JP2022160196A - Synthetic light generation device - Google Patents

Abstract

To provide a synthetic light generation device that achieves miniaturization, high production efficiency, and reduced manufacturing costs.SOLUTION: A synthetic light generation device includes a base substrate, an optical multiplexer substrate disposed on the base substrate, and a plurality of laser diodes arranged on the base substrate, and since an input port of the optical multiplexer substrate and the emission center of the laser diode are aligned, and the adjustment work of an optical axis and the like is not required, and the overall efficiency of production is improved by separately manufacturing the two substrates, such that the manufacturing cost can be reduced.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present invention relates to a combined light generating device in which a plurality of laser diodes as light sources are mounted on a base substrate and an optical multiplexer substrate is arranged. More specifically, the plurality of laser diodes are mounted on a base substrate having a pedestal for mounting the plurality of laser diodes and a concave structure for fitting and arranging the optical multiplexer substrate. The present invention relates to a combined light generating device in which an optical multiplexer substrate is fitted and arranged.

2. Description of the Related Art In recent years, an optical multiplexer using a plurality of laser diodes as a light source is known in a combined light generation device used as a light source for an image projection device such as a glasses-type terminal or a portable projector (see Patent Document 1). The optical multiplexer is formed by stacking silicon oxide films with a low refractive index and a high refractive index on a silicon substrate using a known chemical vapor deposition method (CVD), sputtering method, or the like, and then photolithography using a photomask. It is manufactured through the steps of patterning by lithography and laminating a low refractive index silicon oxide film.

Also known is a device in which an optical waveguide portion formed on a part of a silicon substrate and a laser diode optically coupled to the end surface of the optical waveguide portion are mounted on the substrate (see Patent Document 2). reference). Here, since the device includes a step of forming the optical waveguide portion and a step of forming the mounting portion of the laser diode, it has a large number of manufacturing steps.

When the optical multiplexer is adopted in the optical waveguide portion of the device and a combined light generating device is manufactured by mounting laser diodes of three colors on the substrate of the device, the combined light generating device becomes larger. Along with this, the number of manufacturing processes is further increased, resulting in an increase in manufacturing cost.

JP 2013-195603 A JP 2009-086238 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synthetic light generating apparatus that achieves miniaturization, high production efficiency, and reduced manufacturing costs.

a base substrate; an optical multiplexer substrate disposed on the base substrate and having a plurality of input ports and at least one output port; and a plurality of light sources disposed on the base substrate; Each of the plurality of light sources is composed of a laser diode and arranged to face each of the plurality of input ports of the optical multiplexer substrate, and the laser diode is provided with an electrode. A light generating device,
The base substrate has a recessed structure for fitting and disposing the optical multiplexer substrate and a pedestal for mounting the laser diode, and the optical multiplexer substrate is fitted into the recessed structure. and the laser diode is mounted in contact with the upper surface of the pedestal,
The concave structure and the pedestal set the light emission center of each of the plurality of laser diodes to a height corresponding to the center of the input port of the optical multiplexer substrate mounted facing each laser diode. Provided is a synthetic light generation device characterized by:

Preferably, the plurality of light sources include at least blue, green and red light sources and are used as light sources of an image projection device.

Preferably, the laser diodes each have a submount.

It is preferable that each of the pedestals is composed of a plurality of pedestal pieces that are divided into at least two pieces, and that a groove parallel to the light emitting direction of the laser diode is provided between the plurality of pedestal pieces.

According to the present invention, by separately manufacturing the base substrate and the optical multiplexer substrate in the combined light generating device, a large number of manufacturing processes can be divided into two manufacturing processes for each of the two substrates. Even if a defective product appears during manufacturing, it does not affect the efficiency of production of the other substrate, and the overall efficiency of production is improved, so that the production cost can be reduced. In addition, since there is no need for adjustment work to match the light emission center of each laser diode with the center of each input port of the optical multiplexer substrate, miniaturization is achieved and production efficiency is high. The present invention relates to a synthetic light generating device that reduces costs.
Here, the emission center of the laser diode means the center of the laser light emission region (NFP/near-field pattern) on one end face of the laser diode.

4 is a diagram of a base substrate in the synthetic light generating device of Example 1. FIG. Here, (a) is a perspective view, (b) is a top view, (c) is a side view seen from the front left direction of the perspective view, and (d) is a front view seen from the front right direction of the perspective view. is. 4 is a diagram of an optical multiplexer substrate in the combined light generation device of Example 1. FIG. Here, (a) is a perspective view, (b) is a top view, (c) is a side view seen from the front left side of the perspective view, and (d) is a front view seen from the output port side of the perspective view. is. FIG. 4A is a side view of the laser diode side of the base substrate in the combined light generating device of Example 1, and an enlarged side view of a concave portion of the base substrate and one input port in the optical multiplexer substrate; FIG. 10A is a side view of the laser diode side of the base substrate in the combined light generation device of Example 2, and an enlarged side view of a concave portion of the base substrate and one input port in the optical multiplexer substrate; 1 is a perspective view of a combined light generating device of Example 1, in which an upside-down optical multiplexer board is fitted and disposed in a concave portion of a base board, and laser diodes of three types of light are mounted on a pedestal. FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the present invention is not limited to these examples.

FIG. 1(a) is a perspective view of a base substrate 100 in the synthetic light generating device of Example 1. Using a silicon substrate 1, a groove for mounting a laser diode is formed by a known method such as dicing or etching. The pedestal portion is divided into four parts by processing with , and the polycrystalline silicon layer 3 and the silicon oxide layer 4 are laminated by a known chemical vapor deposition method or the like, and a known etching process is performed at an appropriate stage. Thus, a base substrate 100 having a pedestal 2 for mounting three laser diodes, an optical multiplexer substrate mounting surface 5, and a recess 6 for disposing the optical multiplexer substrate can be obtained.

FIG. 1(b) is a top view of the base substrate 100, and an optical multiplexer substrate 200 is fitted in the optical multiplexer substrate mounting surface 5 and the recess 6. As shown in FIG. Here, in order to improve fitability, it is preferable to provide a step such that the inner side wall of the recess 6 becomes narrower toward the bottom. Also, three types of laser diodes are mounted in contact with each other so as to traverse three grooves machined between the four pedestals 2 . Here, fitting includes not only the case where the base substrate 100 and the optical multiplexer substrate 200 are tightly fitted with no gap, but also the case where the base substrate 100 and the optical multiplexer substrate 200 are loosely fitted with a certain margin. In the latter case, it is possible to use known bonding/mounting techniques such as using alignment marks.

FIG. 1(c) is a side view of FIG. 1(a) viewed from the left front direction. It becomes the reference plane for mounting.
Here, for the silicon oxide layer 4, other materials such as silicon nitride and titanium oxide can be used instead of silicon oxide. Compared to other materials, silicon oxide has a lower thermal conductivity and is inferior in heat dissipation. Therefore, when silicon oxide is used, it is preferably a thin layer with a thickness of 5 μm or less, and a thickness of 1 μm or less. A thin layer is more preferred.

FIG. 1(d) is a side view of the laser diode mounting portion of the base substrate 100 seen from the right front direction of FIG. For example, blue, green, and red laser diodes are mounted from the left so as to traverse the . Here, the laser diode has a submount and is mounted downwardly. The polycrystalline silicon layer 3 serves as a reference plane for mounting the laser diode, the two pedestals 2 on the left side have the same reference plane height, and the rightmost pedestal 2 has a slightly higher reference plane height.

FIG. 2(a) is a perspective view of an optical multiplexer substrate 200 in the synthetic light generating apparatus of Example 1. An undercladding layer 8 is formed on a silicon substrate 7 by a known chemical vapor deposition method, etching processing, or the like. , the optical waveguide 9, the over-cladding layer 10, and the optical multiplexer substrate 200 having the optical multiplexer 11 can be obtained.

FIG. 2(b) is a top view of the optical multiplexer substrate 200. For example, three types of light of blue, green and red are input from the input port, pass through the respective optical waveguides 9, and pass through the optical multiplexer. After being multiplexed at 11, the light passes through the optical waveguide 9 and is output from one output port. Here, the shape of the over-cladding layer 10 is formed so that it can be fitted in the concave portion 6 of the base substrate 100 . When the inner sidewall of the recess 6 has a step that narrows downward, the outer sidewall of the over-cladding layer 10 has a step that narrows upward to correspond to the step.

FIG. 2(c) is a side view of FIG. 2(a) seen from the left front direction, the optical waveguide 9 is formed on the undercladding layer 8, and the periphery thereof is covered with the overcladding layer 10. The upper surface of the under clad layer 8 serves as a reference surface for fitting with the base substrate 100 .

FIG. 2(d) is a side view of the output port side of the optical multiplexer substrate 200, and the height of the optical center 13 of the optical waveguide 9 is located at a distance 12 above the upper surface of the undercladding layer 8. .

FIG. 3 is a side view of the laser diode side of the base substrate 100 in the combined light generation device of Example 1, and an enlarged side view of one input port in the recess 6 of the base substrate 100 and the optical multiplexer substrate 200, For example, from the left, blue, green and red laser diodes each have a submount 17, and each laser diode emission center 14-16 is a reference plane so that it is downwardly convex in the groove between the pedestals 2. It is mounted on the polycrystalline silicon layer 3 in contact therewith. Here, there may be a space 18 between the groove and the laser diode, and a space 19 between the recess 6 and the overcladding layer 10 of the input port.

The submount 17 is made of silicon, silicon carbide (SiC), copper tungsten (CuW), beryllium oxide (BeO), cubic boron nitride (cBN), aluminum nitride, aluminum oxide, etc., and has high thermal conductivity and heat dissipation. It has the action and function of being excellent in the property. When a plurality of laser diodes are used close to each other as in the present invention, each of the laser diodes has a submount 17 because it is effective in efficiently dissipating heat generated by the laser diodes. preferably.

Further, the heights of the pedestals 2 are adjusted so that the heights of the light emission centers 14 to 16 are all the same and match the height of the optical center 13 of the optical waveguide 9 at the input port. manufactured. Here, the green pedestal 2 is made slightly lower and the red pedestal 2 is made slightly higher than the blue pedestal 2 . Furthermore, in the horizontal direction as well, the optical axes of the three colors of light are aligned with the optical centers of the three optical waveguides 9 at the input ports of the optical multiplexer substrate 200, respectively. A step or the like may be provided to facilitate horizontal positioning. Although the electrodes and the metal wires connected to the electrodes are not shown, they can be attached at arbitrary positions.

FIG. 4 is a side view of the laser diode side of the base substrate 100 and an enlarged side view of one input port in the recess 6 of the base substrate 100 and the optical multiplexer substrate 200 in the combined light generating device of the second embodiment. Here, each laser diode does not have a sub-mount 17, and consists only of a laser diode body. As shown, it is mounted in contact with the polycrystalline silicon layer 3 which is the reference plane. Further, unlike the first embodiment, the pedestal 2 may be integral without having grooves, but the heights of the light emitting centers 14 to 16 are all unified to the same height, and the optical waveguide 9 at the input port The height of each pedestal 2 is adjusted and manufactured so as to match the height of the optical center 13 . Here, the green pedestal 2 is made slightly higher and the red pedestal 2 is made slightly lower than the blue pedestal 2 . Furthermore, in the horizontal direction as well, the optical axes of the three colors of light are aligned with the optical centers of the three optical waveguides 9 at the input ports of the optical multiplexer substrate 200, respectively. A step or the like may be provided to facilitate horizontal positioning. It should be noted that the electrodes and the electrodes can be attached at arbitrary positions in the same manner as in FIG.

FIG. 5 shows the synthesized light of Example 1, in which the optical multiplexer substrate 200 which is turned upside down is fitted and arranged in the concave portion 6 of the base substrate 100, and the laser diodes of three types of light are mounted on the pedestal 2. 1 is a perspective view of a generator; FIG. Here, simply by combining the base substrate 100, the optical multiplexer substrate 200, and each laser diode, the input port of the optical multiplexer substrate 200 and the emission centers 14 to 16 of the laser diodes can be aligned. Since such adjustment work is not required, the manufacturing cost can be reduced. Here, at least blue, green and red are used as the emission colors of the laser diode, which is the light source, but monochromatic light in other visible light regions such as orange, yellow and violet may be used as necessary.
When used as a light source for an image display device, the blue emission wavelength of the laser diode is preferably 430 to 495 nm, the green emission wavelength is preferably 495 to 570 nm, and the red emission wavelength is preferable from the viewpoint of widening the color reproduction range. The wavelength is preferably 620-750 nm.
From the viewpoint of improving heat dissipation, solder connection, metal eutectic connection of gold and tin, and the like are preferable as the method of bonding the submount on which the laser diode is mounted and the base substrate 100 .
Also, a collimator lens, a cylinder lens, or a MEMS mirror may be used after the output port, if necessary.

When manufacturing a substrate in which the base substrate 100 and the optical multiplexer substrate 200 are integrated, a vacuum chamber is used when laminating a silicon oxide film or the like by a chemical vapor deposition method or the like, so processing per lot is possible. number is limited. In addition, since high vacuum conditions are required, it is difficult to increase the capacity of the vacuum chamber, so there is a limit to the reduction in manufacturing cost. In addition, a large number of manufacturing processes are required to integrally form the optical multiplexing section and the pedestal, and if a defective product appears during manufacturing, the manufacturing process up to that point will be wasted, which is also a factor of high cost. is.

In the synthetic light generating device of the present invention, the base substrate 100 and the optical multiplexer substrate 200 are manufactured separately, thereby dividing the above multiple manufacturing processes into two manufacturing processes for each of the two substrates. Even if a defective product appears on the way, it does not affect the production efficiency of the other board, and the overall production efficiency is improved, so it is possible to reduce the manufacturing cost.

Since the base substrate 100 does not have an optical multiplexing portion, it is only necessary to form the pedestal 2 on which the polycrystalline silicon layer 3 and the silicon oxide layer 4 are laminated, except for forming the optical multiplexer substrate mounting surface 5 and the recess 6. Therefore, even if a defective product is produced during the manufacturing process, the production efficiency of the optical multiplexer board 200 is not affected, and the optical multiplexer board 200 can be fitted in the concave portion 6 to be disposed. After laminating low refractive index and high refractive index silicon oxide films, patterning is performed by photolithography using a photomask, and a low refractive index silicon oxide film is further laminated to form the optical multiplexing section 11. Therefore, the production efficiency of the base substrate 100 is not affected even if a defective product is produced during the manufacturing process.

Furthermore, since the optical multiplexer substrate 200 is a substrate smaller than the base substrate 100, the above vacuum chamber is used compared to the case of manufacturing a substrate in which the base substrate 100 and the optical multiplexer substrate 200 are integrated. In the case of processing substrates by using a large number of substrates per lot, the manufacturing cost can be reduced.

INDUSTRIAL APPLICABILITY The synthetic light generation device of the present invention can be used as a light source for an image projection device such as a spectacles-type terminal or a portable projector, and can achieve miniaturization, high production efficiency, and a reduction in manufacturing cost. .

100 Base substrate 200 Optical multiplexer substrate 1 Silicon substrate 2 in base substrate Pedestal 3 Polycrystalline silicon layer 4 Silicon oxide layer 5 Optical multiplexer substrate mounting surface 6 Recess 7 Silicon substrate 8 in optical multiplexer substrate 8 Under clad layer 9 Optical waveguide 10 Overcladding layer 11 Optical multiplexing portion 12 Distance 13 from the upper surface of the undercladding layer 8 to the optical center 13 of the optical waveguide 9 Optical center 14 of the optical waveguide 9 Blue light laser diode emission center 15 Green light laser diode emission center 16 Red Light-emitting center 17 of the optical laser diode Submount 18 Space 19 between the groove and the laser diode Space between the recess 6 and the overcladding layer 10

Claims (4)

a base substrate; an optical multiplexer substrate disposed on the base substrate and having a plurality of input ports and at least one output port; and a plurality of light sources disposed on the base substrate; Each of the plurality of light sources is composed of a laser diode and arranged to face each of the plurality of input ports of the optical multiplexer substrate, and the laser diode is provided with an electrode. A light generating device,
The base substrate has a recessed structure for fitting and disposing the optical multiplexer substrate and a pedestal for mounting the laser diode, and the optical multiplexer substrate is fitted into the recessed structure. and the laser diode is mounted in contact with the upper surface of the pedestal,
The concave structure and the pedestal set the light emission center of each of the plurality of laser diodes to a height corresponding to the center of the input port of the optical multiplexer substrate mounted facing each laser diode. A synthetic light generation device characterized by: 2. A combined light generating device according to claim 1, wherein said plurality of light sources includes at least blue, green and red light sources and is used as a light source of an image projection device. 3. The combined light generating device according to claim 1, wherein each of said laser diodes has a submount. Each of the pedestals is composed of a plurality of pedestal pieces that are divided into at least two pieces, and grooves are provided between the plurality of pedestal pieces in a direction parallel to the light emitting direction of the laser diode. 4. The synthetic light generation device according to any one of 3.

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