom wall 31, side walls 32, and a top wall 33. The top wall 33 is not shown in FIG.

[0028] The bottom wall 31 is a rectangular plate-shaped member. The bottom wall 31 is formed of a metal material such as copper tungsten. The mount member 4 is placed on the bottom wall 31. For convenience, in this specification, the longitudinal direction of the bottom wall 31 is referred to as the front-rear direction X (first direction), the short side direction of the bottom wall 31 is referred to as the width direction, and the direction perpendicular to the bottom wall 31 (i.e., the direction perpendicular to both the front-rear direction X and the width direction Y) is referred to as the up-down direction Z. The front-rear direction X is the direction in which the lens holders 7 and 9 face each other. That is, the front-rear direction X is the direction in which the end faces 2a and 2b of the QCL element 2 described later face each other (i.e., the direction perpendicular to the end faces 2a and 2b), and is also the direction along the optical axis of the laser light L emitted from the QCL element 2.

[0029] The side wall 32 is erected on the bottom wall 31. When viewed from the up-down direction Z, the side wall 32 is formed in an annular shape (in this embodiment, a rectangular annular shape) so as to surround the internal space in which the QCL element 2 and the like are housed. In this embodiment, the side wall 32 is formed in a rectangular cylindrical shape. The side wall 32 is formed of a metal material such as Kovar. The side wall 32 is, for example, a Kovar frame plated with Ni / Au. In this embodiment, the side wall 32 is provided in the center in the front-rear direction X. On both sides of the bottom wall 31 in the front-rear direction X, protruding portions 31a are formed so as to protrude outward from the side wall 32. Screw holes 31b are provided in the protruding portions 31a at portions corresponding to the four corners of the bottom wall 31 for attaching the housing 3 (bottom wall 31) to another member.

[0030] The top wall 33 (see FIG. 2) is a member that closes an opening of the side wall 32 on the opposite side to the bottom wall 31. The top wall 33 has a rectangular plate shape. The top wall 33 is formed, for example, from the same metal material (e.g., Kovar) as the side wall 32. The top wall 33 is joined to the end 32a of the side wall 32 on the opposite side to the bottom wall 31 by, for example, seam welding, etc., with the inside of the housing 3 being vacuum or replaced with nitrogen.

[0031] A pair of first side walls 321 extending in the front-rear direction X of the side walls 32 are provided with protruding walls 34 protruding both outside and inside of the first side walls 321. The protruding walls 34 are eaves-shaped members extending along the front-rear direction X above (toward the top wall 33) the center position of the first side walls 321 in the up-down direction Z. A plurality of flat electrode terminals 10 (14 in total, seven on each protruding wall 34 in this embodiment) are arranged on the upper surface of the protruding wall 34 for supplying power to each member (e.g., the QCL element 2, the movable diffraction grating 51 (coil 65), etc.) in the housing 3. Each electrode terminal 10 penetrates the first side wall 321. As shown in FIG. 1, a portion of each electrode terminal 10 located outside the first side wall 321 is electrically connected to a lead pin 11 electrically connected to an external power source. Each electrode terminal 10 is arranged on the upper surface of the protruding wall 34 at approximately equal intervals along the front-rear direction X. The lead pins 11 are arranged at approximately equal intervals along the front-rear direction X on a portion of each electrode terminal 10 located outside the first side wall 321. The portion of each electrode terminal 10 located inside the first side wall 321 is electrically connected to each member inside the housing 3 via a wire (not shown) or the like. With the above configuration, power is supplied from an external power source to each member via the wire (not shown), the electrode terminal 10, and the lead pins 11.

[0032] The second side wall 322 of the side wall 32 extending along the width direction Y has a front side wall 322A facing the lens 6 (lens holder 7) and a rear side wall 322B facing the diffraction grating unit 5. The front side wall 322A is provided with a light exit window 12 that passes the laser light L emitted from one end face 2b of the QCL element 2. The light exit window 12 is formed of, for example, a material (e.g., germanium) that transmits the laser light L with a wavelength in the mid-infrared region. As an example, the light exit window 12 is formed in a disk shape and is fixed to a circular opening formed in the front side wall 322A.

[0033] 2, the laser module 1 includes a mount member 4 on which the QCL element 2, the diffraction grating unit 5, and the lens holders 7 and 9 are mounted within a housing 3. The mount member 4 is made of a material having excellent thermal conductivity, such as copper.

[0034] The mount member 4 is a member that is long in the front-rear direction X. The mount member 4 has a first mounting portion 41, a second mounting portion 42, a third mounting portion 43, and a fourth mounting portion 44. The first mounting portion 41, the second mounting portion 42, the third mounting portion 43, and the fourth mounting portion 44 are arranged in this order along the front-rear direction X from the lens holder 7 side toward the diffraction grating unit 5 side. As shown in FIG. 2 and FIG. 3, the mount member 4 has a pair of side surfaces 4a, 4b that extend along the front-rear direction X (intersecting the width direction Y), a front surface 4c that faces the front wall 322A, a rear surface 4d that faces the rear wall 322B, and a bottom surface 4e that faces the bottom wall 31.

[0035] The first mounting portion 41 has an upper surface 41a (first mounting surface) on which the lens holder 7 is mounted, and a first surface 41b facing the bottom wall 31 on the side opposite to the upper surface 41a.

[0036] The second mounting portion 42 has an upper surface 42a (second mounting surface) on which the QCL element 2 and the temperature sensor T are mounted, and a second surface 42b facing the bottom wall 31 on the side opposite to the upper surface 42a.

[0037] The third mounting portion 43 has an upper surface 43a (third mounting surface) on which the lens holder 9 is mounted, and a third surface 43b facing the bottom wall 31 on the side opposite to the upper surface 43a.

[0038] The fourth mounting portion 44 has an upper surface 44a (fourth mounting surface) on which the diffraction grating unit 5 is mounted, and a fourth surface 44b facing the bottom wall 31 on the side opposite to the upper surface 44a.

[0039] The first surface 41b, the second surface 42b, the third surface 43b, and the fourth surface 44b are provided so as to be continuous with one another and flush with one another, and form a bottom surface 4e of the mount member 4.

[0040] The first mounting portion 41 and the third mounting portion 43 have the same thickness in the vertical direction Z. That is, the height position of the upper surface 41a of the first mounting portion 41 coincides with the height position of the upper surface 43a of the third mounting portion 43 with respect to the bottom surface 4e. The lens holder 7 is bonded and fixed to the upper surface 41a of the first mounting portion 41 via an adhesive layer B1 made of a photocurable resin (e.g., a UV curable resin, etc.). Similarly, the lens holder 9 is bonded and fixed to the upper surface 43a of the third mounting portion 43 via an adhesive layer B2 made of a photocurable resin (e.g., a UV curable resin, etc.).

[0041] The second mounting portion 42 is provided between the first mounting portion 41 and the third mounting portion 43. The second mounting portion 42 is thicker than the first mounting portion 41 and the third mounting portion 43 in the vertical direction Z. That is, the upper surface 42a of the second mounting portion 42 is located higher than the upper surface 41a of the first mounting portion 41 and the upper surface 43a of the third mounting portion 43. The QCL element 2 is fixed to the upper surface 42a of the second mounting portion 42 via the submount 21.

[0042] The submount 21 is an insulating member disposed on the upper surface 42a, and is formed in a plate shape having a predetermined thickness. The submount 21 is formed of, for example, aluminum nitride (AlN). On the submount 21, a temperature sensor T is mounted together with the QCL element 2. The temperature sensor T is, for example, a thermistor. The QCL element 2 and the temperature sensor T are disposed on the second mounting portion 42 via the submount 21.

[0043] The fourth mounting portion 44 is thinner than the first mounting portion 41 and the third mounting portion 43. That is, the upper surface 44a of the fourth mounting portion 44 is located at a lower position than the upper surface 41a of the first mounting portion 41 and the upper surface 43a of the third mounting portion 43. The fourth mounting portion 44 has an arrangement hole 44c that is a non-through hole that opens to the upper surface 44a but does not penetrate to the fourth surface 44b. As shown in FIG. 2, the diffraction grating unit 5 is fixed to the fourth mounting portion 44 using a resin adhesive B3 such as a thermosetting resin with a protrusion 53c that is a part of a yoke 53 described later inserted into the arrangement hole 44c.

[0044] The QCL element 2 has end faces 2a and 2b facing each other in the front-rear direction X. The end face 2a faces the lens 8, and the end face 2b faces the lens 6. The QCL element 2 emits light in the mid-infrared region (for example, 4 μm to 12 μm) from each of the end faces 2a and 2b. The end faces 2a and 2b are flat surfaces (cleavage planes) perpendicular to the front-rear direction X, and the optical axis of the laser light L emitted from the QCL element 2 is along the front-rear direction X. As an example, the QCL element 2 is composed of a semiconductor substrate and a semiconductor layer (a layer structure including an active layer described later) stacked on the semiconductor substrate. In this embodiment, the QCL element 2 is disposed on the submount 21 such that the semiconductor substrate is located below and the semiconductor layer is located above. The semiconductor layer included in the QCL element 2 has a laminated structure including, for example, an active layer made of multiple quantum well layers (e.g., InGaAs) and multiple quantum barrier layers (e.g., InAlAs), and a pair of clad layers (e.g., InP) arranged on both sides of the active layer with the active layer in between. In this embodiment, the lamination direction of the laminated structure coincides with the vertical direction Z. Note that the QCL element 2 may include multiple active layers and a pair of clad layers having different center wavelengths, and even in this case, it is possible to emit light in a wide band as described above. The end face 2a may be coated with an anti-reflective coating, and the end face 2b functioning as a resonator surface may be coated with a low-reflective coating.

[0045] The lens 6 is disposed on the opposite side of the QCL element 2 from the side where the movable diffraction grating 51 (diffraction grating unit 5) is located. That is, the lens 6 is disposed at a position facing the end face 2b of the QCL element 2. The lens 6 is, for example, an aspheric lens made of zinc selenide (ZnSe). The surface of the lens 6 may be provided with an anti-reflective coating. The lens 6 passes the light L3 emitted from the QCL element 2 (end face 2b). For example, the lens 6 collimates the light L3. The light L3 collimated by the lens 6 passes through the light exit window 12 and is output to the outside as output light (laser light L).

[0046] The lens 8 is disposed between the end face 2a of the QCL element 2 and the movable diffraction grating 51 (diffraction grating unit 5). That is, the lens 8 is disposed at a position facing the end face 2a of the QCL element 2. As an example, the lens 8 is formed of chalcogenide glass, and has a portion in the center that functions as a short-focus microlens with a diameter of several mm or less. The lens 8 passes light L1 emitted from the end face 2a of the QCL element 2 and light L2 returning from the movable diffraction grating 51 to the QCL element 2. The lens 8 collimates the light L1.

[0047] The lens holders 7 and 9 have a substantially rectangular parallelepiped outer shape. The lens holders 7 and 9 are provided in a cylindrical shape that surrounds the side surfaces of the lenses 6 and 8. The lenses 6 and 8 are supported (held) by the lens holders 7 and 9 with a resin adhesive or the like.

[0048] The diffraction grating unit 5 includes a movable diffraction grating 51, a magnet 52, and a yoke 53. The movable diffraction grating 51 is formed in a substantially plate shape. The magnet 52 is disposed on the opposite side of the movable diffraction grating 51 to the QCL element 2. The movable diffraction grating 51 is fixed to the yoke 53, and the magnet 52 is housed within the yoke 53. The movable diffraction grating 51, the magnet 52, and the yoke 53 are integrated together to form a single unit.

[0049] The light L1 collimated by the lens 8 is incident on the movable diffraction grating 51 of the diffraction grating unit 5. The movable diffraction grating 51 diffracts and reflects the incident light L1, thereby returning a part of the light L1 (light L2 of a specific wavelength) to the end face 2a of the QCL element 2 via the lens 8. That is, the movable diffraction grating 51 constitutes an external resonator for the light L1 emitted from the end face 2a of the QCL element 2. In this embodiment, the movable diffraction grating 51 and the end face 2b of the QCL element 2 constitute a Littrow-type external resonator. This allows the laser module 1 to amplify the light L2 of a specific wavelength and output it to the outside as output light (laser light L).

[0050] In addition, in the movable diffraction grating 51, the orientation of the diffraction grating portion 64 that diffracts and reflects the incident light L1 can be changed at high speed. This makes it possible to change the wavelength of the light L2 that returns from the movable diffraction grating 51 to the end face 2a of the QCL element 2, and therefore makes it possible to change the wavelength of the output light (laser light L) of the laser module 1.

[0051] 3, the movable diffraction grating 51 includes a support portion 61, a pair of connecting portions 62, a movable portion 63, a diffraction grating portion 64, and a coil 65. The movable diffraction grating 51 is configured as a MEMS device that swings (rotates) the movable portion 63 around an axis A. A MEMS device is a device formed using microfabrication technology (patterning, etching, etc.) called MEMS technology, and includes semiconductor devices formed using semiconductor microfabrication technology.

[0052] The support part 61 is a flat frame body having a rectangular shape in a plan view. The support part 61 supports the movable part 63 via a pair of connecting parts 62. Each connecting part 62 is a flat member having a rectangular rod shape in a plan view, and extends along the axis A while being bent, for example. Each connecting part 62 connects the movable part 63 to the support part 61 on the axis A so that the movable part 63 can swing freely around the axis A. The movable part 63 is located inside the support part 61. The movable part 63 can swing around the axis A as described above. The support part 61, the connecting parts 62, and the movable part 63 are integrally formed, for example, by being built into one SOI (Silicon on Insulator) substrate.

[0053] A diffraction grating section 64 is provided on the surface of the movable section 63 facing the QCL element 2. The diffraction grating section 64 has a plurality of grating grooves (not shown) and diffracts and reflects the light L1 emitted from the QCL element 2. The diffraction grating section 64 includes, for example, a resin layer provided on the surface of the movable section 63 and having a diffraction grating pattern formed thereon, and a metal layer provided over the surface of the resin layer so as to follow the diffraction grating pattern. Alternatively, the diffraction grating section 64 may be formed only by a metal layer provided on the movable section 63 and having a diffraction grating pattern formed thereon. As the diffraction grating pattern, for example, in addition to a blazed grating having a sawtooth cross section as in this embodiment, a binary grating having a rectangular cross section, a holographic grating having a sinusoidal cross section, or the like can be used. The diffraction grating pattern is formed in the resin layer by, for example, nanoimprint lithography. The metal layer is, for example, a metal reflective film made of gold, and is formed by vapor deposition.

[0054] The coil 65 is made of a metal material such as copper, and has a damascene structure embedded in a groove formed in the surface of the movable part 63. The coil 65 is a drive coil that passes a current for driving the movable diffraction grating 51 (i.e., for oscillating the movable part 63).

[0055] The magnet 52 generates a magnetic field (magnetic force) that acts on the coil 65. The magnet 52 is, for example, a neodymium magnet (permanent magnet) formed in a substantially rectangular parallelepiped shape.

[0056] The yoke 53 amplifies the magnetic force of the magnet 52 and forms a magnetic circuit together with the magnet 52. The yoke 53 has an inclined surface 53a, a lower surface 53b, a protruding portion 53c, and a positioning surface 53d.

[0057] As shown in FIG. 2, the inclined surface 53a is inclined with respect to the end surface 2a of the QCL element 2. By fixing the movable diffraction grating 51 on such an inclined surface 53a, the normal N of the diffraction grating portion 64 of the movable diffraction grating 51 can be inclined with respect to the end surface 2a. In this example, the diffraction grating portion 64 is inclined so as to face one side (top wall 33 side) in the vertical direction Z, but the diffraction grating portion 64 may be inclined so as to face the other side (bottom wall 31 side) in the vertical direction Z. The inclination angle of the inclined surface 53a (i.e., the angle θ1 of the normal N with respect to the front-rear direction X when viewed from the width direction Y) is set according to the oscillation wavelength of the QCL element 2, the number of grooves of the grating grooves in the diffraction grating portion 64, the blazed angle, and the like. For example, when the oscillation wavelength is in the 7 μm band and the number of grooves is 150 / mm, the angle θ1 is set to about 30 degrees.

[0058] The yoke 53 is formed in a substantially U-shape (inverted C-shape) when viewed from the width direction Y, and defines an arrangement space SP that opens to an inclined surface 53a. The magnet 52 is disposed in this arrangement space SP, and the magnet 52 is housed in the yoke 53. When viewed from the width direction Y, the yoke 53 surrounds the magnet 52. The movable diffraction grating 51 is fixed to the inclined surface 53a at the edge of the support portion 61 so as to cover the opening of the arrangement space SP.

[0059] The lower surface 53b faces the upper surface 44a of the fourth mounting portion 44. The lower surface 53b is provided with a protruding portion 53c that protrudes downward. The positioning surface 53d is perpendicular to the front-rear direction X so as to connect the inclined surface 53a and the lower surface 53b. The positioning surface 53d abuts against the side surface 43c of the third mounting portion 43 (a surface perpendicular to the front-rear direction X that connects the upper surface 43a of the third mounting portion 43 and the upper surface 44a of the fourth mounting portion 44). This allows the diffraction grating unit 5 to be positioned in the front-rear direction X.

[0060] In the movable diffraction grating 51, when a current flows through the coil 65, a Lorentz force is generated in a predetermined direction on the electrons flowing through the coil 65 due to the magnetic field formed by the magnet 52 and the yoke 53. As a result, the coil 65 receives a force in a predetermined direction. Therefore, by controlling the direction or magnitude of the current flowing through the coil 65, the movable part 63 (diffraction grating part 64) can be swung around the axis A. In addition, by passing a current of a frequency corresponding to the resonant frequency of the movable part 63 through the coil 65, the movable part 63 can be swung at high speed at the resonant frequency level (for example, at a frequency of 1 kHz or more). In this way, the coil 65, the magnet 52, and the yoke 53 function as an actuator part that swung the movable part 63.

[0061] [Mounting component details] 2, the bottom surface 4e of the mounting member 4 is fixed to the bottom wall 31 via a medium M filled between the bottom surface 4e and the bottom wall 31. The medium M is made of a material having a higher thermal conductivity than air. As an example, the medium M is made of a thermosetting resin adhesive.

[0062] As shown in FIG. 2, the distance d1 in the front-rear direction X between the rear wall 322B and the mount member 4 (fourth mounting portion 44) is shorter than the distance d2 in the front-rear direction X between the front wall 322A and the mount member 4 (first mounting portion 41).

[0063] As shown in Figures 3 and 4A, the outer edge of the bottom surface 4e of the mounting member 4 is provided with notches G1, G2, and G3 (notch grooves) extending along the outer edge. In this embodiment, the outer edge of the bottom surface 4e on the side surface 4a side is provided with a notch G1 extending in the front-rear direction X. The outer edge of the bottom surface 4e on the side surface 4b side is provided with a notch G2 extending in the front-rear direction X. The outer edge of the bottom surface 4e on the rear surface 4d side is provided with a notch G3 (see Figures 2 and 3) extending in the width direction Y. No notch is provided on the outer edge of the bottom surface 4e on the front surface 4c side.

[0064] Here, the medium M is disposed in at least a part of the space between the notches G1, G2, G3 and the bottom wall 31. In this embodiment, a resin pool consisting of a part of the medium M is formed in at least a part of the space between the notches G1, G2, G3 and the bottom wall 31. For example, during the manufacture of the laser module 1, the medium M is applied onto the bottom wall 31 or onto the bottom surface 4e of the mount member 4, and the mount member 4 is pressed against the bottom wall 31, whereby the medium M is compressed in the up-down direction Z and stretched in the front-rear direction X or width direction Y. As a result, a part of the medium M protrudes (escapes) into the space between the notches G1, G2, G3 and the bottom wall 31. The part of the medium M protruding in this way forms the above-mentioned resin pool.

[0065] Note that a recess (recess groove) may be formed in the outer edge of the bottom surface 4e of the mounting member 4 instead of the above-mentioned notches G1, G2, and G3. For example, as shown in Fig. 4B, a recess Ga may be provided in the outer edge of the bottom surface 4e on the side surface 4a side, extending in the front-rear direction X on the inner side of a corner where the bottom surface 4e and the side surface 4a intersect. Similarly, a recess Gb may be provided in the outer edge of the bottom surface 4e on the side surface 4b side, extending in the front-rear direction X on the inner side of a corner where the bottom surface 4e and the side surface 4b intersect.

[0066] [Electrical connection configuration of QCL element and temperature sensor] As shown in FIG. 3 and FIG. 5, three metal patterns 22, 23, 24 (metal thin films) separated from each other are formed on the submount 21. The metal pattern 22 includes a portion exposed on one side of the QCL element 2 in the width direction Y (the side opposite to the side where the temperature sensor T is arranged) and a portion arranged below the QCL element 2 and in contact with the QCL element 2 (for example, the surface opposite to the semiconductor layer side of the semiconductor substrate). The metal pattern 22 functions as a cathode electrode of the QCL element 2. The metal pattern 23 includes a portion exposed on one side of the QCL element 2 in the width direction Y (the side opposite to the side where the temperature sensor T is arranged). The metal pattern 24 includes a portion exposed on the other side of the QCL element 2 in the width direction Y (the side where the temperature sensor T is arranged) and a portion arranged below the temperature sensor T and in contact with the temperature sensor T. The metal pattern 24 functions as one electrode (positive or negative electrode) connected to the temperature sensor T.

[0067] The laser module 1 has metal wirings W1, W21, W22, W3, and W4 each consisting of one or more wires. As an example, each of the metal wirings W1 and W21 consists of four wire groups, the metal wiring W22 consists of six wire groups, and each of the metal wirings W3 and W4 consists of two wire groups.

[0068] One end of the metal wiring W1 is connected to one electrode terminal 10a located on one side of the QCL element 2 in the width direction Y. The other end of the metal wiring W1 is connected to the metal pattern 22. One end of the metal wiring W21 is connected to another electrode terminal 10b located on one side of the QCL element 2 in the width direction Y. The other end of the metal wiring W21 is connected to the metal pattern 23. One end of the metal wiring W22 is connected to the metal pattern 23. The other end of the metal wiring W22 is connected to an anode electrode of the QCL element 2 (for example, an electrode provided on a semiconductor layer). The lead pins 11 (each lead pin 11 corresponding to the electrode terminals 10a and 10b), the electrode terminals 10a and 10b, the metal wirings W1, W21, and W22, and the metal patterns 22 and 23 realize an electrical connection configuration (current path) for supplying a drive current from an external power source to the QCL element 2.

[0069] One end of the metal wiring W3 is connected to one electrode terminal 10c located on the other side of the QCL element 2 in the width direction Y. The other end of the metal wiring W3 is connected to the metal pattern 24. One end of the metal wiring W4 is connected to another electrode terminal 10d located on the other side of the QCL element 2 in the width direction Y. The other end of the metal wiring W4 is connected to the other electrode of the temperature sensor T. The lead pins 11 (each lead pin 11 corresponding to the electrode terminals 10c and 10d), the electrode terminals 10c and 10d, the metal wirings W3 and W4, and the metal pattern 24 realize an electrical connection configuration (current path) for acquiring an output signal of the temperature sensor T (e.g., a resistance change of the temperature sensor T).

[0070] [Effects of this embodiment] In the laser module 1 described above, a medium M having a thermal conductivity higher than that of air is filled between at least the second surface 42b of the bottom surface 4e of the mount member 4 and the bottom wall 31, and the mount member 4 (second surface 42b) is fixed to the bottom wall 31 via the medium M. By filling the medium M directly under the bottom surface (second surface 42b) of the second mounting portion 42 on which the QCL element 2, which is particularly prone to heat generation, is mounted, it is possible to effectively improve the heat dissipation from the second surface 42b to the housing 3 (bottom wall 31). This makes it possible to stabilize the temperature control in the laser module 1. More specifically, even if the temperature in the laser module 1 rises, the heat can be suitably dissipated from the second surface 42b to the housing 3, so that it is possible to suppress the temperature in the laser module 1 from rising too much and to keep the temperature in the laser module 1 within a certain range.

[0071] In order to more effectively improve the heat dissipation, it is possible to arrange a cooling element such as a Peltier module between the mount member 4 (bottom surface 4e) and the bottom wall 31. However, when such a cooling element is used, not only a space for arranging the cooling element itself but also a space for arranging wiring for the cooling element is required in the housing 3, so that the housing 3 may become large. In the laser module 1, the mount member 4 is directly arranged on the bottom wall 31 via the medium M filled in at least the gap between the second surface 42b and the bottom wall 31 without using such a cooling element, so that the housing 3 can be prevented from becoming large. Therefore, according to the laser module 1, it is possible to improve the stability of the temperature control in the laser module 1 while preventing the laser module 1 from becoming large.

[0072] The medium M is made of a thermosetting resin adhesive. According to the above configuration, by using a resin adhesive as the medium M, it is possible to prevent the mount member 4 from peeling off from the bottom wall 31 due to a difference in thermal expansion between the mount member 4 and the bottom wall 31. In addition, since the resin adhesive has thermosetting properties, it is not necessary to provide a space (for example, a gap for admitting light to harden the resin adhesive) that is required when a light-curing resin adhesive is used, and therefore the housing 3 can be made smaller.

[0073] 2, the medium M is also filled between the first surface 41b and the third surface 43b and the bottom wall 31, and the first surface 41b and the third surface 43b are fixed to the bottom wall 31 via the medium M. According to the above configuration, the medium M is disposed not only directly below the second mounting portion 42 on which the QCL element 2 is mounted (between the second surface 42b and the bottom wall 31) but also directly below the first mounting portion 41 and the third mounting portion 43 adjacent to the second mounting portion 42 (between the first surface 41b and the third surface 43b and the bottom wall 31), thereby further improving the heat dissipation from the mount member 4 to the bottom wall 31. As a result, the temperature control in the laser module 1 can be further stabilized.

[0074] 2, the medium M is also filled between the bottom wall 31 and a fourth surface 44b provided continuously with the third surface 43b, and the fourth surface 44b is fixed to the bottom wall 31 via the medium M. According to the above configuration, it is possible to further improve the heat dissipation from the mount member 4 to the bottom wall 31, and therefore it is possible to further stabilize the temperature control inside the laser module 1.

[0075] Incidentally, as a method for fixing the fourth mounting portion 44 to the bottom wall 31, a method of fixing the fourth mounting portion 44 and the diffraction grating unit 5 (protrusion 53c) together to the bottom wall 31 through a resin adhesive B3 filled in the placement hole 44c by making the placement hole 44c penetrate in the vertical direction Z is also conceivable. However, when configured in such a manner, a problem may occur in that the fourth mounting portion 44 and the diffraction grating unit 5 (protrusion 53c) are likely to be peeled off from the bottom wall 31 due to voids generated in the resin adhesive B3. On the other hand, as shown in FIG. 2, by adopting a configuration in which the placement hole 44c is configured as a non-through hole, a fourth surface 44b facing the bottom wall 31 is formed on the entire lower surface of the fourth mounting portion 44, and the fourth surface 44b is fixed to the bottom wall 31 via a medium M, it is possible to avoid the occurrence of the above problems.

[0076] As shown in FIG. 2, in the front-rear direction X, the distance d1 between the rear side wall 322B and the mount member 4 is shorter than the distance d2 between the front side wall 322A and the mount member 4. According to the above configuration, by arranging the mount member 4 closer to the rear side wall 322B than the front side wall 322A, the possibility that the lens holder 7 (or the surface on the light-emitting window 12 side of the lens 6 held by the lens holder 7) comes into contact with the front side wall 322A and is damaged can be reduced. Further, in order to manufacture the laser module 1, after placing the mount member 4 on which the QCL element 2 and the diffraction grating unit 5 are mounted (fixed) on the bottom wall 31, alignment of the lenses 6 and 8 (that is, position adjustment of the lens holders 7 and 9 with respect to the mount member 4) may be performed. In such a case, according to the above configuration (that is, the configuration in which the mount member 4 is arranged in the housing 3 so that "d1 < d2" is satisfied), since the distance between the lens holder 7 and the front side wall 322A can be ensured, alignment of the lens 6 (position adjustment of the lens holder 7 with respect to the mount member 4) becomes easy.

[0077] 2 and 3, a notch G3 is provided on the outer edge of the bottom surface 4e of the mount member 4 on the rear side wall 322B side, the notch G3 extending along the outer edge in the width direction Y. According to the above configuration, even if a raised portion such as a weld bead occurs near the connection portion between the bottom wall 31 of the housing 3 and the rear side wall 322B during the manufacture of the laser module 1, the notch G3 provided on the outer edge of the bottom surface 4e (fourth surface 44b) of the mount member 4 on the rear side wall 322B side can avoid or reduce interference between the mount member 4 and the raised portion. This makes it easy to arrange the mount member 4 close to the rear side wall 322B.

[0078] As shown in FIG. 2, FIG. 3, and FIG. 4A, the outer edge of the bottom surface 4e of the mount member 4 (in this embodiment, all outer edges except the outer edge on the front surface 4c side) is provided with notches G1, G2, and G3 extending along the outer edge. In addition, the medium M is disposed in at least a part of the space between the notches G1, G2, and G3 and the bottom wall 31. According to the above-mentioned configuration, by making a part of the medium M enter the notches G1, G2, and G3, the fixing strength of the mount member 4 to the bottom wall 31 via the medium M can be improved. For example, by forming the above-mentioned resin pool in the space between the notches G1, G2, and G3 and the bottom wall 31, the fixing strength of the mount member 4 to the bottom wall 31 can be increased. Furthermore, by utilizing the cutouts G1, G2, and G3 (in other words, the portion of the medium M that enters the space formed by the cutouts G1, G2, and G3) in this manner to improve the fixing strength, the amount of medium M required to ensure the fixing strength of the mounting member 4 to the bottom wall 31 (i.e., the thickness of the medium M between the bottom surface 4e of the mounting member 4 and the bottom wall 31) can be reduced, thereby further improving the heat dissipation from the mounting member 4 to the bottom wall 31.

[0079] As shown in Fig. 4B, the same effect as above can be obtained by forming recesses Ga, Gb instead of the notches G1, G2. However, from the viewpoint of increasing the fixing strength between the bottom surface 4e and the bottom wall 31 by making as large an area as possible of the continuous region where the bottom surface 4e and the bottom wall 31 are fixed via the medium M, it is preferable that the recesses Ga, Gb are provided as close as possible to the outer end of the bottom surface 4e. From this viewpoint, it is preferable that the notches G1, G2 are provided at the outer end of the bottom surface 4e rather than the recesses Ga, Gb.

[0080] As shown in FIG. 2 and FIG. 3, an insulating submount 21 is disposed on the upper surface 42a of the second mounting portion 42. The QCL element 2 and the temperature sensor T are disposed on the second mounting portion 42 via the submount 21. According to the above configuration, the QCL element 2 and the temperature sensor T are disposed on the insulating submount 21, so that the QCL element 2 and the temperature sensor T can be electrically separated (insulated). This prevents electrical noise caused by the driving current of the QCL element 2 from being detected by the temperature sensor T, and enables highly accurate and stable temperature measurement by the temperature sensor T. As a result, more highly stable temperature control of the laser module 1 (for example, cooling control of the housing 3 to lower the temperature inside the laser module 1) can be realized based on the measurement value of the temperature sensor T. In addition, since the QCL element 2 and the temperature sensor T can be mounted on the submount 21 to be unitized, it is possible to facilitate pre-inspection of the QCL element 2 and mounting of the QCL element 2 on the mounting member 4. 3 and 5, the metal patterns 22, 23, and 24 can be formed on the surface of the submount 21, so that an electrical connection configuration for supplying a drive current to the QCL element 2 and an electrical connection configuration for acquiring an output signal from the temperature sensor T can be easily realized. In addition, the QCL element 2 (semiconductor substrate) and the temperature sensor T are reliably insulated by the insulating submount 21, so that the degree of freedom in selecting the material of the adhesive for bonding each of the QCL element 2 and the temperature sensor T to the submount 21 can be improved. That is, since the QCL element 2 and the temperature sensor T can be insulated by the submount 21, it is not necessary to use an insulating adhesive for insulating the QCL element 2 and the temperature sensor T. As a result, it is possible to bond each of the QCL element 2 and the temperature sensor T to the submount 21 using an adhesive with high thermal conductivity, regardless of whether it is insulating or conductive. This effectively improves the heat dissipation from the QCL element 2 and the temperature sensor T to the housing 3 (bottom wall 31) via the submount 21 and the mounting member 4.

[0081] [Variations] The present disclosure is not limited to the above embodiment. The material and shape of each component are not limited to the above-mentioned material and shape, and various materials and shapes can be adopted. In addition, some components included in the laser module 1 according to the above embodiment may be omitted or changed as appropriate. For example, in the above embodiment, some characteristic components included in the laser module 1 and some effects exerted by each component are described, but the laser module according to the present disclosure does not necessarily need to be configured to exert all the effects described in the above embodiment, and may be configured to exert only some of the effects described in the above embodiment. In the latter case, the laser module only needs to have a configuration essential for exerting at least the part of the effect, and a configuration that is not essential for exerting the part of the effect may be omitted or changed as appropriate.

[0082] For example, the medium M may be disposed only between a portion of the bottom surface 4e (at least a portion of an area including the second surface 42b) and the bottom wall 31. However, by disposing the medium M between the entire bottom surface 4e and the bottom wall 31 as in this embodiment, it is possible to effectively improve the heat dissipation from the mount member 4 to the bottom wall 31.

[0083] In addition, the position and shape of the above-mentioned notch or recess are not limited to the examples shown in (A) and (B) of FIG. 4. In the example of (A) of FIG. 4, the notch G1 is formed in a triangular cross section, but may be formed in a rectangular cross section, for example. In addition, each of the notches G1, G2, and G3 may be omitted, or a notch or recess may be provided on the outer edge of the front surface 4c side of the bottom surface 4e. However, as in this embodiment, by providing the notches G1 and G2 along the longitudinal direction X, which is the longitudinal direction, resin pools extending long in the longitudinal direction X along the notches G1 and G2 can be formed on both sides of the width direction Y, and therefore the fixing strength of the mount member 4 to the bottom wall 31 can be effectively improved. [Explanation of symbols]

[0084] REFERENCE SIGNS LIST 1...laser module, 2...QCL element (quantum cascade laser element), 3...housing, 4...mounting member, 4e...bottom surface, 5...diffraction grating unit, 6...lens (first lens), 7...lens holder (first lens holder), 8...lens (second lens), 9...lens holder (second lens holder), 21...submount, 31...bottom wall, 41...first mounting portion, 41a...top surface (first mounting surface) , 41b...first surface, 42...second mounting portion, 42a...top surface (second mounting surface), 42b...second surface, 43...third mounting portion, 43a...top surface (third mounting surface), 43b...third surface, 44...fourth mounting portion, 44a...top surface (fourth mounting surface), 44b...fourth surface, 51...movable diffraction grating, 322A...front wall, 322B...rear wall, G1, G2, G3...notches, Ga, Gb...recess, M...medium, T...temperature sensor.

Claims

1. A quantum cascade laser element, a diffraction grating unit including a movable diffraction grating that constitutes an external resonator of the quantum cascade laser element, a first lens holder disposed on the side opposite to the side where the movable diffraction grating is located with respect to the quantum cascade laser element, and holding a first lens that allows the emitted light from the quantum cascade laser element to pass therethrough, a second lens holder disposed between the quantum cascade laser element and the movable diffraction grating, and holding a second lens that allows the emitted light from the quantum cascade laser element and the light that is returned from the movable diffraction grating to the quantum cascade laser element to pass therethrough, a mount member on which the quantum cascade laser element, the diffraction grating unit, the first lens holder, and the second lens holder are mounted, a housing having a bottom wall on which the mount member is placed, and housing the quantum cascade laser element, the diffraction grating unit, the first lens holder, the second lens holder, and the mount member, The mount member has a first mounting portion, a second mounting portion, a third mounting portion, and a fourth mounting portion that are sequentially arranged from the first lens holder side toward the diffraction grating unit side along a first direction in which the first lens holder and the second lens holder face each other, The first mounting portion has a first mounting surface on which the first lens holder is mounted and a first surface that faces the bottom wall on the side opposite to the first mounting surface, The second mounting portion has a second mounting surface on which the quantum cascade laser element and a temperature sensor are mounted and a second surface that faces the bottom wall on the side opposite to the second mounting surface, The third mounting portion has a third mounting surface on which the second lens holder is mounted and a third surface that faces the bottom wall on the side opposite to the third mounting surface, The fourth mounting portion has a fourth mounting surface on which the diffraction grating unit is mounted, At least the second surface is fixed to the bottom wall via a medium having a thermal conductivity greater than that of the air filled between the second surface and the bottom wall, A laser module.

2. The laser module according to claim 1, wherein the medium is formed of a thermosetting resin adhesive.

3. The medium is also filled between the first surface and the third surface and the bottom wall, The laser module according to claim 1, wherein the first surface and the third surface are fixed to the bottom wall via the medium.

4. The fourth mounting portion has a fourth surface that faces the bottom wall on the side opposite to the fourth mounting surface and is continuous with the third surface. The medium is also filled between the fourth surface and the bottom wall. The fourth surface is fixed to the bottom wall via the medium. The laser module according to claim 1.

5. The housing has a rear wall that faces the diffraction grating unit in the first direction and a front wall that faces the first lens holder in the first direction. The distance between the rear wall and the mount member in the first direction is shorter than the distance between the front wall and the mount member in the first direction. The laser module according to claim 1.

6. An outer edge portion on the rear wall side of the bottom surface of the mount member facing the bottom wall is provided with a notch extending along the outer edge portion. The laser module according to claim 5.

7. An outer edge portion of the bottom surface of the mount member facing the bottom wall is provided with a notch or a recess extending along the outer edge portion. The medium is disposed in at least a part of the space between the notch or the recess and the bottom wall. The laser module according to claim 1.

8. The laser module further includes an insulating submount disposed on the second mounting surface. The quantum cascade laser element and the temperature sensor are disposed on the second mounting portion via the submount. The laser module according to claim 1.

Images