WO2017090333A1

WO2017090333A1 - Optical waveguide element and light source module

Info

Publication number: WO2017090333A1
Application number: PCT/JP2016/080404
Authority: WO
Inventors: 正尊安藤; 香川　利雄; 晃広松本; ヴァレリーベリーマン‐ブスケ; ピータージョンロバーツ
Original assignee: シャープ株式会社
Priority date: 2015-11-27
Filing date: 2016-10-13
Publication date: 2017-06-01
Also published as: TW201734525A

Abstract

An optical waveguide element (13) that guides at least three light beams having different wavelengths is provided with: a substrate (15); a plurality of cores (11B, 11R, 11G) that guide the light beams, respectively; and a cladding (17) surrounding around the cores (11B, 11R, 11G). The optical waveguide element has an input end surface (13a) to which the light beams are inputted, and an output end surface (13b) from which the light beams are outputted, and the cores (11B, 11R, 11G) are formed by being separated from each other. Each of the center-to-center distances of the cores (11B, 11R, 11G) on the output end surface (13b) is smaller than each of the center-to-center distances of the cores (11B, 11R, 11G) on the input end surface (13a).

Description

Optical waveguide device and light source module

The present invention relates to an optical waveguide device and a light source module, and more particularly to an optical waveguide device that guides light of a plurality of wavelengths and a light source module using the same.

2. Description of the Related Art Conventionally, as a light source module for an image display device such as a projector or a head mounted display, a light source module that includes a light source that emits blue, green, and red wavelengths and that combines and emits light of a plurality of wavelengths has been proposed. . In addition, as a technique for multiplexing a plurality of lights, one using a planar waveguide (Patent Documents 1 and 2), one using a directional coupler (Patent Document 3), or a multi-wavelength fiber is used. Various types have been proposed, such as those using a dichroic mirror (Patent Document 4).

In a light source module used for an image display device, since light of a plurality of wavelengths is combined to display one image, it is required that the optical axes in the light emission directions of the respective wavelengths are substantially coincident. In particular, the light source module is also required to be downsized when used in a head-mounted display or a small projector.

JP 2005-189385 A JP 2000-329956 A JP 2013-195603 A JP 2013-228651 A JP2015-73139A

For example, in the light source module described in Patent Document 1, light is combined by combining a core corresponding to each wavelength using a branched optical waveguide inside the optical waveguide element, so that one output end is provided. In this method, the optical axes of the respective wavelengths are matched. Further, the optical loss of each wavelength is calculated, and the structure of the optical waveguide portion is set in consideration of the loss of each wavelength. According to this configuration, even if there is a large difference in the light amount of the light source of each wavelength, the light amount at the time of light output corresponding to each wavelength is obtained by intentionally losing the light of the desired wavelength in the optical waveguide element. It is possible to determine in

However, the prior art of Patent Document 1 has a problem that the processing difficulty of the portion where the cores are matched becomes very high. In addition, when considering the use in single mode, it is considered that the higher order mode appears because the core diameter is wide at the joint part where the cores are matched, and even if the core size is reduced after the joint part, It is conceivable that a predetermined amount of light loss occurs in light of a wavelength. Further, there is a possibility that the higher-order mode is output as it is, and in the usage method as a light source module for a projector or the like, there is a possibility that a spot of light occurs on the light irradiation surface and the image is deteriorated.

In the prior art of Patent Document 2, a laser beam printer using an optical waveguide in which the interval between a plurality of cores is narrowed from the light incident end to the light exit end is shown. However, the optical waveguide of Patent Document 2 is used for a laser beam printer, and the interval between the cores at the emission end of the optical waveguide is about 100 μm, and the plurality of lights have substantially the same wavelength. Even if the interval between the plurality of lights is about this level, it can be said that the distance between the plurality of lights is close enough for the application of the laser beam printer in consideration of the image formation state on the surface of the photoreceptor. However, when used in a light source module that combines RGB colors used in an image display device such as for a small projector, there is a problem that the emitted light does not match due to the aberration of the lens that is the optical system, and the image quality deteriorates.

In the prior art of Patent Document 3, a very high processing accuracy is required for the combined portion itself. In addition, considering the loss due to light absorption, there is a problem that further miniaturization is difficult.

In the prior art of Patent Document 4, in order to make the optical axes of the respective wavelengths as close as possible, it is necessary to make the cladding layer of the optical fiber thin. However, the durability of the optical fiber is lowered and it is difficult to handle it as a light source module. There is a problem of becoming.

In the prior art of Patent Document 5, the optical axis of each wavelength must match the point where the light of each wavelength is combined by the dichroic mirror, but the degree of difficulty in adjusting the optical axis is high and the size of the dichroic mirror is limited. There is a problem that downsizing is difficult.

Therefore, the present invention has been made in view of the above problems, and can maintain a single mode and can emit light in a plurality of wavelengths sufficiently close to each other in substantially the same optical axis direction, and can be downsized. An object of the present invention is to provide a possible optical waveguide device and a light source module.

In order to solve the above problems, an optical waveguide device of the present invention is an optical waveguide device that guides a plurality of lights having at least three different wavelengths, and a plurality of waveguides that respectively guide the plurality of lights. And a clad surrounding the periphery of the core, and having an incident end face on which the plurality of lights are incident and an exit end face on which the plurality of lights are emitted, and the plurality of cores are formed apart from each other The center-to-center distance between the plurality of cores at the exit end face is smaller than the center-to-center distance between the plurality of cores at the entrance end face.

In such an optical waveguide device, since a plurality of cores are formed apart from each other, a single mode is maintained, and a plurality of lights are made substantially the same light by reducing the center-to-center distance between the cores at the emission end face. Since it can radiate | emit to an axial direction, size reduction can be achieved.

In one embodiment of the present invention, the plurality of cores may be arranged in a line on the incident end face side, and the central core may guide light having the longest wavelength among the plurality of lights.

In one embodiment of the present invention, at least two of the plurality of cores may have different widths.

Also, in one embodiment of the present invention, the plurality of cores may be configured to have a large width for guiding the light having the longest wavelength.

In order to solve the above-described problems, a light source module of the present invention includes the above-described optical waveguide element, and a plurality of laser diodes that respectively emit the plurality of lights, and between the plurality of laser diodes and the incident end surface. A plurality of first lenses are provided, and a second lens is provided on the emission end face side of the optical waveguide element.

In such a light source module, it is possible to emit a plurality of lights in substantially the same optical axis direction while maintaining a single mode, and even if a lens is provided close to the optical waveguide element, the influence of the optical axis deviation due to aberration can be reduced. Miniaturization can be achieved.

It is possible to provide an optical waveguide element and a light source module that can emit light of a plurality of wavelengths sufficiently close to each other while maintaining a single mode and emit in substantially the same optical axis direction and can be miniaturized.

It is a schematic diagram which shows the projector using the light source module of 1st embodiment. It is a schematic diagram which shows the internal structure of a light source module. It is a perspective view which shows typically the structure of the optical waveguide element of 1st embodiment. FIG. 4A is a plan view, FIG. 4B is an end view on the light incident side, and FIG. 4C is an end surface on the light emitting side. FIG. It is a graph which shows the relationship between the bending radius of the core and the light transmittance in red light, green light, and blue light of 1st embodiment. It is a schematic diagram which shows the relationship of an optical axis when a lens is installed in the vicinity of the output end surface of 1st embodiment. It is a graph which shows the relationship between the width | variety of the clad which exists between each core of 1st embodiment, and an optical coupling distance. It is a graph which shows the relationship between the coupling distance which is the length of the linear area | region of the core of 1st embodiment, and an optical coupling factor. It is a graph which shows the relationship between the width | variety of the clad which exists between each core in the bending part of the core of 1st embodiment, and an optical coupling factor. It is a schematic diagram which shows the structure of the optical waveguide element and light source of 2nd embodiment. It is a schematic plan view of the optical waveguide device of the third embodiment. It is a graph which shows the relationship between the width | variety of the clad which exists between each core in the output end surface of 3rd embodiment, and an optical coupling factor. It is a schematic top view of the optical waveguide element of 4th embodiment. It is an end elevation of the light output side of the optical waveguide device of the fifth embodiment.

(First embodiment)
A first embodiment of an optical waveguide device and a light source module according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a projector which is an image display device using the light source module of the present embodiment. A projector 100 shown in FIG. 1 includes a light source module 1, a drive unit 2, and a MEMS (Micro Electro Mechanical Systems) mirror 3. As shown in FIG. 1, the light L1 emitted from the light source module 1 is reflected by the MEMS mirror 3, projected as light L2, and scanned on a screen (not shown) as the MEMS mirror 3 operates. To produce. During this scanning, the red light, green light, and blue light sources in the light source module 1 are driven in synchronization with the drive unit 2 driving the MEMS mirror 3, and each color at each pixel position on the screen is driven. The color of each pixel is determined by appropriately setting the light intensity ratio of the light beam. A distance measuring device using infrared light may be provided in order to measure the distance from the projector 100 to the screen on which the image is projected.

FIG. 2 is a schematic diagram showing the internal structure of the light source module 1. As shown in FIG. 2, the light source module 1 includes a light source 11B that emits blue light, a light source 11R that emits red light, and a light source 11G that emits green light, and includes

lenses

12B, 12R, and 12G, and an optical waveguide element. 13 and a lens 14 are provided. Light emitted from the

light sources

11B, 11R, and 11G passes through

lenses

12B, 12R, and 12G, which are optical systems, and is incident on the incident end face 13a of the optical waveguide element 13. Here, as blue light, red light, and green light, for example, wavelengths of about 450 nm, 638 nm, and 520 nm can be used, respectively, but other wavelengths may be used.

As will be described later, the light of each color is emitted from the emission end face 13b with the optical axis substantially matched by the optical waveguide element 13, and the emitted light is emitted from the light source module 1 as light L1 collected by the lens 14.

The output of each of the

light sources

11B, 11R, and 11G is adjusted by the drive unit 2. In order to adjust the output of light, a photodiode may be provided inside or outside the light source module 1, and a Peltier element or the like may be provided for temperature adjustment. Each of the

light sources

11B, 11R, and 11G is not particularly limited, but it is desirable to use a laser diode because light needs to be incident on the optical waveguide element. When the output difference among the

light sources

11B, 11R, and 11G is large, a plurality of laser diodes having the same emission wavelength may be used as the light source. The

lenses

12B, 12R, and 12G only need to efficiently make the light emitted from the

light sources

11B, 11R, and 11G incident on the incident end surface 13a, may be a collimator lens, or may be an aspheric lens that reduces aberration. . The lens 14 only needs to be collimated with the light L1 and irradiate the MEMS mirror 3 with a spot as small as possible, and a collimating lens is more preferable. Further, when each light emitted from the adjacent cores of the emission end face 13b has a constant radiation angle, when the light L1 is collimated, the optical axis that has passed through the lens 14 has an angle θ formed as described later. It has a spot center.

FIG. 3 is a perspective view schematically showing the structure of the optical waveguide device 13 of the present embodiment. 4A and 4B are diagrams illustrating the core of the optical waveguide device 13 according to this embodiment. FIG. 4A is a plan view, FIG. 4B is an end view on the light incident side, and FIG. It is an end elevation of the side. As shown in FIGS. 3 and 4, the optical waveguide device 13 includes a substrate 15, cores 16 </ b> B, 16 </ b> R, 16 </ b> G, and a clad 17.

The substrate 15 is a substantially flat member formed of a material such as quartz glass or silicon. The material of the substrate 15 is not particularly limited, but when the same material as that used for the clad 17 is used for the substrate 15, the clad 17 formed below the

cores

16B, 16R, and 16G may not be formed. . Further, when a material having light absorption with respect to the wavelength used, such as Si, is selected as the material of the substrate 15, it is preferable to increase the thickness of the lower clad 17 as appropriate in order to avoid light absorption.

The

cores

16B, 16R and 16G are made of a material having a higher refractive index than that of the clad 17, and the clad 17 is made of a material having a lower refractive index than the

cores

16B, 16R and 16G. The

cores

16B, 16R, and 16G are formed to extend between the incident end face 13a and the outgoing end face 13b, and have a width Cw or the like so as to guide light in a single mode according to the wavelength of the guided light. The radius of curvature is designed. In addition, the

cores

16B, 16R, and 16G have a core 16R that guides red light having the longest wavelength disposed at the center, and the

cores

16B, 16R, and 16G are formed so as not to contact each other and spaced apart from each other by a predetermined distance. Each center distance Db at the exit end face 13b is made smaller than the center distance Da at the entrance end face 13a.

The optical waveguide element 13 may polish the incident end face 13a or may form an antireflection film in order to increase the coupling efficiency of light incident on the optical waveguide element 13 from the outside. Further, in order to increase the extraction efficiency of light emitted to the outside from the optical waveguide element 13, the emission end face 13b may be polished or an antireflection film may be formed. Further, in a predetermined range in the vicinity of the incident end face 13a of the optical waveguide element 13, the cross-sectional sizes of the

cores

16B, 16R, and 16G may be increased in a tapered shape toward the end face. Thereby, the optical coupling efficiency of the

light sources

11B, 11R, 11G and the

cores

16B, 16R, 16G can be increased.

Next, a method for producing the optical waveguide element 13 will be described. The optical waveguide element 13 is usually made of an inorganic glass material mainly composed of SiO ₂ , B ₂ O ₃ , P ₂ O ₅ or the like, or an organic material such as a polymer. May be used. The optical waveguide element 13 uses the above materials for the

cores

16B, 16R, 16G and the cladding 17, and in order to make the refractive index of the

cores

16B, 16R, 16G higher than that of the cladding 17, the composition and / or the composition ratio of each material. The material is selected by changing, adding a dopant, or the like.

As a film forming method, for example, it can be formed by a chemical vapor deposition method, a sputtering method, a flame deposition method, or the like. A conventionally known method for manufacturing a glass waveguide will be described below. First, quartz glass, silicon, or the like is used as the substrate 15, and a glass film to be the lower clad 17 is formed on the substrate 15 so as to have a layer thickness of about 10 μm. Next, a core glass film to be the

cores

16B, 16R, and 16G is formed to have a layer thickness of about 2 μm. Thereafter, unnecessary portions of the core glass film are removed by photolithography and dry etching, and a plurality of optical waveguides are formed in the same plane perpendicular to the stacking direction.

Next, a glass film to be the upper clad 17 is formed to a thickness of about 10 μm, and heat treatment is performed to make the clad 17 layer and the

cores

16B, 16R, and 16G transparent. Thereafter, the substrate 15 and the

cores

16B, 16R, 16G, and the clad 17 formed thereon are diced into predetermined dimensions to obtain the optical waveguide device 13.

In the present embodiment, the width of each of the

cores

16B, 16R, and 16G is 2 μm, and in the vicinity of the emission end face 13b, the

cores

16B, 16R, and 16G are linear regions having a length of about 0.1 mm perpendicular to the emission end face 13b. Is formed. Further, in the linear region in the vicinity of the emission end face 13b, the width of the clad 17 formed between adjacent cores was set to 2 μm.

The intervals between the

cores

16B, 16R, and 16G on the incident end face 13a need to be provided with a predetermined interval Da according to the

light sources

11B, 11R, and 11G to be used. In the optical waveguide device 13, the optical axis of each light emitted from the emission end face 13b is brought close to each other by gradually reducing the interval between the

cores

16B, 16R, and 16G from the incidence end face 13a to the emission end face 13b. Therefore, the

cores

16B, 16R, and 16G are bent between the incident end face 13a and the exit end face 13b as necessary.

In order to guide light efficiently with the optical waveguide element 13, the minimum bending which becomes a bending limit depending on the refractive index difference of the materials used for the

cores

16B, 16R, and 16G and the wavelength of light to be used. There is a radius. If the

cores

16B, 16R, and 16G are bent beyond the minimum bending radius, light leaks to the outer cladding 17, and light cannot be efficiently extracted from the emission end face 13b.

FIG. 5 shows the relationship between the core bend radius and the light transmittance for red light, green light and blue light when the difference in refractive index between the

cores

16B, 16R and 16G and the clad 17 is about 0.5%. As shown in FIG. 5, the minimum bending radius of blue light is about 2.0 mm, the minimum bending radius of green light is about 2.5 mm, and the minimum bending radius of red light is about 5.0 mm. For this reason, when trying to make the optical waveguide element 13 smaller, as in the present embodiment shown in FIG. 3, the longest wavelength red light is guided by the core 16R arranged at the center, and the

adjacent cores

16B and 16G are guided. By making blue light and green light incident on the

cores

16B and 16G, the bending radii of the

cores

16B and 16G can be reduced, and as a result, the optical waveguide element 13 can be made smaller.

When considering using the optical waveguide element 13 in a single mode, the single-mode optical waveguide is generally affected by the refractive index and refractive index difference between the core layer and the cladding layer and the size of the core layer. When each of the

cores

16B, 16R, and 16G intersects, the core width Cw is widened at that portion, and a higher-order mode is generated at the intersecting portion. Even if the core width Cw is reduced after the region where the

cores

16B, 16R, and 16G intersect to make a single mode optical waveguide, the generated higher-order modes cannot exist and light is lost. Accordingly, the

cores

16B, 16R, and 16G extending from the incident end face 13a to the exit end face 13b do not intersect with each other, and are formed apart by a predetermined distance, so that light loss is maintained while maintaining a single mode with light of each color. Can be suppressed.

FIG. 6 is a schematic diagram showing the relationship of the optical axes when the lens 14 is installed in the vicinity of the emission end face 13b. When the distance between the centers of the cores is defined as x (= Db), the installation distance between the emission end face 13b and the lens is defined as u, and the angle formed by the optical axis serving as the center of the spot of light emitted from the adjacent core is defined as θ. x = u × tan θ is satisfied.

When the lens 14 is incorporated in the light source module 1, it is necessary to bring the lens 14 close to the emission end face 13b in order to reduce the size of the apparatus. However, an attempt is made to reduce the angle formed by the optical axis of each light emitted from each core. Then, as is clear from the above formula, it is necessary to reduce the interval x between adjacent cores. In the projector 100, the MEMS mirror 3 is installed at a position about 20 to 30 mm away from the light source module 1, and the emitted light L1 from the light source module 1 enters the MEMS mirror 3. Therefore, the lens 14 needs to be installed at a position closer to the emission end face 13 b of the optical waveguide element 13 than the MEMS mirror 3.

For example, when the lens 14 is installed at a position about 10 mm away from the light source module 1, the optical axis that becomes the center of the spot of light emitted from the adjacent cores is set by setting the distance between the centers of the adjacent cores to about 5 μm or less. Can be suppressed to about 0.03 °. Therefore, by making the interval Db between the

cores

16B, 16R, and 16G as close as possible on the emission end face 13b, the spot centers of the emitted light of each color can be brought close to each other so as to have substantially the same optical axis. By irradiating the light of each color as single-mode light L1 with the center of the spot close, deterioration of the projected image can be suppressed.

In general, when the core interval of the optical waveguide is reduced, optical coupling occurs between the cores, and light guided through a certain core moves to the adjacent core. Also in this embodiment, in order to reduce the distance Db between the

cores

16B, 16R, and 16G on the emission end face 13b, if the distance in the linear region in the vicinity of the emission end face 13b is too small, the light is applied to the adjacent core. The part moves, and light of the same wavelength is emitted from a plurality of places to form a plurality of spots. When the light source module 1 is used in the projector 100, it is difficult to form one pixel when a plurality of spots are irradiated, and the image deteriorates. Therefore, in the optical waveguide device 13 of the present embodiment, it is necessary to provide a predetermined distance for reducing optical coupling between adjacent cores while making the distance Db between the

cores

16B, 16R, and 16G as close as possible at the emission end face 13b.

FIG. 7 is a graph showing the relationship between the width of the clad existing between the cores and the optical coupling distance. The width Cw of each core 16B, 16R, 16G is 2.0 μm. The optical coupling distance is a length until light completely returns to the original core again after the light completely moves to the adjacent core. As shown in FIG. 7, by increasing the width of the clad 17 existing between the cores, the optical coupling distance is increased, and the movement of light between the cores can be made difficult to occur.

FIG. 8 is a graph showing the relationship between the coupling distance, which is the length of the linear region of the core, and the optical coupling rate. The horizontal axis of the graph represents the coupling distance, and the vertical axis represents the optical coupling rate as a relative value of light intensity. The width Cw of each core is 2.0 μm, and the width of the clad 17 existing between them is 2.0 μm. As shown in FIG. 8, when the light guided through a certain core moves a certain distance, the light completely moves to the adjacent core, but by reducing the distance, the amount of movement of the light can be reduced. It is possible to reduce. For example, when red light is guided, the light moves completely to the next core at about 0.7 mm. For example, considering that the movement of light is limited to about 20%, the coupling distance between adjacent cores may be set to 0.2 mm or less, and in order to reduce the movement of light, a linear region where each core is as close as possible. It is better to shorten

As described above, it is preferable that the straight line area in the vicinity of the emission end face 13b is short. However, in order to emit light emitted from the optical waveguide element 13 perpendicularly to the emission end face 13b, it is necessary to provide a certain degree of straight line area. . In addition, a bent portion exists in front of the linear region in the vicinity of the emission end face 13b, but light movement between the cores also occurs in the bent portion.

FIG. 9 is a graph showing the relationship between the width of the clad existing between the cores at the bent portion of the core and the optical coupling rate. The radius of curvature of the

cores

16B and 16G is about 5 mm, and the width of the cladding at the end position of the bent portion where no linear region is provided in the vicinity of the emission end face 13b is shown. As shown in FIG. 9, it can be seen that the light coupling ratio decreases as the width of the clad existing between the cores is increased. For example, in order to suppress the coupling rate to about 5% in red light, the clad width at the bent portion may be set to 2 μm or more.

In order to reduce the light movement between the cores, a plurality of bent portions may be provided by changing the radius of curvature by shortening the linear region of each core. An air trench may be formed in the clad 17 between the cores. Also, the widths of the cores may be set so as not to match. Further, a material having a refractive index different from that of the light reflector, the light absorber, the core, and the clad may be provided between the cores. In addition, as a method of aligning the optical axes of light emitted from each core, optical elements such as a diffractive optical element (DOE) and a microlens array are used to emit the light from each core of the optical waveguide element. The optical axes of light may be closer.

In the optical waveguide element 13 of the present embodiment and the light source module 1 using the optical waveguide element 13, the cores that guide the light of each color are not crossed and are separated by a predetermined distance that suppresses light movement between the cores. The single mode is maintained to reduce optical loss, and light of a plurality of wavelengths can be made sufficiently close to each other and emitted in substantially the same optical axis direction, so that deterioration of image display can be suppressed. Further, by taking an appropriate arrangement corresponding to the light source of each wavelength, the optical waveguide element can be made smaller while suppressing the movement of light between adjacent cores.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a schematic diagram showing the configuration of the optical waveguide device 13 and the light source of the present embodiment. As shown in FIG. 10, in this embodiment, two light sources 11G that emit green light are provided, the corresponding cores 16G are also two, and the optical waveguide element 13 has four cores in total.

In the case where a laser diode is used as the light source 11G, it is difficult to obtain the output of the

light sources

11B and 11G with a single laser diode. Therefore, the total output of green light can be improved by providing a plurality of green light sources 11G. When the

light sources

11B, 11R, and 11G of the respective wavelengths are arranged, if the core 16R that guides the red light having the largest wavelength is arranged at the center, the minimum bending radius of the

cores

16B and 16G is larger than that of the core 16R. Therefore, the optical waveguide element 13 can be downsized. The number of cores of the optical waveguide element 13 is not particularly limited, and may be four or more, and the

cores

16B and 16G may be arranged in any manner as long as the core 16R is located in the center.

Even in the optical waveguide element 13 of the present embodiment and the light source module 1 using the optical waveguide element 13, the cores that guide light of each color are not crossed and are separated by a predetermined distance that suppresses light movement between the cores. The single mode is maintained to reduce optical loss, and light of a plurality of wavelengths can be made sufficiently close to each other and emitted in substantially the same optical axis direction, so that deterioration of image display can be suppressed. Further, by taking an appropriate arrangement corresponding to the light source of each wavelength, the optical waveguide element can be made smaller while suppressing the movement of light between adjacent cores.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a schematic plan view of the optical waveguide element 13 of the third embodiment. In the present embodiment, the width of the core that guides light having a long wavelength is increased. The mode of light to be guided is related to the core width Cw, and the smaller the core width Cw, the easier it becomes a single mode. However, the longer the wavelength of the guided light, the easier it becomes a single mode even if the core size is large. Therefore, in the present embodiment, the core width of the core 16B is 1.8 μm, the core width of the core 16R is 2.0 μm, and the core width of the core 16G is 1.9 μm.

FIG. 12 is a graph showing the relationship between the width of the clad existing between the cores on the emission end face 13b of the present embodiment and the optical coupling rate. As shown in FIG. 12, it can be seen that the light coupling rate decreases as the cladding width between the cores is increased. However, compared with the conditions of the first embodiment, the optical coupling rate is smaller than the cladding width. It is falling. For example, in order to suppress the optical coupling rate to about 5% in red light, the clad width should be about 1.5 μm or more. Thus, by increasing the width of each core 16B, 16R, and 16G as the wavelength of the guided light increases, light movement due to optical coupling between adjacent cores is suppressed, and only a single wavelength from each core is suppressed. It is possible to take out the image and suppress the deterioration of the image.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a schematic plan view of the optical waveguide device 13 of the fourth embodiment. In the optical waveguide device 13 of the first embodiment, the

cores

16B and 16G corresponding to blue light and green light are each bent twice, but in this embodiment, the

cores

16B and 16G are bent once on the side close to the emission end face 13b. . Further, the

cores

16B and 16G are provided to be inclined rather than perpendicular to the incident end face 13a. Thereby, the bending part of the

cores

16B and 16G can be reduced, and the optical waveguide element 13 can be further downsized.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 14 is an end view of the light emitting side of the optical waveguide device 13 of the fifth embodiment. In the first embodiment, the

cores

16B, 16R, and 16G are arranged in a line on the same plane, but in the present embodiment, the

cores

16B, 16R, and 16G are provided with a height difference. By adopting such a core layer arrangement, the interval between the cores on the emission end face 13b can be reduced, and the center of the spots of the emitted light can be made closer to have substantially the same optical axis. It becomes possible.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

This application claims priority based on Japanese Patent Application No. 2015-231439 filed in Japan on November 27, 2015. By referring to this, the entire contents thereof are incorporated into the present application.

According to the present invention, in particular, in the technical field of an optical waveguide element that guides light of a plurality of wavelengths and a light source module using the same, the light of a plurality of wavelengths is made sufficiently close to each other while maintaining a single mode. The light can be emitted in the direction of the optical axis, and downsizing can be realized.

DESCRIPTION OF SYMBOLS 1 ... Light source module 100 ...

Projector

11B, 11R, 11G ...

Light source

12B, 12R, 12G ... Lens 13 ... Optical waveguide element 13a ... Incident end surface 13b ... Outlet end surface 14 ... Lens 15 ...

Substrate

16B, 16R, 16G ... Core 17 ... Cladding 2 ... Drive unit 3 ... MEMS mirror

Claims

An optical waveguide device for guiding a plurality of light beams having different wavelengths,
A substrate, a plurality of cores respectively guiding the plurality of lights, and a clad surrounding the core;
The plurality of lights are incident end faces and the plurality of lights are emitted end faces, the plurality of cores are formed apart from each other;
An optical waveguide device characterized in that a center-to-center distance between the plurality of cores at the exit end face is smaller than a center-to-center distance between the plurality of cores at the entrance end face.
The optical waveguide device according to claim 1,
The plurality of cores are arranged in a line on the incident end face side, and the core in the center guides light having the longest wavelength among the plurality of lights.
The optical waveguide device according to claim 1 or 2,
An optical waveguide device characterized in that at least two of the plurality of cores have different widths.
An optical waveguide device according to any one of claims 1 to 3,
The optical waveguide device, wherein the plurality of cores have a large width for guiding the light having the longest wavelength.
An optical waveguide device according to any one of claims 1 to 4, comprising:
A plurality of laser diodes each emitting the plurality of lights;
A plurality of first lenses provided between the plurality of laser diodes and the plurality of cores of the incident end face;
A light source module comprising a second lens on the light emitting end face side of the optical waveguide element.