WO2022172374A1

WO2022172374A1 - Composite light gernation device and manufacturing method therefor

Info

Publication number: WO2022172374A1
Application number: PCT/JP2021/005045
Authority: WO
Inventors: 明姫野; 浩一堀井; 俊夫勝山; 祥治山田; 慧中尾
Original assignee: セーレンＫｓｔ株式会社; 国立大学法人福井大学
Priority date: 2021-02-10
Filing date: 2021-02-10
Publication date: 2022-08-18

Abstract

Provided are: a composite light generation device for which miniaturization is achieved, production efficiency is high, and manufacturing costs are reduced; and a manufacturing method therefor.　Due to a plurality of individual pedestals being formed at a height at which the light-emitting centers of each of a plurality of laser diodes placed thereon respectively align the centers of a plurality of individual input ports of an optical multiplexer, an adjustment operation for aligning centers is not required

Description

Synthetic light generation device and manufacturing method thereof

The present invention relates to a combined light generating device in which a plurality of laser diodes having electrodes are used as light sources, and a power supply circuit fabricated on the same substrate as an optical multiplexer is electrically connected to the electrodes. More specifically, a plurality of laser diodes having electrodes and containing at least red light (R), green light (G) and blue light (B) are used as light sources, and the light emission center of each laser diode is connected to the optical multiplexer. The present invention relates to a synthetic light generating device and a method of manufacturing the same, which can easily align the emission center of a laser diode with the center of an input port of an optical multiplexer without requiring adjustment work for aligning the center of each input port. .

In recent years, in synthetic light generation devices used as light sources for image projection devices such as glasses-type terminals and portable projectors, miniaturized synthetic light generation devices that consist of an optical multiplexer using a plurality of laser diodes as light sources have been known. (See Patent Document 1, for example).
In a combined light generating device in which light output from a laser diode is input from an input port of an optical multiplexer, multiplexed via an optical waveguide, and output from an output port of the optical multiplexer, the combined light is output from the laser diode. As a means and method for guiding the output light to the input port of the optical multiplexer with high efficiency without causing loss, a microlens is placed between the laser diode and the optical multiplexer, and the output from the laser diode. It is known to shape the output light with a microlens and guide it to the input port of an optical multiplexer, or to once guide the light output from a laser diode to an optical fiber and guide it to the input port of the optical multiplexer. (see

Patent Documents

2 and 3, for example).
However, since a microlens or an optical fiber is used between the laser diode and the optical multiplexer, there is a limit to miniaturization of the combined light generating device and the manufacturing cost increases.

Also known is a combined light generating device in which nothing is used between the laser diode and the optical multiplexer and the laser diode and the optical multiplexer are arranged close to each other (see, for example, Patent Document 4).
However, in this case, adjustment work is required to match the center of the light emission of the laser diode with the center of the input port of the optical multiplexer. In order to align the center of light emission with the center of the input port of the optical multiplexer, three-dimensional positioning must be performed. , there is a limit to the reduction in manufacturing cost.

JP 2013-195603 A JP-A-11-346028 JP-A-7-168040 JP-A-2000-012958

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

a substrate, an optical multiplexer disposed on the substrate and having a plurality of input ports and at least one output port, and a plurality of light sources disposed on the substrate; Each of the light sources is composed of a laser diode and arranged to face each of a plurality of input ports of the optical multiplexer, and the laser diode is attached with an electrode in the combined light generating device, ,
Pedestals each made up of at least one pedestal piece are arranged on the substrate corresponding to the arrangement positions of the plurality of laser diodes, and each of the plurality of laser diodes has its lower surface is placed on the pedestal in contact with the upper surface of the pedestal,
The pedestal is set at a height such that the center of light emission of each of the plurality of laser diodes mounted thereon coincides with the center of the input port of the optical multiplexer arranged facing each laser diode. Provided is a synthetic light generation device characterized by:
Note that the laser diode can be replaced with an edge-emitting LED.

A substrate, an optical multiplexer disposed on the substrate and having a plurality of input ports and at least one output port, and a plurality of light sources disposed on the substrate, the plurality of light sources is composed of a laser diode, and is arranged to face each of a plurality of input ports of the optical multiplexer, and the laser diode is provided with an electrode. ,
(1) The substrate has a function as an undercladding layer, or an undercladding layer preparation step of laminating an undercladding layer on the substrate;
(2) a core layer forming step of forming a core layer to be an optical waveguide of the optical multiplexer on the undercladding layer after the undercladding layer preparing step;
(3) After the core layer forming step, an optical waveguide forming step of patterning an optical waveguide in the core layer by photolithography using a photomask having a pattern corresponding to the shape of the optical waveguide;
(4) an overcladding layer laminating step of laminating an overcladding layer covering the optical waveguide and the undercladding layer after the optical waveguide forming step;
(5) after the step of laminating the over-cladding layer, etching the over-cladding layer and the under-cladding layer to form a pedestal consisting of at least one pedestal piece for mounting the plurality of laser diodes; a pedestal forming step, wherein the pedestal is formed so as to be arranged corresponding to the arrangement positions of the plurality of laser diodes, and The emission center of each of the laser diodes is set to a height that matches the center of each of the plurality of input ports of the optical multiplexer,
(6) After the pedestal forming step, an electric circuit forming step of providing an electrode connecting material on the pedestal portion and forming a metal wire in order to supply current to the electrode attached to the laser diode;
(7) a laser diode disposing step of disposing the laser diode on the substrate by bringing the lower surface of the laser diode into contact with the upper surface of the pedestal after the electric circuit forming step;
A method for manufacturing a synthetic light generating device is provided, comprising:

According to the present invention, a plurality of laser diodes having electrodes and containing at least red light (R), green light (G), and blue light (B) are used as light sources, and the light emission centers of the respective laser diodes are used to combine light. By easily aligning the emission center of the laser diode with the center of the input port of the optical multiplexer, miniaturization and production can be achieved. TECHNICAL FIELD The present invention relates to a synthetic light generating device with high efficiency and reduced manufacturing cost, and a manufacturing method thereof.

1 is a perspective view of a synthetic light generating device of the present invention; FIG. 2 is an enlarged view showing a pedestal on which a laser diode is mounted when two pedestal pieces in FIG. 1 are used as one set; FIG. It is a figure which shows the front view (left side) and side view (right side) in each manufacturing process of the synthetic|combination light production|generation apparatus of this invention. Here, (a) is the undercladding layer laminating step, (b) is the core layer forming step, (c) is the optical waveguide forming step, (d) is the overcladding layer laminating step, (e) is the pedestal forming step, ( f) shows an electric circuit formation step. 4 is a diagram showing the height of the pedestal in Example 1. FIG. FIG. 11 is a diagram showing the height of the pedestal in Example 2;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated, referring drawings.
FIG. 1 shows a perspective view of a synthetic light generating device 1 of the present invention. On the left side of the

silicon substrate

2, 3 sets of pedestals 4 each consisting of 4 sets of pedestal pieces are formed. 3(B) is placed. An electrode (not shown) attached to the lower surface of the laser diode 3 is connected to an electrode connecting member 5 to which current is supplied by a metal wire 6 .
An optical multiplexer 8 is formed on the right side of the silicon substrate 2. Inside the optical multiplexer 8, three input ports 9, An optical waveguide 10 for combining three types of light and an output port 11 for outputting the combined light are formed.
By simply placing the laser diode 3 on the pedestal 4, the center of each light emitting portion 7 of the laser diode 3 (referred to as "light emission center") is aligned with the center of each input port 9. , the height and shape of the pedestal 4 are formed. Specifically, since the height and shape of the light emission center of the laser diode 3 differ depending on the product, when the laser diode 3 is placed on the pedestal piece of the base 4, the height of the light emission center of the laser diode 3 is the same as that of the input port. The height of each pedestal piece of the pedestal 4 is formed so as to match the height of the center of the pedestal 9, and when the laser diode 3 is mounted on the pedestal 4, it is aligned with the axis of the emission center of the laser diode 3. Concave portions or convex portions are formed on the upper portions of the base pieces of the base 4 so that the four corners of the lower surface of the laser diode 3 are brought into contact with each other so that the center axis of the input port 9 is aligned. . The concave portion or convex portion may not be formed as required.

Then, simply by placing the laser diodes 3 on the pedestal 4, the light emission centers of the laser diodes 3 easily match the centers of the input ports 9. Therefore, adjustment work for matching the centers is necessary. is unnecessary.

Although only one output port 11 is shown in FIG. 1, there may be two or more output ports 11 if necessary.
FIG. 1 shows the pedestal 4 having four pedestal pieces in one set. The pedestal may be a set of two rectangular parallelepiped pedestal pieces formed by connecting one piece, and a U-shaped shape formed by connecting four of the above-mentioned pedestal pieces to one piece. may be one pedestal.
Furthermore, although the electrodes are attached to the lower surface of the laser diode 3 in FIG. 1, the surface to which the electrodes are attached is not limited to the lower surface. It may be attached in contact with either surface. In that case, since the electrode connecting member 5 and the metal wire 6 are connected to the electrode to supply current, the configuration is slightly different from that shown in FIG.

Here, the fact that each of the plurality of light sources composed of laser diodes is "arranged facing" each of the plurality of input ports of the optical multiplexer means that the output light plane of the light source is the same as that of the optical multiplexer. However, it is not limited to facing the input port surface of the input port, and may be arranged obliquely as necessary.

Further, the fact that the light emission center of the laser diode 3 coincides with the center of the input port 9 does not only mean that the center axis of the light emission center and the center axis of the input port are strictly aligned. At least, the light emitted from the light emitting part 7 of the laser diode 3 is input to the waveguide 10 from the input port 9 of the optical multiplexer 8, and then is transmitted by the waveguide 10. It means that the light is optically multiplexed and output from the output port 11 as a multiplexed light that can be used as a light source for an image projection device.
Normally, if the intensity of output light without axial misalignment is 100%, the intensity of output light with axial misalignment is set to be in the range of 50% or more and less than 100%.
For example, when the intensity of the output light is set to 50% when there is axial misalignment, the active layer (light-emitting layer) of a general laser diode is extremely thin in the height direction. The amount of axial misalignment (axis misalignment tolerance) is about 1/2 wavelength to 2 wavelengths. As for the horizontal direction, since the width of the active layer of the laser diode is wide in the horizontal direction, the axial deviation tolerance tends to be larger than that in the height direction.

FIG. 2(a) is an enlarged view showing the pedestal 4 on which the laser diode is mounted when two pedestal pieces in the pedestal 4 in FIG. 1 are paired. Here, as in FIG. 1, an electrode (not shown) attached to the bottom surface of the laser diode 3 is connected to an electrode connection member 5 (not shown) to which current is supplied by a metal wire 6. Here, as described with reference to FIG. 1, the surface on which the electrodes of the laser diode 3 are attached is not limited to the bottom surface.
1, the height and shape of the pedestal 4 are formed so that the emission center of each laser diode 3 coincides with the center of each input port 9. As shown in FIG.
FIG. 2(b) is an example in which the entrance shape of the waveguide at the input port 9 is expanded into a tapered shape in order to further increase the tolerance for axial misalignment in the horizontal direction. Compared with FIG. 2A, the output light in the case of no axial misalignment is somewhat reduced, but the tolerance for axial misalignment on the input port 9 side is greatly expanded to several times the wavelength. Also, FIG. 2(b) shows an example in which the tapered shape is expanded only in the horizontal direction, but if necessary, the tapered shape may be expanded only in the height direction, and both the horizontal direction and the height direction may be expanded. It may expand in a tapered shape.

FIGS. 3(a) to 3(f) are diagrams showing a front view (left side) and a side view (right side) in the manufacturing method of the synthetic light generating device of the present invention. Explain the process.
(i) FIG. 3A shows an under-cladding layer 12 formed by forming a silicon oxide film having a low refractive index of about 1.46, for example, on a substrate 2 made of silicon by chemical vapor deposition. shows an under-cladding layer preparation step for laminating the . At this time, the substrate 2 having a function as the under clad layer 12 may be used.

(ii) FIG. 3(b) shows that after the undercladding layer preparation step, high refractive index silicon with a refractive index difference of about 0.5 to 1.5% from the undercladding layer is deposited on the undercladding layer 12. A core layer forming step of depositing an oxide film and laminating a core layer 13 forming an optical waveguide of an optical multiplexer is shown.

(iii) FIG. 3C shows that after the core layer forming step, the optical waveguide 10 is patterned on the core layer 13 by photolithography using a photomask having a pattern corresponding to the shape of the optical waveguide 10. 3 shows an optical waveguide forming process for

(iv) FIG. 3(d) shows that after the optical waveguide formation step, a low refractive index silicon oxide film having an absolute refractive index of about 1.46, for example, is formed on the optical waveguide 10 and the undercladding layer 12. 4 shows an over-cladding layer lamination step of laminating the over-cladding layer 14 by laminating.

(v) FIG. 3(e) shows, after the over-cladding layer laminating process, the over-cladding layer 14 on the front side (left front view) or left side (right side view) on the silicon substrate 2, the optical waveguide 10 and the A pedestal forming step is shown in which the pedestal 4 is formed by etching the under-cladding layer 12 to form a pedestal 4 consisting of a set of four pedestal pieces for mounting the plurality of laser diodes 3 thereon. Here, each of the pedestals 4 is formed so as to be arranged corresponding to the arrangement positions of the plurality of laser diodes 3, and each of the pedestals 4 is arranged to correspond to the plurality of laser diodes mounted thereon. The light emission centers of the laser diodes 3 are set at a height that coincides with the centers of the plurality of input ports 9 of the optical multiplexer 8, and the plurality of input ports 9 of the optical multiplexer 8. and the end face of the output port 11 are polished and exposed to the respective faces.
In addition, the etching process may be performed on the substrate 2 under the under clad layer 12 as necessary.

(vi) In FIG. 3(f), in order to supply a current to the electrodes attached to the laser diode 3 after the pedestal forming step, an electrode connection material 5 is provided on the pedestal portion and a metal wire 6 is formed. 4 shows an electric circuit formation process. Here, the electrode connection member 5 may have any shape as long as it has a contact with the electrode attached to the laser diode 3 . Moreover, the metal wire 6 can be formed by a known method such as forming by printing conductive ink using an inkjet printer, forming by using wiring using lead wires, and the like.

(vii) As shown in FIG. 1, after the electric circuit forming step, the laser diode 3 is placed on the substrate by bringing the lower surface of the laser diode 3 into contact with the upper surface of the pedestal 4. placement process.

In the first embodiment, as shown in FIG. 4, the distance from the lower surface of the light emitting part 7 in the main body of the laser diode 3 differs for each color, so that the height of the upper surface of the pedestal 4 differs for each laser diode 3 of each color. ing. Here, the upper surface of the pedestal 4 of the blue laser diode 3 (B) is higher than the upper surface of the pedestal 4 of the red laser diode 3 (R), and the upper surface of the pedestal 4 of the green laser diode 3 (G) is positioned above the red laser diode 3 (G). By forming the diode 3(R) so as to be lower than the upper surface of the pedestal 4, the heights of the light-emitting portions 7 of the three-color laser diodes 3 are unified, and the bodies of the laser diodes 3 are placed on the respective pedestals. The emission centers of the red (R), blue (B), and green (G) laser diodes 3 can all be aligned with the centers of their respective input ports 9 simply by placing them.

In the second embodiment, as shown in FIG. 5, the distance from the lower surface of the light emitting portion 7 in the main body of the laser diode 3 is approximately the same for each color. An example is shown in which the central axis of the light emitting portion 7 of the laser diode 3 and the central axis of the input port 9 are slightly misaligned in the height direction. Here, compared to the height of the light emitting portion 7 of the red laser diode 3 (R), the height of the light emitting portion 7 of the blue laser diode 3 (B) is slightly lower than that of the light emitting portion 7 of the green laser diode 3 (G). is slightly higher, the light emitted from each laser diode 3 is input to the waveguide 10 from the input port 9 of the optical multiplexer 8, and then optically multiplexed by the waveguide 10, Since the output port 11 outputs combined light that can be used as a light source for an image projection device, the emission centers of the red (R), blue (B), and green (G) laser diodes 3 are all coincides with the center of the input port 9 of .

The synthetic light generating device of the present invention achieves miniaturization, high production efficiency, and reduced manufacturing costs, and can be used as a light source for image projection devices such as glasses-type terminals and portable projectors.

1 synthetic light generation device 2 silicon substrate 3 laser diode (R: red, G: green, B: blue)
4 Pedestal 5 Electrode connecting member 6 Metal wire 7 Light emitting unit 8 Optical multiplexer 9 Input port 10 Optical waveguide 11 Output port 12 Under clad layer 13 Core layer 14 Over clad layer

Claims

a substrate, an optical multiplexer disposed on the substrate and having a plurality of input ports and at least one output port, and a plurality of light sources disposed on the substrate; Each of the light sources is composed of a laser diode and arranged to face each of a plurality of input ports of the optical multiplexer, and the laser diode is attached with an electrode in the combined light generating device, ,
Pedestals each made up of at least one pedestal piece are arranged on the substrate corresponding to the arrangement positions of the plurality of laser diodes, and each of the plurality of laser diodes has its lower surface is placed on the pedestal in contact with the upper surface of the pedestal,
The pedestal is set at a height such that the center of light emission of each of the plurality of laser diodes mounted thereon coincides with the center of the input port of the optical multiplexer arranged facing each laser diode. A synthetic light generating device characterized by:
A substrate, an optical multiplexer disposed on the substrate and having a plurality of input ports and at least one output port, and a plurality of light sources disposed on the substrate, the plurality of light sources is composed of a laser diode, and is arranged to face each of a plurality of input ports of the optical multiplexer, and the laser diode is provided with an electrode. ,
(1) The substrate has a function as an undercladding layer, or an undercladding layer preparation step of laminating an undercladding layer on the substrate;
(2) a core layer forming step of forming a core layer to be an optical waveguide of the optical multiplexer on the undercladding layer after the undercladding layer preparing step;
(3) After the core layer forming step, an optical waveguide forming step of patterning an optical waveguide in the core layer by photolithography using a photomask having a pattern corresponding to the shape of the optical waveguide;
(4) an overcladding layer laminating step of laminating an overcladding layer covering the optical waveguide and the undercladding layer after the optical waveguide forming step;
(5) after the step of laminating the over-cladding layer, etching the over-cladding layer and the under-cladding layer to form a pedestal consisting of at least one pedestal piece for mounting the plurality of laser diodes; a pedestal forming step, wherein the pedestal is formed so as to be arranged corresponding to the arrangement positions of the plurality of laser diodes, and The emission center of each of the laser diodes is set to a height that matches the center of each of the plurality of input ports of the optical multiplexer,
(6) After the pedestal forming step, an electric circuit forming step of providing an electrode connecting material on the pedestal portion and forming a metal wire in order to supply current to the electrode attached to the laser diode;
(7) a laser diode disposing step of disposing the laser diode on the substrate by bringing the lower surface of the laser diode into contact with the upper surface of the pedestal after the electric circuit forming step;
A method for manufacturing a synthetic light generation device, comprising: