Optical module

Abstract

The optical module comprises a first laser diode, a second laser diode, a third laser diode, a first submount on which the first laser diode is mounted, a second submount on which the second laser diode is mounted, a third submount on which the third laser diode is mounted, a base submount having a first surface on which the first submount, second submount, and third submount are attached, a first filter for combining the first light and the second light, a second filter for combining the first combined light and the third light, and a cap provided with an output window that transmits the second combined light combined by the second filter. When the second combined light is converted into collimated light by a lens provided on the outside of the cap, the ellipticity of the second combined light is 0.9 or greater.

Description

Technical Field

[0001] The present disclosure relates to an optical module. This application claims priority based on Japanese Application No. 2024-192398 filed on October 31, 2024, and incorporates all the descriptions set forth in the Japanese application.

Background Art

[0002] An optical module including a plurality of semiconductor light-emitting elements and a filter that directly receives the emitted light from the plurality of semiconductor light-emitting elements and combines them coaxially is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] An optical module in accordance with this disclosure includes a first laser diode that emits a first light, a second laser diode that emits a second light, a third laser diode that emits a third light, a first submount on which the first laser diode is mounted, a second submount on which the second laser diode is mounted, a third submount on which the third laser diode is mounted, a base submount having a first surface to which the first submount, the second submount and the third submount are mounted, and a device that transmits the first light and reflects the second light. The system comprises a first filter that combines the first and second beams of light, a second filter that transmits the first combined beam of light combined by the first filter and reflects the third beam of light, thereby combining the first combined beam of light and the third beam of light, and a cap that is attached to cover the first laser diode, second laser diode, third laser diode, first submount, second submount, third submount, first filter, second filter, and base submount, and has an output window that transmits the second combined beam of light combined by the second filter. When the second combined beam of light is converted into collimated light by a lens provided on the outside of the cap, the ellipticity of the second combined beam of light is 0.9 or greater. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 is an external perspective view of the optical module according to Embodiment 1. [Figure 2] Figure 2 is an external perspective view of the optical module according to Embodiment 1. [Figure 3] Figure 3 is a schematic plan view showing the structure of the optical module shown in Figure 2. [Figure 4] Figure 4 is a schematic front view of the optical module shown in Figure 2. [Figure 5] Figure 5 is a schematic side view of the optical module shown in Figure 2. [Figure 6] Figure 6 is an exploded perspective view of the optical module shown in Figure 2. [Figure 7]Figure 7 is a schematic perspective view showing the base submount, first submount, second submount, third submount, first laser diode, second laser diode, and third laser diode included in the optical module shown in Figure 2, before they are fixed in place. [Figure 8] Figure 8 is a flowchart showing a typical process in the manufacturing method of the optical module in Embodiment 1. [Figure 9] Figure 9 is an external perspective view of the optical module used with the lens. [Figure 10] Figure 10 is a graph of the simulation results showing the relationship between lens position and beam diameter. [Figure 11] Figure 11 is a graph showing the simulation results illustrating the relationship between lens position and beam diameter. [Figure 12] Figure 12 is a graph showing the simulation results illustrating the relationship between lens position and beam diameter. [Figure 13] Figure 13 is a table showing the relationship between beam diameter and ellipticity in Figures 10, 11, and 12. [Figure 14] Figure 14 is an external perspective view of the optical module according to Embodiment 2. [Figure 15] Figure 15 is an external perspective view of the optical module according to Embodiment 2. [Figure 16] Figure 16 is a schematic plan view showing the structure of the optical module shown in Figure 15. [Figure 17] Figure 17 is a schematic front view of the optical module shown in Figure 15. [Figure 18] Figure 18 is a schematic side view of the optical module shown in Figure 15. [Figure 19] Figure 19 is a schematic perspective view showing the state in which the base submount is fixed to the base portion of the optical module in Embodiment 2. [Figure 20] Figure 20 is an external perspective view of the optical module used with the lens. [Modes for carrying out the invention]

[0006] Recently, there has been a demand for miniaturization and compact device configurations in optical modules that use laser diodes as light sources and emit combined red, green, and blue light. Furthermore, there is a need for the shape of the beam emitted from the combined red, green, and blue light to be as close to a perfect circle as possible, while keeping the beam diameter from becoming too large. This requirement is particularly high when using the optical module as a laser beam scanner, in order to improve image quality.

[0007] Therefore, one of the objectives is to provide an optical module that can easily obtain a desired beam shape while achieving miniaturization and a compact device configuration.

[0008] Such optical modules make it easy to obtain the desired beam shape while miniaturizing the device and streamlining its configuration.

[0009] (1) The optical module according to the present disclosure includes a first laser diode that emits a first light, a second laser diode that emits a second light, a third laser diode that emits a third light, a first submount on which the first laser diode is mounted, a second submount on which the second laser diode is mounted, a third submount on which the third laser diode is mounted, a base submount having a first surface to which the first submount, the second submount, and the third submount are attached, a first filter that transmits the first light and reflects the second light to combine the first light and the second light, a second filter that transmits the first combined light combined by the first filter and reflects the third light to combine the first combined light and the third light, an emission window that transmits the second combined light combined by the second filter, and a cap that is attached so as to cover the first laser diode, the second laser diode, the third laser diode, the first submount, the second submount, the third submount, the first filter, the second filter, and the base submount. When the second combined light is converted into collimated light by a lens provided outside the cap, the ellipticity of the second combined light is 0.9 or more.

[0010] The inventors have intensively studied measures for miniaturization and compactification of the device configuration of an optical module that combines and emits light emitted from a plurality of laser diodes. Then, they considered omitting a plurality of lenses that convert the light emitted from each laser diode into collimated light. Since the light emitted from the laser diode is divergent light, when the light is directly combined by the filter without being converted into collimated light, if the accuracy of the fixed position of each laser diode is low, the optical path difference becomes large. As a result, it has been found that the ellipticity of the emitted light (beam) becomes high, the beam deviates from a perfect circular shape, or the beam diameter becomes large.

[0011] According to the optical module of the present disclosure, when the second combined light is converted into collimated light by a lens provided outside the cap, the ellipticity of the second combined light is 0.9 or more. Therefore, it becomes easy to make the ellipticity of the beam approach 1, and it is possible to control the beam diameter so that it does not become too large. In this case, since the optical module does not include a plurality of lenses for adjusting the spot size of the light emitted from each laser diode in the cap, the number of components constituting the optical module can be reduced. As described above, according to the above optical module, it is possible to easily obtain a desired beam shape while achieving miniaturization and compactness of the device configuration.

[0012] (2) In the above (1), the beam diameter of the second combined light may be 0.4 mm or more and 1.6 mm or less. Since such an optical module has a relatively small beam diameter of the second combined light, it is suitably used, for example, as a laser beam scanner for improving video quality.

[0013] (3) In the above (1) or (2), at least one of the thickness of the first filter and the thickness of the second filter may be 5 μm or more and 50 μm or less. According to such a configuration, while making the ellipticity of the second combined light close to 1, the beam diameter can be made relatively small. Therefore, it becomes easier to obtain a more desired beam shape.

[0014] (4) In any of the above (1) to (3), the optical module may further include a block portion to which the base submount is attached, and a base portion to which the block portion and the cap are attached. By doing so, the height of the beam emission can be easily adjusted by attaching the block portion. In addition, optical components such as the first laser diode can be protected from the outside by the base portion and the cap, and the handling property can be improved.

[0015] (5) In any of (1) to (4) above, the first surface may be provided with a protrusion that rises at the position where at least one of the first submount, second submount, third submount, first filter, and second filter is fixed. By doing so, the risk of the bonding material that joins with the protrusion flowing out of the protrusion due to surface tension when it melts can be reduced. Therefore, the spreading of molten bonding material from the position where the protrusion is provided can be reduced, and each member can be fixed with high precision. As a result, a more desired beam shape can be obtained.

[0016] (6) In (5) above, the protrusion may include a first protrusion to which the first filter is fixed and a second protrusion to which the second filter is fixed. The area of ​​the first protrusion may be larger than the area of ​​the second protrusion. By doing so, it becomes easier to miniaturize the optical module while preventing liquid leakage when the bonding material is melted.

[0017] (7) In any of (1) to (6) above, the second multiplexed light emitted from the emission window may be divergent light. Such an optical module does not contain a lens inside the cap, making it easier to make compact and manufacture.

[0018] [Details of the embodiments of this disclosure] Embodiments of the optical module of this disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0019] (Embodiment 1) The optical module in Embodiment 1 will now be described. Figures 1 and 2 are external perspective views of the optical module according to Embodiment 1, respectively. In Figure 1, the cap, which will be described later, is shown with a dashed line, and in Figure 2, the state with the cap removed is shown. Figure 3 is a schematic plan view showing the structure of the optical module shown in Figure 2. Figure 3 is a view in the direction of arrow III in Figure 2. Figure 4 is a schematic front view of the optical module shown in Figure 2. Figure 4 is a view in the direction of arrow IV in Figure 2. Figure 5 is a schematic side view of the optical module shown in Figure 2. Figure 5 is a view in the direction of arrow V in Figure 2.

[0020] Referring to Figures 1, 2, 3, 4, and 5, the optical module 10A includes a cap 12A, a base submount 14A, a first submount 31A, a second submount 32A, a third submount 33A, a first laser diode 41A, a second laser diode 42A, a third laser diode 43A, a first filter 51A, and a second filter 52A. The optical module 10A may further include a base portion 11A and a block portion 13A. The base portion 11A and the block portion 13A may be provided separately or as a single unit. In the drawings shown in Figure 1 and subsequent figures, the thickness direction of the base portion 11A is defined as the Z direction, the direction perpendicular to the Z direction in which the second laser diode 42A and the third laser diode 43A are aligned is defined as the Y direction, and the directions perpendicular to the Z direction and the Y direction are defined as the X direction. The optical module 10A emits light in the direction indicated by arrow F in Figure 1. AuSn solder is placed on both the front and back surfaces of the first submount 31A, the second submount 32A, and the third submount 33A.

[0021] The base portion 11A is flat. The base portion 11A is rectangular in shape, with chamfered edges at all four corners so that they are rounded when viewed in the thickness direction (Z direction). Specifically, the base portion 11A is longer in the Y direction than in the X direction. The base portion 11A includes a first main surface 15A and a second main surface 16A, which is separate from the first main surface 15A. The first main surface 15A and the second main surface 16A are each surfaces perpendicular to the Z direction, i.e., surfaces parallel to the XY plane. Various components included in the optical module 10A, specifically the base submount 14A and the first submount 31A, are mounted on the first main surface 15A. Multiple lead pins 17A that penetrate the base portion 11A in the thickness direction are attached to the base portion 11A at intervals in the X and Y directions, respectively. Multiple lead pins 17A are wired to the first laser diode 41A, etc., and are used to supply power and control signals during the operation of the optical module 10A.

[0022] The cap 12A is a lid welded to the base portion 11A. The cap 12A is positioned in contact with the first main surface 15A. The cap 12A is provided with a light-transmitting emission window 18A. Components positioned on the base portion 11A are surrounded and sealed by the base portion 11A and the cap 12A. That is, the base portion 11A and the cap 12A as a protective container surround the block portion 13A, base submount 14A, first submount 31A, second submount 32A, third submount 33A, first laser diode 41A, second laser diode 42A, third laser diode 43A, first filter 51A, and second filter 52A. The first laser diode 41A, second laser diode 42A, third laser diode 43A, first filter 51A, and second filter 52A positioned on the base portion 11A are hermetically sealed by the cap 12A. The ejection window 18A is provided on one of the wall surfaces that make up the cap 12A, specifically on the wall surface of the cap 12A that is parallel to the XZ plane.

[0023] The block portion 13A is rectangular in shape. The block portion 13A is placed on the first main surface 15A of the base portion 11A. When viewed in the Z direction, the length of the block portion 13A in the Y direction is longer than the length in the X direction. The block portion 13A is used, for example, to adjust the height of the emitted light (length in the Z direction), as will be described later. The block portion 13A may also be used as a heat sink. For example, AlN (aluminum nitride) is used as the material for the block portion 13A.

[0024] The base submount 14A is flat and rectangular in shape, with a length in the Y direction being longer than the length in the X direction when viewed in the Z direction. The thickness of the base submount 14A, i.e., its length in the Z direction, is shorter than the thickness of the block portion 13A, i.e., its length in the Z direction. In this embodiment, the thickness of the base submount 14A is 0.15 mm, and the thickness of the block portion 13A is 0.9 mm. The base submount 14A includes a first surface 21A and a second surface 22A, which is different from the first surface 21A. The first surface 21A and the second surface 22A are each surfaces perpendicular to the Z direction, i.e., surfaces parallel to the XY plane. For example, AlN (aluminum nitride) is used as the material for the base submount 14A. The flatness of the first surface 21A is 5 μm or less. The base submount 14A is fixed to the block portion 13A such that the second surface 22A faces the block portion 13A. A bonding material such as solder is used to fix the base submount 14A and the block portion 13A. The first submount 31A, the second submount 32A, the third submount 33A, the first filter 51A, and the second filter 52A are fixed onto the first surface 21A of the base submount 14A.

[0025] Figure 6 is an exploded perspective view of the optical module 10A shown in Figure 2. Figure 7 is a schematic perspective view showing the base submount 14A, first submount 31A, second submount 32A, third submount 33A, first laser diode 41A, second laser diode 42A, and third laser diode 43A included in the optical module 10A shown in Figure 2, before they are fixed in place.

[0026] Referring together to Figures 6 and 7, the first surface 21A of the base submount 14A may be provided with a plurality of protrusions 23A, 24A, a first protrusion 25A, and a second protrusion 26A. Each of the protrusions 23A, 24A, 25A, and 26A is formed such that a part of the first surface 21A is raised. Each of the protrusions 23A, 24A, 25A, and 26A is formed by arranging layers of Ti (titanium) 0.1 μm thick, Pt (platinum) 0.2 μm thick, and Au (gold) 0.5 μm thick in order from the bottom layer. A UV-curing resin is further arranged on top of the protrusions 25A and 26A so that the height of the top surface is approximately 100 μm. The protrusion 23A is shaped to accommodate the first submount 31A and the second submount 32A. The protrusion 24A is rectangular in shape, with its length in the X direction being longer than its length in the Y direction when viewed in the Z direction, and its shape follows the outer shape of the third submount 33A when viewed in the Z direction. The protrusions 25A and 26A are circular in shape when viewed in the Z direction. The diameter of the protrusion 25A is larger than the diameter of the protrusion 26A. The first submount 31A and the second submount 32A are mounted on the protrusion 23A. The third submount 33A is mounted on the protrusion 24A. The first filter 51A is mounted on the protrusion 25A. The second filter 52A is mounted on the protrusion 26A. In this embodiment, components are mounted on the protrusions 23A, 24A, 25A, and 26A, and the bonding material is melted by heating to join them together. The process for the first filter 51A and the second filter 52A is carried out by laser heating the resin provided on the first protrusion 25A and the second protrusion 26A. In this way, the first submount 31A, the second submount 32A, the third submount 33A, the first filter 51A, and the second filter 52A are fixed on the first surface 21A of the base submount 14A.

[0027] Markings 27A and 28A may be provided on the first surface 21A of the base submount 14A. In this embodiment, two markings 27A and 28A are provided spaced apart when viewed in the Z direction. Markings 27A and 28A are both the same cross shape when viewed in the Z direction. Marking 27A is provided near the protrusion 23A, and marking 28A is provided near the protrusion 25A. These markings 27A and 28A are used as markers when fixing the first submount 31A, etc.

[0028] The first laser diode 41A is mounted on the first submount 31A. The first laser diode 41A emits a first light (e.g., red light L1) in the Y direction (opposite direction to arrow Y). The second laser diode 42A is mounted on the second submount 32A. The second laser diode 42A emits a second light (e.g., green light L2) in the X direction (opposite direction to arrow X). That is, the direction of emission of the red light L1 emitted from the first laser diode 41A and the direction of emission of the green light L2 emitted from the second laser diode 42A intersect perpendicularly. The third laser diode 43A is mounted on the third submount 33A. The third laser diode 43A emits a third light (e.g., blue light L3) in the X direction (opposite direction to arrow X). In other words, the emission direction of the red light L1 emitted from the first laser diode 41A and the emission direction of the blue light L3 emitted from the third laser diode 43A intersect perpendicularly. The red light L1 has a wavelength of approximately 620 nm to 800 nm, the green light L2 has a wavelength of approximately 495 nm to 570 nm, and the blue light L3 has a wavelength of approximately 420 nm to 495 nm.

[0029] The first filter 51A transmits the red light L1 emitted from the first laser diode 41A and reflects the green light L2 emitted from the second laser diode 42A. As a result, the first filter 51A combines the red light L1 and the green light L2 as the first combined light LA. The first combined light LA ​​propagates in the Y direction (opposite direction to arrow Y). The second filter 52A transmits the first combined light LA ​​combined by the first filter 51A and reflects the blue light L3 emitted from the third laser diode 43A. As a result, the second filter 52A combines the first combined light LA ​​and the blue light L3 as the second combined light LB. The second combined light LB propagates in the Y direction (opposite direction to arrow Y). The second combined light LB is emitted to the outside through the emission window 18A provided in the cap 12A. Both the first filter 51A and the second filter 52A are wavelength-selective filters and may be dielectric multilayer filters.

[0030] The thickness T1 of the first filter 51A and the thickness T2 of the second filter 52A shown in Figure 3 may each be between 5 μm and 50 μm. In this embodiment, both the thickness T1 of the first filter 51A and the thickness T2 of the second filter 52A are 30 μm.

[0031] The ellipticity of the second combined light LB, which is combined by the second filter 52A, is 0.9 or greater when the second combined light LB is converted into collimated light by the lens provided on the outside of the cap 12A. The ellipticity of the second combined light LB may be 1.1 or less. Note that the ellipticity of the second combined light LB is the value furthest from 1 among the ellipticities of red light, green light, and blue light. When the second combined light LB is emitted from the exit window 18A as diffused light and projected onto a plane 0.5 mm away from the exit window 18A, the beam diameter is 0.4 mm to 1.6 mm. The ellipticity is measured using a beam analyzer (CMOS-1.001-Nano manufactured by CINOGY Technologies), where ellipticity = (beam intensity 1 / e 2 (length in the Y direction) / (beam intensity 1 / e 2 It was calculated from the length in the X direction.

[0032] An example of a manufacturing method for the optical module 10A will be described. Figure 8 is a flowchart showing a typical process in the manufacturing method of the optical module 10A in Embodiment 1. Referring to Figure 8, first, as a first fixing step, the first submount 31A is placed on the first surface 21A of the base submount 14A based on the positions of markings 27A and 28A provided on the first surface 21A, and then the first laser diode 41A that emits the first light is placed on the first submount 31A based on the positions of markings 27A and 28A. The first submount 31A and the first laser diode 41A, and the first submount 31A and the base submount 14A are fixed simultaneously by heating. The first light is, for example, red light L1. Specifically, the first submount 31A is fixed on the protrusion 23A and the first laser diode 41A is fixed on the first submount 31A such that the direction in which the red light L1 is emitted from the first laser diode 41A is opposite to the direction of arrow Y. For fixing, for example, AuSn solder provided on both sides of the first submount 31A is used. The same applies to the second submount 32A, the second laser diode 42A, the third submount 33A, and the third laser diode 43A.

[0033] After the first fixing step, as a second fixing step, the second submount 32A is positioned on the first surface 21A based on the positions of markings 27A and 28A, and further, the second laser diode 42A that emits second light is positioned on the second submount 32A based on at least two positions of markings 27A and 28A and the position of the first laser diode 41A. The second light is, for example, green light L2. By heating, the second submount 32A and the second laser diode 42A, and the second submount 32A and the base submount 14A are fixed simultaneously (S12). Specifically, the second submount 32A is fixed on the protrusion 23A and the second laser diode 42A is fixed on the second submount 32A such that the direction in which the green light L2 is emitted from the second laser diode 42A is opposite to the direction of arrow X. In this case, the mounting positions of the already fixed first submount 31A and first laser diode 41A are recognized by image recognition using markings 27A and 28A, and based on the results, the positioning of the second submount 32A and second laser diode 42A is precisely adjusted to fix the second submount 32A and second laser diode 42A.

[0034] After the second fixing step, as a third fixing step, the third submount 33A is positioned on the first surface 21A based on the positions of markings 27A and 28A, and further, the third laser diode 43A that emits the third light is positioned on the third submount 33A based on at least two of the positions of markings 27A and 28A, the position of the first laser diode 41A, and the position of the second laser diode 42A. The third light is, for example, blue light L3. By heating, the third submount 33A and the third laser diode 43A, and the third submount 33A and the base submount 14A are fixed simultaneously (S13). Specifically, the third submount 33A is fixed on the protrusion 24A and the third laser diode 43A is fixed on the third submount 33A such that the direction in which the blue light L3 is emitted from the third laser diode 43A is opposite to the direction of arrow X. In this case, the mounting positions of the already fixed first submount 31A, first laser diode 41A, second submount 32A, and second laser diode 42A are recognized by image recognition using markings 27A and 28A, and based on the results, the third submount 33A and third laser diode 43A are positioned with high precision and fixed in place.

[0035] After the third fixing step, the base part fixing step is performed by placing the base submount 14A and the block part 13A on the base part 11A. The base submount 14A and the block part 13A, and the block part 13A and the base part 11A are fixed simultaneously by heating (S14). For fixing, for example, AuSn solder provided on the front and back of the block part 13A is used.

[0036] After the base fixing process, the following filter fixing process is performed. That is, the base fixing process is performed before the filter fixing process. A first filter 51A that transmits the first light, red light L1, and reflects the second light, green light L2, thereby combining the red light L1 and the green light L2, and a second filter 52A that transmits the first combined light LA ​​combined by the first filter 51A and reflects the third light, blue light L3, thereby combining the first combined light LA ​​and the blue light L3, are fixed to the first surface 21A (S15). The position of the first filter 51A during fixing is adjusted based on the positions of at least two of the markings 27A, 28A, the first laser diode 41A, and the second laser diode 42A. The position of the second filter 52A during fixing is adjusted based on the positions of at least two of the following: marking 27A, marking 28A, first laser diode 41A, second laser diode 42A, third laser diode 43A, and first filter 51A. In this embodiment, the first filter 51A is fixed on the protrusion 25A, and the second filter 52A is fixed on the protrusion 26A. When fixing the first filter 51A, it is tilted 45 degrees in both the X and Y directions, respectively, so that the direction in which the first combined light LA, obtained by combining the red light L1 and the green light L2, propagates is opposite to the direction of arrow Y. Furthermore, when fixing the second filter 52A, it is tilted 45 degrees in both the X and Y directions, and fixed on the convex portion 26A such that the direction in which the second combined light LB, obtained by combining the first combined light LA ​​and the blue light L3, propagates is opposite to the direction of arrow Y.

[0037] After the filter fixing step, the cap 12A is fixed to the base portion 11A in a cap fixing step (S16). In this embodiment, the cap 12A is provided with an emission window 18A that transmits the second combined light LB, which is combined by the second filter 52A, and the cap 12A is fixed on the first main surface 15A of the base portion 11A so that the second combined light LB passes through the emission window 18A. In this case, the cap 12A is fixed to the base portion 11A by hermetically sealing the cap 12A to the first main surface 15A of the base portion 11A so as to cover the first laser diode 41A, the second laser diode 42A, the third laser diode 43A, the first submount 31A, the second submount 32A, the third submount 33A, the first filter 51A, the second filter 52A, the base submount 14A, and the block portion 13A. An optical module 10A is obtained by this manufacturing method.

[0038] According to the manufacturing method of the optical module 10A, firstly, in the first fixing step, it is easy to accurately fix the first submount 31A and the first laser diode 41A to the first surface 21A of the base submount 14A based on the positions of markings 27A and 28A. Next, in the second fixing step, the second submount 32A and the second laser diode 42A are positioned and fixed based on the positions of markings 27A and 28A and the position of the first laser diode 41A. This makes it easy to fine-tune the fixing position of the second submount 32A and the second laser diode 42A so that the green light L2 is appropriately combined according to the position of the red light L1. Therefore, the position of the green light L2 can be aligned with the position of the red light L1 with high precision. Next, in the third fixing step, the third submount 33A and the third laser diode 43A are positioned and fixed based on at least two of the positions of markings 27A and 28A, the position of the first laser diode 41A, and the position of the second laser diode 42A. This makes it easier to fine-tune the fixing position of the third submount 33A and the third laser diode 43A so that the blue light L3 is appropriately combined with the first combined light LA ​​of the red light L1 and the green light L2. Therefore, the position of the blue light L3 can be aligned with the position of the first combined light LA ​​of the red light L1 and the green light L2 with high precision. After the base fixing step, the first filter 51A and the second filter 52A are fixed in the filter fixing step, so that the first filter 51A and the second filter 52A can be fixed with high precision with respect to the position of each light. In this way, the second combined light LB, obtained by precisely combining red light L1, green light L2, and blue light L3, makes it easier to bring the beam ellipticity closer to 1 when collimated using a lens, and the beam diameter can be controlled so that it does not become too large. The optical module 10A manufactured in this way does not contain multiple lenses that convert the light emitted from each laser diode into collimated light within the cap 12A, making it easy to reduce weight, miniaturize, and make the device configuration more compact.As described above, the manufacturing method for the optical module 10A makes it easy to obtain a desired beam shape while miniaturizing the device and making the device configuration more compact. Note that the arrangement of the first laser diode 41A, the second laser diode 42A, and the third laser diode 43A is not limited to the configuration shown in Figure 1. For example, the third laser diode 43A may be placed in the position of the first laser diode 41A in Figure 1, the first laser diode 41A may be placed in the position of the second laser diode 42A, and the first laser diode 41A may be placed in the position of the third laser diode 43A. Also, although it has been stated that the first laser diode 41A emits red light, the second laser diode 42A emits green light, and the third laser diode 43A emits blue light, this is not limited to this. For example, the first laser diode 41A may emit green light. In short, by placing and fixing the second submount 32A and the second laser diode 42A, which are to be placed next, based on the position of the first laser diode 41A which is placed first, fine adjustments can be easily made.

[0039] The first surface 21A may be provided with protrusions 23A, 24A, 25A, and 26A that rise at the positions where the first submount 31A, second submount 32A, third submount 33A, first filter 51A, and second filter 52A are fixed. The bonding material for the first fixing step, second fixing step, and third fixing step is, for example, AuSn solder provided on the front and back surfaces of the first submount 31A, second submount 32A, and third submount 33A. This bonding material fixes the first submount 31A to the first laser diode 41A, and the first submount 31A to the protrusions 23A. This bonding material also fixes the second submount 32A to the second laser diode 42A, and the second submount 32A to the protrusions 23A. Furthermore, this bonding material fixes the third submount 33A to the third laser diode 43A, and the third submount 33A to the protrusion 24A. The bonding material in the filter fixing process is a UV-curing resin placed on the protrusions 25A and 26A. When the bonding material that joins the protrusions 23A, 24A, 25A, and 26A melts, the risk of it flowing out of the protrusions 23A, 24A, 25A, and 26A due to surface tension can be reduced. Therefore, the spreading of the molten bonding material from the positions where the protrusions 23A, 24A, 25A, and 26A are provided can be reduced, and each component can be fixed with high precision.

[0040] The manufacturing method for the optical module 10A may include a base fixing step, in which the base submount 14A is fixed to the block section 13A and the block section 13A is fixed to the base section 11A, before the filter fixing step. The cap fixing step involves fixing the cap 12A to the base section 11A so as to cover the first laser diode 41A, the second laser diode 42A, the third laser diode 43A, the first submount 31A, the second submount 32A, the third submount 33A, the first filter 51A, the second filter 52A, the base submount 14A, and the block section 13A. Therefore, during the manufacturing of the optical module 10A, the beam emission height can be easily adjusted by fixing the block section 13A. In addition, by fixing the cap 12A to the base section 11A, optical components such as the first laser diode 41A can be protected from the outside, and an optical module 10A with improved handling can be manufactured.

[0041] The optical module 10A includes a first laser diode 41A that emits a first light, a second laser diode 42A that emits a second light, a third laser diode 43A that emits a third light, a first submount 31A on which the first laser diode 41A is mounted, a second submount 32A on which the second laser diode 42A is mounted, a third submount 33A on which the third laser diode 43A is mounted, a base submount 14A having a first surface 21A on which the first submount 31A, the second submount 32A and the third submount 33A are attached, and a device that transmits the first light and reflects the second light, thereby transmitting the first light and the second light. The device comprises a first filter 51A that combines the light from two sources, a second filter 52A that transmits the first combined light LA ​​combined by the first filter 51A and reflects the third light to combine the first combined light LA ​​and the third light, and a cap 12A that is attached to cover the first laser diode 41A, the second laser diode 42A, the third laser diode 43A, the first submount 31A, the second submount 32A, the third submount 33A, the first filter 51A, the second filter 52A, and the base submount 14A. When the second combined light is converted into collimated light by a lens provided on the outside of the cap 12A, the ellipticity of the second combined light LB is 0.9 or greater.

[0042] According to the optical module 10A, when the second multiplexed light LB is converted into collimated light by the lens provided on the outside of the cap 12A, the ellipticity of the second multiplexed light LB is 0.9 or greater. Therefore, it becomes easier to bring the beam ellipticity closer to 1, and the beam diameter can be controlled so that it does not become too large. In this case, the optical module 10A does not include multiple lenses within the cap 12A that adjust the spot size of the light emitted from each laser diode, thus reducing the number of components that make up the optical module 10A. As described above, the optical module 10A makes it easy to obtain a desired beam shape while achieving miniaturization and a compact device configuration.

[0043] The beam diameter of the second combined light LB may be between 0.4 mm and 1.6 mm. Such an optical module 10A is suitable for use as a laser beam scanner, for example, to improve image quality, because the beam diameter of the second combined light LB is relatively small.

[0044] The thickness T1 of the first filter 51A and the thickness T2 of the second filter 52A may both be between 5 μm and 50 μm. This allows for a relatively small beam diameter while keeping the ellipticity of the second combined wave light close to 1. Therefore, it becomes easier to obtain a more desired beam shape.

[0045] The first surface 21A may be provided with protrusions 23A, 24A, 25A, and 26A that rise at the positions where the first submount 31A, second submount 32A, third submount 33A, first filter 51A, and second filter 52A are fixed. When the bonding material that joins with the protrusions 23A, 24A, 25A, and 26A melts, the risk of it flowing out of the protrusions 23A, 24A, 25A, and 26A due to surface tension can be reduced. Therefore, the spreading of molten bonding material from the positions where the protrusions 23A, 24A, 25A, and 26A are provided can be reduced, and each member can be fixed with high precision. As a result, a more desired beam shape can be obtained.

[0046] The protrusions 23A, 24A, 25A, and 26A may include a first protrusion 25A to which the first filter 51A is fixed, and a second protrusion 26A to which the second filter 52A is fixed. The area of ​​the first protrusion 25A may be larger than the area of ​​the second protrusion 26A. This makes it easier to miniaturize the optical module 10A while preventing liquid leakage during the melting of the bonding material.

[0047] The optical module 10A may include a block section 13A to which a base submount 14A is attached, and a base section 11A to which the block section 13A and a cap 12A are attached. The height of the beam emission can be easily adjusted by attaching the block section 13A. In addition, the base section 11A and cap 12A can protect optical components such as the first laser diode 41A from the outside, thereby improving handling.

[0048] The second multiplexed light LB emitted from the emission window 18A may be divergent light. Since such an optical module 10A does not include a lens inside the cap 12A, it is easier to make it compact and easier to manufacture.

[0049] (modified version) The optical module may be used in conjunction with a lens. Figure 9 is an external perspective view of optical module 10B used in conjunction with a lens.

[0050] Referring to Figure 9, the optical module 10B includes a lens 53B on the outside of the cap 12A that converts the spot size of the second combined light LB combined by the second filter 52A. The lens 53B is fixed to the cap 12A, for example, on the outside of the exit window 18A. The second combined light LB that has passed through the exit window 18A is incident on the lens 53B. In this embodiment, the lens 53B converts the spot size of the second combined light LB to collimated light. In the manufacturing method of the optical module described above, as a lens fixing step, after the filter fixing step, the lens 53B that converts the spot size of the second combined light LB combined by the second filter 52A is fixed. The lens 53B may be attached to the first main surface 15A, for example, on the outside of the exit window 18A.

[0051] According to the optical module 10B, the attached lens 53B can convert the second multiplexed light LB into collimated light. Therefore, it is possible to manufacture an optical module 10B that can be easily made into a more desired beam shape.

[0052] Figures 10, 11, and 12 are graphs of simulation results showing the relationship between lens position and beam diameter. Figures 10, 11, and 12 show the cases where the thickness of the first and second filters are different. In Figures 10, 11, and 12, the horizontal axis represents the lens position (μm), and the vertical axis represents the beam diameter (μm). In Figures 10, 11, and 12, line 61B shows the length of the red light in the X direction, line 62B shows the length of the red light in the Y direction, line 63B shows the length of the green light in the X direction, line 64B shows the length of the green light in the Y direction, line 65B shows the length of the blue light in the X direction, and line 66B shows the length of the blue light in the Y direction. Figure 10 shows the case where the thickness of the first and second filters is 0 μm. Figure 11 shows the case where the thickness of the first and second filters in Embodiment 1 is 30 μm each. Figure 12 shows the case where the thickness of the first and second filters is 100 μm each. In Figures 10, 11, and 12, the mounting positions of the lenses are indicated by dashed lines parallel to the vertical axis. The lens positions are adjusted so that the ellipticity of each color approaches 1 and the beam diameter of each color is small. Figure 13 is a table showing the relationship between beam diameter and ellipticity in Figures 10, 11, and 12. The beam diameter in Figure 13 is the maximum value of the length in the X direction and the length in the Y direction of the light of each color.

[0053] Referring to Figures 10, 11, 12, and 13, as shown in Figure 10, if the thickness of the first and second filters is set to 0 μm, even if the lens position is set to 5 μm and placed in the optimal position, the ellipticity of the second combined light LB will be less than 0.9, which is farther than 1 (where the length in the X direction and the length in the Y direction are equal). Also, as shown in Figure 12, if the thickness of the first and second filters is set to 100 μm each, even if the lens position is set to the optimal position, for example, the beam diameter of red light will be larger than 120 μm, resulting in a large beam diameter. In contrast, as shown in Figure 11, if the thickness of the first and second filters is set to 30 μm each, and the lens position is set to the optimal position, the ellipticity of the second combined light LB can be made 0.9 or greater, i.e., close to 1, and the beam diameter of all colors of light when collimated can be made less than 120 μm, thus reducing the beam diameter.

[0054] (Embodiment 2) Embodiment 2, another embodiment, will now be described. Figures 14 and 15 are external perspective views of the optical module according to Embodiment 2, respectively. In Figure 14, the cap is shown with a dashed line, and in Figure 15, the state with the cap removed is shown. Figure 16 is a schematic plan view showing the structure of the optical module shown in Figure 15. Figure 16 is a view in the direction of arrow XVI shown in Figure 15. Figure 17 is a schematic front view of the optical module shown in Figure 15. Figure 17 is a view in the direction of arrow XVII shown in Figure 15. Figure 18 is a schematic side view of the optical module shown in Figure 15. Figure 18 is a view in the direction of arrow XVIII shown in Figure 15. The optical module in Embodiment 2 has basically the same configuration as in Embodiment 1 and produces the same effect. However, the optical module in Embodiment 2 differs from that of Embodiment 1 in that it does not include a block section, etc.

[0055] Referring to Figures 14, 15, 16, 17, and 18, the optical module 10C in Embodiment 2 is a so-called CAN type optical module and includes a cap 12C, a base submount 14A, a first submount 31A, a second submount 32A, a third submount 33A, a first laser diode 41A, a second laser diode 42A, a third laser diode 43A, a first filter 51A, and a second filter 52A. The optical module 10C may further include a base portion 11C and a pedestal portion 13C. The base portion 11C and the pedestal portion 13C may be provided separately or as a single unit. The configuration of the base submount 14A, first submount 31A, second submount 32A, third submount 33A, first laser diode 41A, second laser diode 42A, third laser diode 43A, first filter 51A, and second filter 52A is basically the same as that of the optical module 10A shown in Embodiment 1.

[0056] The base portion 11C is disc-shaped with several notches cut out in the thickness direction (Z direction) in the circumferential direction. Multiple lead pins 17C are provided on the base portion 11C, penetrating in the thickness direction and spaced apart in the X and Z directions. The cap 12C is shaped like a hollow cylindrical member with one side opening closed, and an ejection window 18C is provided in the closed wall portion.

[0057] The base portion 11C has a first main surface 15C and a second main surface 16C separate from the first main surface 15C, and a pedestal portion 13C is provided on the first main surface 15C so as to extend in the Y direction. The first main surface 15C and the second main surface 16C are surfaces perpendicular to the Y direction, i.e., surfaces parallel to the XZ plane. The pedestal portion 13C is provided with a mounting surface 19C parallel to the XY plane. The base submount 14A is fixed on the mounting surface 19C. Figure 19 is a schematic perspective view showing the state in which the base submount 14A is fixed to the pedestal portion 13C of the base portion 11C in the optical module 10C of Embodiment 2. Referring to Figure 19 as well, when fixing the base submount 14A to the pedestal portion 13C, a thin sheet of solder 29C is used as a bonding material to be placed between the mounting surface 19C and the second surface 22A of the base submount 14A. Solder 29C is AuSu solder.

[0058] The optical module 10C makes it easy to obtain a desired beam shape while achieving miniaturization and a compact device configuration.

[0059] (modified version) The optical module may be used with a lens to adjust the spot size of the emitted light. Figure 20 is an external perspective view of the optical module 10D used with a lens.

[0060] Referring to Figure 20, the optical module 10D includes a lens 53D outside the cap 12C that converts the spot size of the second combined light LB combined by the second filter 52A. The lens 53D is fixed to the cap 12C, for example, outside the exit window 18C. The second combined light LB that has passed through the exit window 18C is incident on the lens 53D. In this embodiment, the lens 53D converts the spot size of the second combined light LB to collimated light. In the manufacturing method of the optical module described above, as a lens fixing step, after the filter fixing step, the lens 53D that converts the spot size of the second combined light LB combined by the second filter 52A is fixed.

[0061] According to the optical module 10D, the attached lens 53D can convert the second multiplexed light LB into collimated light. Therefore, it is possible to manufacture an optical module 10D that can be easily made into a more desired beam shape.

[0062] (Other embodiments) In the above embodiment, the optical module is provided with a base, but it is not limited to this and does not need to have a base.

[0063] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. At least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways. The scope of the invention is defined by the claims and not by the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0064] 10A, 10B, 10C, 10D Optical module, 11A, 11C Base section, 12A, 12C Cap, 13A Block section, 13C Base section, 14A Base submount, 15A, 15C First main surface, 16A, 16C Second main surface, 17A, 17C Lead pins, 18A, 18C Emission window, 19C Mounting surface, 21A First surface, 22A Second surface, 23A, 24A Protrusion, 25A Protrusion (First protrusion), 26A Protrusion (Second protrusion), 27A, 28A Marking, 29C Solder, 31A First submount, 32A Second submount, 33A Third submount, 41A First laser diode, 42A Second laser diode, 43A Third laser diode, 51A First filter, 52A; Second filter, 53B, 53D; Lens, 61B, 62B, 63B, 64B, 65B, 66B; Line, L1, L2, L3; Light, LA; First combined light, LB; Second combined light, T1, T2; Thickness.

Claims

1. A first laser diode that emits the first light, A second laser diode that emits a second beam of light, A third laser diode that emits a third beam of light, The first submount on which the first laser diode is mounted, The second submount on which the second laser diode is mounted, The third submount on which the third laser diode is mounted, A base submount having a first surface to which the first submount, the second submount, and the third submount are attached, A first filter that transmits the first light and reflects the second light, thereby combining the first light and the second light, A second filter that transmits the first combined light combined by the first filter and reflects the third light, thereby combining the first combined light and the third light, An emission window is provided through which the second combined light, which is combined by the second filter, is transmitted, and the device comprises the first laser diode, the second laser diode, the third laser diode, the first submount, the second submount, the third submount, the first filter, the second filter, and a cap that is attached to cover the base submount, The cap does not contain a lens for adjusting the spot size of the light from the first laser diode, the second laser diode, and the third laser diode, and the second combined light emitted from the emission window is divergent light. The beam diameter of the second combined wave light projected onto a plane 0.5 mm away from the aforementioned emission window is 0.4 mm or more and 1.6 mm or less. When the second multiplexed light is converted into collimated light by the lens provided on the outside of the cap, the ellipticity of the second multiplexed light is 0.9 or more and 1.1 or less, and the beam diameter of each color of light in the collimated light is less than 120 μm. An optical module in which the thickness of both the first filter and the second filter is 5 μm or more and 50 μm or less.

2. The block portion to which the base submount is attached, The optical module according to claim 1, further comprising the block portion and the base portion to which the cap is attached.

3. The optical module according to claim 1 or 2, wherein the first surface is provided with a protrusion that rises at a position where at least one of the first submount, the second submount, the third submount, the first filter, and the second filter is fixed.

4. The aforementioned protrusion is, The first protrusion on which the first filter is fixed, The second filter includes a second protrusion to which the second filter is fixed, The optical module according to claim 3, wherein the area of ​​the first protrusion is larger than the area of ​​the second protrusion.

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