JP2015102715A - Optical multiplexer member, light source unit, illumination device, and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical multiplexer member that achieves a reduction in size and can multiplex two or more rays of light at low optical loss.SOLUTION: There is provided an optical multiplexer member that includes a light propagation unit having a plurality of optical paths and an optical multiplexing unit optically coupled to the light propagation unit, where the light propagation unit has a plurality of first cores 2 being the optical paths and a first clad 3 having a lower refractive index than that of the first cores 2 and provided to cover at least two substantially opposing faces of the first cores 2; the optical multiplexing unit has a second core 5 multiplexing rays of light propagated by the light propagation unit and propagating the resulting light and a second clad 6 having a lower refractive index than that of the second core 5 and provided to cover at least two substantially opposing faces of the second core 5; the difference in refractive index between at least one or more first cores 2 and the first clad 3 is smaller than the difference in refractive index between the second core 5 and the second clad 6.

Description

  The present invention relates to an optical multiplexing member, a light source unit, an illumination device, and an image projection device.

  Various proposals have been made as a wavelength multiplexing optical multiplexing device that combines light of different wavelengths emitted from a plurality of light sources (see, for example, Patent Document 1). In Patent Document 1, light emitted from a plurality of light sources is combined in a first fiber multiplexer to form a first combined light from a plurality of fiber combined light source units by a multimode optical fiber. An invention relating to a combined light source that guides wave light and further combines it in a second fiber multiplexer to form second combined light is disclosed. Patent Document 1 provides a combined light source for combining light emitted from a plurality of light sources to obtain combined light with high output and high brightness.

JP 2007-41342 A

However, for example, it is small and used for an endoscope, a small projector (pico projector), a head-mounted display (eyeglass-shaped image projection device), etc. In an illumination device and an image projection device that emit light, it is necessary to mount a miniaturized combined light source. In the combined light source of Patent Document 1, in order to make the light intensity distribution uniform, the propagation path must be lengthened, and the entire apparatus is enlarged.
The present invention has been made in view of solving the above-described problems. An optical multiplexing member, a light source unit, an illuminating device, and an image projecting device capable of multiplexing two or more lights with low optical loss while at the same time achieving miniaturization. The purpose is to provide.

  As a result of diligent research to solve the above-described problems, the present inventors have found that an optical multiplexing member having an optical multiplexing unit optically coupled to an optical propagation unit having a plurality of optical paths, wherein the optical propagation unit A plurality of first cores, which are optical paths that propagate through the first core, and at least two substantially opposing surfaces (for example, both side surfaces) of the first core are covered with a first cladding having a refractive index lower than that of the first core. However, the substantially opposite two surfaces (for example, both side surfaces) of the second core and the second core that propagate by combining light are covered with a second cladding having a refractive index lower than that of the second core. It is found that the above problem can be solved by using an optical multiplexing member in which the difference in refractive index between at least one of the first core and the first cladding is smaller than the difference in refractive index between the second core and the second cladding. It was. The present invention has been completed based on such knowledge.

That is, the present invention
(1) An optical propagation unit having a plurality of optical paths and an optical combining unit optically coupled to the optical propagation unit, the optical propagation unit including a plurality of first cores that are optical paths, and the first core Has a low refractive index and has a first cladding provided to cover at least two substantially opposite surfaces of the first core, and the optical multiplexing unit combines the light propagated by the optical propagation unit. A second core that propagates; and a second cladding that has a refractive index lower than that of the second core and is provided so as to cover at least two substantially opposite surfaces of the second core; An optical multiplexing member in which a refractive index difference between one core and the first cladding is smaller than a refractive index difference between the second core and the second cladding;
(2) The optical multiplexing member according to (1), wherein the entire periphery of each first core has a refractive index lower than that of the first core, and the entire periphery of the second core has a refractive index lower than that of the second core. ,
(3) The optical multiplexing member according to (1) or (2), wherein the second core of the optical multiplexing unit has a tapered portion that reduces an optical axis vertical sectional area with respect to a traveling direction of light,
(4) The optical multiplexing member according to any one of (1) to (3), wherein the refractive indexes of the first cladding and the second core are the same.
(5) The optical multiplexing member according to (4), wherein the first clad and the second core are made of the same material.
(6) The optical multiplexing member according to any one of (1) to (5), wherein the refractive index of the second cladding is smaller than the refractive index of the first cladding.
(7) The optical multiplexing member according to any one of (1) to (4), wherein the materials of the first core and the second core are the same.
(8) The optical multiplexing member according to any one of (1) to (7), wherein the light propagation part and / or the optical multiplexing part is a polymer optical waveguide,
(9) A light source unit using the optical multiplexing member according to any one of (1) to (8),
(10) The light source unit according to (9), including a plurality of light sources that receive light from each of the plurality of first cores,
(11) A lighting device using the light source unit according to (9) or (10),
(12) An image projection device using the light source unit according to (9) or (10),
Is to provide.

  According to the present invention, it is possible to provide an optical multiplexing member, a light source unit, an illuminating device, and an image projecting device that can multiplex two or more lights with low optical loss while achieving miniaturization.

It is a typical top view of the optical multiplexing member concerning a 1st embodiment of the present invention. It is AA sectional drawing of the optical multiplexing member of FIG. It is BB sectional drawing of the optical multiplexing member of FIG. It is a schematic plan view of the optical multiplexing member which concerns on the 2nd Embodiment of this invention. It is CC sectional drawing of the optical multiplexing member of FIG. It is DD sectional drawing of the optical multiplexing member of FIG.

(First embodiment)
As shown in FIG. 1, the optical multiplexing member according to the first embodiment of the present invention has a lower refractive index than a plurality of first cores 2 that propagate light and a first core 2 as a plurality of optical paths. The light propagation part 1 having the first cladding 3 provided so as to cover at least two substantially opposite faces of the first core 2, for example, both side faces, and the light propagated by the light propagation part 1 are combined and propagated The second core 5 and the second cladding 5 having a refractive index lower than that of the second core 5 and provided so as to cover at least two substantially opposite surfaces of the second core 5, for example, both side surfaces, An optical multiplexing unit 4 optically coupled to the propagation unit 1 is provided. The optical multiplexing member of the present invention is characterized in that the refractive index difference between at least one of the first core 2 and the first cladding 3 is smaller than the refractive index difference between the second core 5 and the second cladding 6.

The refractive index difference here is a value represented by the following formula (1).
(Refractive index difference) = (n ₁ ² −n ₂ ² ) ^1/2 / (2 × n ₁ ² ) (1)
* N ₁ ; refractive index of the layer on the high refractive index side, n ₂ ; refractive index of the layer on the low refractive index side, the refractive index difference between at least one of the first core 2 and the first cladding 3 is the second core 5 Since the refractive index difference between the first core 2 and the second cladding 6 is smaller than the first core 2, the light propagated through the first core 2 of the light propagation portion 1 that has been reflected at the interface between the first core 2 and the first cladding 3. Propagating through the optical combining unit 4 while the reflection angle at the interface between the first cladding 3 and the first cladding 3 (the normal formed by the interface between the first core 2 and the first cladding 3 and the angle reflected by the interface) is large. Can do. When light having a large reflection angle propagates to the optical multiplexing unit 4, it is efficiently combined with light propagated from the first core 2 of the other optical propagation unit 1. Since the optical multiplexing unit 4 has a larger refractive index difference than the optical propagation unit 1 that has propagated so far, generation of light components having a small reflection angle results in light components having various reflection angles and is efficiently combined.
In addition, for example, even if an increase in the reflection angle due to reflection at the interface between the second core 5 and the second cladding 6 occurs when propagating the tapered optical combining unit 4 that reduces the spot diameter as shown in FIG. Leakage of light components (stray light) to the second cladding 6 is difficult to occur. In other words, the numerical aperture (NA) of the light propagating through the first core 2 can be reduced, and the generation of higher-order modes can be suppressed. Therefore, stray light to the second cladding 6 due to an increase in NA in the optical multiplexing unit 4 Can be suppressed. For this reason, even if the taper is sharp or the spot diameter is reduced at a short distance, the deterioration of the optical loss can be suppressed, and as a result, the size can be reduced.

  In the present invention, the boundary between the light propagation unit 1 and the optical multiplexing unit 4 is, with respect to the optical axis traveling direction, in the plurality of first cores 2 of the light propagation unit 1 in the embodiment of FIG. It is assumed that the end point of the first core 2 is first reached. That is, in the case of FIG. 1, the end points on the optical multiplexing unit 4 side of the first core 2 may be the same or different from each other.

  In the optical multiplexing member of the present invention, it is preferable that two or more first cores 2 of the light propagation unit 1 are optically coupled to one optical multiplexing unit 4. As a result, light having a large reflection angle at the interface between the first core 2 and the first cladding 3 can be introduced from the respective light propagation units 1 to the optical multiplexing unit 4. Light introduced from the core 2 can be multiplexed.

Hereinafter, each member used for the optical multiplexing member of this invention is demonstrated in detail.

[Light propagation part]
The light propagation part 1 of the present invention has a plurality of first cores 2 and a first cladding 3 as a plurality of optical paths, and the first cladding 3 is disposed so as to cover at least two surfaces substantially opposite to the first core 2. Has been. Further, the light propagation unit 1 is optically coupled to the optical multiplexing unit 4.
The light propagation unit 1 has a plurality of first cores 2 as a plurality of optical paths, but the light that has propagated through the first cores 2 can be multiplexed by the optical multiplexing unit 4. The first core 2 may be two or three, and may be four or more.

  The light propagation part 1 and / or the optical multiplexing part 4 are preferably polymer waveguides. The optical propagation part 1 and / or the optical multiplexing part 4 are polymer waveguides, and the vertical cross-sectional area with respect to the optical axis of the first core 2 and the second core 5 is substantially rectangular, so that the optical propagation part 1 and the optical multiplexing part are combined. The coupling of light with the portion 4 can be improved, and it becomes easy to process their shapes by, for example, photolithography.

[First core]
The first core 2 used in the optical multiplexing member of the present invention is one of light propagation paths for propagating light, has a higher refractive index than the surroundings of the first cladding 3 and the other first cores 2, and propagates. It is preferable to have transparency that does not cause a problem in optical transmission with respect to the wavelength of light to be transmitted.

The first core 2 of the present invention does not need to be entirely covered with the first clad 3, and there is a first clad 3 provided so as to cover at least two substantially opposed surfaces of the first core 2, for example, both side surfaces. Thus, the effect of the present invention can be expressed. When there is a portion without the first clad 3 around the first core 2 of the optical multiplexing member of the present invention, the portion without the first clad 3 has a lower refractive index than that of the first core 2, and thus is favorable. This is preferable because light can be propagated. As an example of the structure that achieves the above, it is possible to cover the portion without the first cladding 3 with a resin having a refractive index lower than that of the first core 2 or an air layer.
The first core 2 may be entirely covered with the first clad 3 or a material having the same refractive index as that of the first clad 3. Specifically, as shown in FIG. 2, the light propagating unit 1 includes the first clad 3 and the (lower) first clad 8 around the first core 2 (all of the upper surface, the lower surface, and both side surfaces). Covering with is preferable because the periphery can be formed with a low refractive index layer.
The refractive index difference between the first core 2 and the first cladding 3 (first cladding 8) is such that the refractive index difference calculated by the above equation (1) is 0.1% or more and 6.0% or less (the following value) 100 from the viewpoint of light confinement and ease of controlling the refractive index of the material, more preferably 1.0% or more and 6.0% or less. More preferably, it is 0% or more and 6.0% or less.

  The shape of the first core 2 from the plan view direction is preferably a substantially straight line and / or a substantially curved line. The above-mentioned substantially straight line / substantially curved line refers to a series of optical paths, not a branched path or a divided optical path. Due to the series of optical paths, the optical loss due to the structure of the light propagating through the first core 2 can be reduced. If the first core 2 is a curve, the position of the light incident portion 10 provided in the first core 2 can be arbitrarily selected, and even light emitting elements that are difficult to be adjacent can be combined with low light loss. it can.

  The width of the first core 2 is preferably 8 μm or more and 1.0 mm or less from the viewpoint that low-loss propagation is possible, and from the viewpoint that light can be efficiently kept in the first core 2, the width is 20 μm or more and 500 μm or more. More preferably, it is more preferably 20 μm or more and 200 μm or less from the viewpoint of reducing the spot diameter of the light emitting portion 16 and obtaining good coupling loss with the light receiving element.

  If the height from the surface of the first clad 8 of the first core 2 is small, a good coupling loss between the light emitting part 11 and the light receiving element is obtained, and if it is large, a good coupling loss between the light incident part 10 and the light emitting element is obtained. Is obtained. From the above viewpoint, the height of the first core 2 is preferably 8 μm or more and 1.0 mm or less, more preferably 20 μm or more and 500 μm or less from the viewpoint of workability, and the viewpoint of workability in photolithography. From the viewpoint of the film formability of the first core-forming resin used therefor, it is more preferably 20 μm or more and 1100 μm or less.

The material for the first core 2 is not particularly limited, and preferable examples include quartz, glass, a silicon substrate, and a resin film that satisfy the above refractive index. When the material of the first core 2 is quartz or glass, a fiber-shaped material can be used, and an optical fiber core wire (portion where light propagates) or the like is preferably used. The material of the first core 2 is more preferably a resin film from the viewpoint of processability to an arbitrary position and shape, and further preferably a material that can be subjected to photolithography, intaglio formation, and injection molding. It is more preferable to use photolithography from the viewpoint that high positional accuracy with other parts can be obtained.
As a photolithography processing method, a first core formed in advance in the form of a layer after applying a first core-forming resin varnish or a first core-forming resin film on the first cladding 8 by laminating, pressing, or the like. There is a method of disposing a pattern forming resist on the forming resin layer, processing the first core 2 into a desired shape by reactive ion etching (RIE) or the like, and then removing the pattern forming resist. . As another photolithography processing method, a photosensitive first core forming resin composition is laminated on the first clad 8 in the same manner as described above, and then a film mask or glass mask on which a desired shape is drawn is used. There is a method of patterning by irradiating actinic rays or drawing directly into a desired shape with actinic rays and removing the uncured first core-forming resin composition with an etching solution.
As a coating method of the varnish-like resin composition, a spin coater, a die coater, a comma coater, a curtain coater, a gravure coater, or the like can be used. The varnish may be formed by previously diluting with a solvent or the like and then applying the varnish by the above method or the like and drying the solvent. As a method for laminating the resin film, it can be laminated by appropriately applying pressure, temperature or the like using a roll laminator, a vacuum roll laminator, a flat plate laminator, a vacuum flat plate laminator, a normal pressure press, a vacuum press or the like.
Further, the photosensitive first core-forming resin composition may be either a negative type in which a site irradiated with actinic light is cured or a positive type in which a site irradiated with actinic light is softened and removed by etching. The kind of etching solution (developer) at this time is not particularly limited, and various solvents, alkaline solutions, mixed solutions thereof and the like are used.

[First cladding]
The first cladding 3 used in the optical multiplexing member of the present invention has a refractive index lower than that of the first core 2, and the refractive index difference between the first core 2 and the refractive index between the second core 5 and the second cladding 6. The refractive index is smaller than the difference.

In the optical multiplexing member of the present invention, it is preferable that the first cladding 3 and the second core 5 have the same refractive index. If the refractive indexes of the first cladding 3 and the second core 5 are the same, the refractive index of the first core 2 is necessarily higher than that, and the refractive index of the second cladding 6 is lower than them. The refractive index difference between the first cladding 3 (same refractive index as the second core 5) and the first core 2 may be made larger than the refractive index difference between the second cladding 6 and the second core 5 (first cladding 3). The number of types of materials having different refractive index differences can be reduced, and the selection of materials becomes easy.
Furthermore, in the optical multiplexing member of the present invention, it is preferable that the materials of the first cladding 3 and the second core 5 are the same. When the first clad 3 and the second core 5 are made of the same material, there is an advantage that the kind of material to be used is reduced, and further, it becomes easy to form the first clad 3 and the second core 5 at the same time. The number of working steps can be reduced, and misalignment between the first cladding 3 and the second core 5 can be suppressed.

[Optical multiplexing section]
The optical multiplexing unit 4 of the present invention has at least a second core 5 and a second cladding 6, and the second cladding 6 is disposed so as to cover at least two substantially opposite surfaces of the second core 5.
It is important that the refractive index difference between the second core 5 and the second cladding 6 calculated by the above formula (1) is larger than the refractive index difference between the first core 2 and the first cladding 3. It is possible to multiplex light incident at a low NA efficiently and with low loss at the optical multiplexing unit 4.

[Second core]
The second core 5 used in the optical multiplexing member of the present invention is one of light propagation paths through which light propagates, and has a refractive index higher than that of the second cladding 6 and the other surroundings of the second core 5 and propagates. It is preferable to have transparency with respect to the wavelength of light so as not to cause a problem in optical transmission.

The second core 5 of the present invention does not need to be entirely covered with the second clad 6, and there is a second clad 6 provided so as to cover at least two substantially opposite surfaces of the second core 5, for example, both side surfaces. Thus, the effect of the present invention can be expressed. When there is a portion without the second clad 6 around the second core 5 of the optical multiplexing member of the present invention, the portion without the second clad 6 has a lower refractive index than that of the second core 5, and thus is favorable. This is preferable because light can be propagated. As a structural example for achieving the above, a method in which a portion without the second cladding 6 is covered with a resin having a refractive index lower than that of the second core 5 or an air layer can be used.
The second core 5 may be entirely covered with a material having the same refractive index as that of the second cladding 6 or the (lower) second cladding 9. Specifically, as shown in FIG. 3, the optical multiplexing unit 4 covers the entire periphery (all of the upper surface, the lower surface, and both side surfaces) of the second core 5 with the second claddings 6 and 9. Can be formed of a layer having a low refractive index.
The refractive index difference between the second core 5 and the second cladding 6 (second cladding 9) is such that the refractive index difference calculated by the above equation (1) is 0.1% or more and 6.0% or less (the following value). 100 from the viewpoint of light confinement and ease of controlling the refractive index of the material, more preferably 1.0% or more and 6.0% or less. More preferably, it is 0% or more and 6.0% or less.
The material and the formation method of the second core 5 can be formed by the same material and method as the first core 2 described above.

  As for the shape of the second core 5 from the plan view direction, the width on the light propagation unit 1 side may be any width that can propagate light from the plurality of first cores 2. What is necessary is just to determine suitably the width | variety by the side of the light emission part 11 of the 2nd core 5 so that it may become arbitrary spot diameters.

It is preferable that the second core 5 of the optical multiplexing part 4 has a taper part 12 that reduces the vertical cross-sectional area of the optical axis with respect to the light traveling direction. By providing the taper part 12, the spot diameter of the light output from the optical multiplexing part 4 can be reduced. In addition, the number of reflections at the interface between the second core 5 and the second cladding 6 can be increased, a plurality of lights can be efficiently combined, and a combined light with uniform intensity can be easily obtained.
From the above viewpoint, the maximum width of the second core 5 is preferably not less than 30 μm and not more than 3.0 mm, more preferably not less than 50 μm and not more than 1500 μm, from the viewpoint that low-loss propagation is possible. From the viewpoint of reducing the spot diameter and obtaining a good coupling loss with the light receiving element, it is more preferably 50 μm or more and 500 μm or less.
The length of the second core 5 in the optical axis direction is not particularly limited, but is preferably 1.0 mm or more and 50 mm or less because uniform combined light is easily obtained and further miniaturization is possible, and 1.0 mm or more and 20 mm or less. It is more preferable that it is 1.0 mm or more and 10 mm or less.
The angle of the tapered portion 12 formed on the second core 5 is not particularly limited as long as it does not adversely affect the light propagation loss, but is preferably 0.01 ° or more and 6.0 ° or less. The angle is more preferably from 0.05 to 4.0 °, and further preferably from 0.1 to 3.5 °.
Moreover, it is preferable to have the 2nd clad 6 which opposes substantially on the taper part 12 formation surface. By doing so, light in which the generation of higher-order modes is efficiently suppressed in the direction of reduction of the spot diameter at the tapered portion 12 can be propagated from the light propagation portion, so that the loss can be reduced.

In the optical multiplexing unit 4 shown in FIG. 3, when the first cladding 8 and the second core 5 are made of the same refractive index material, or the second core 5 is made of a lower refractive index material than the first cladding 8, Since light propagates through a portion where the first cladding 8 and the second core 5 are combined, the second core 5 is defined in a broad sense. At this time, the height from the surface of the second cladding 9 to the upper surface of the second core 5 is preferably 8 μm or more and 1.0 mm or less, and more preferably 20 μm or more and 500 μm or less from the viewpoint of workability. From the viewpoint of workability in lithography and from the viewpoint of the film formability of the second core forming resin used therefor, it is more preferably 20 μm or more and 150 μm or less.
As shown in FIG. 3, it is preferable to arrange the first cladding 8 so as to be embedded by the second core 5, since the cross-sectional shape of the light propagation part 1 becomes a substantially rectangular shape and light can be propagated satisfactorily.

[Second cladding]
The second cladding 6 used in the optical multiplexing member of the present invention has a refractive index lower than that of the second core 5, and the refractive index difference between the second core 5 and the refractive index between the first core 2 and the first cladding 3. The refractive index is larger than the difference.

[substrate]
Since the optical multiplexing member of the present invention has the substrate 7, it has an effect of imparting toughness, rigidity, and flexibility to the optical multiplexing member. When the substrate 7 is not necessary, it may be peeled off in a later step.
From the above viewpoint, examples of the material of the substrate 7 that can be used for the optical multiplexing member of the present invention include a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate, a substrate with a resin layer, and a metal layer. Substrate, plastic film, plastic film with resin layer, plastic film with metal layer, FR-4 substrate, electrical wiring board and the like.

When it is desired to give rigidity to the optical multiplexing member, it is preferable to use a rigid and tough substrate 7 as the substrate 7, for example, a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate. Suitable examples include a substrate with a resin layer, a substrate with a metal layer, an FR-4 substrate, and an electric wiring board.
The thickness of the substrate 7 at this time is not particularly limited, but is preferably 40 μm or more and 10,000 μm or less from the viewpoint of obtaining strength and rigidity as the substrate 7 and obtaining a low-profile optical multiplexing member. More preferably, it is 50 μm or more and 1000 μm or less.

When it is desired to impart flexibility to the optical multiplexing member, it is preferable to use a flexible and tough substrate 7 as the substrate 7, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, Preferred examples include polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyamideimide, and polyimide.
The thickness of the substrate 7 at this time is not particularly limited, but may be 5 μm or more and 200 μm or less from the viewpoint that the strength and flexibility as the substrate 7 can be obtained and a low-profile optical multiplexing member can be obtained. Preferably, it is 10 μm or more and 100 μm or less.

[Light incident part]
A light incident part 10 is provided on the optical axis on the opposite side of the optical multiplexing part 4 of the first core 2 in the light propagation part of the present invention. Thereby, the light incident on the light incident part 10 is propagated to the optical multiplexing part 4, and the respective lights are multiplexed.
In the present invention, a member that makes light incident on the light incident portion 10 is referred to as a light emitting element. For example, as a light emitting element that emits light, an LED, a laser diode, and the like can be given. The light-emitting element is a medium that propagates light and may have a portion that emits light. For example, an optical fiber, an optical waveguide, etc. are mentioned. Further, a lens or the like may be appropriately used between the light emitting elements and the light incident portion 10.
The light used may have different wavelengths or the same wavelength, and examples thereof include infrared light, visible light, and ultraviolet light. If the wavelengths are the same, the amount of light output from the optical multiplexing member can be increased, and if the wavelengths are different, combined light is obtained. When the incident light is visible light, white light is emitted if, for example, blue light of 380 nm to 495 nm, green light of 495 nm to 570 nm, and red light of 620 nm to 750 nm are incident, Depending on the output difference, the hue can be arbitrarily selected.

[Light receiving element]
A light emitting unit 11 is provided on the optical axis of the optical multiplexing unit 4 of the present invention, and the combined light is output from the light emitting unit 11 to the outside of the optical multiplexing member. In the present invention, a member that receives light provided at the tip of the light emitting portion 11 is referred to as a light receiving element. Examples of the light receiving element include a photodiode, an optical fiber, and an optical waveguide. Further, a lens or the like may be appropriately used between the light receiving elements and the light emitting unit 11. The emitted light may be used as a direct illumination or a light source for image projection.
When the optical fiber is used as the light emitting element and the light receiving element, the type of the optical fiber may be a quartz optical fiber or a plastic optical fiber, and may be a step index type or a graded index type. The core diameter of the optical fiber is not particularly limited, but the diameter is preferably 10 μm or more and 1000 μm or less, more preferably 30 μm or more and 200 μm or less, and further preferably 50 μm or more and 150 μm or less. Further, the optical fiber on the light emitting element side and the optical fiber on the light receiving element side may be the same optical fiber or different optical fibers.

(Light source unit)
The light source unit of the present invention is a light source unit using light combined by the above-described optical multiplexing member.
In the light source unit of the present invention, when light sources that emit light of the same wavelength are arranged in two or more light incident portions 10 of the light propagation portion 1, the light intensity can be increased and output. Moreover, the light source unit of this invention can obtain those combined light, if the light source which emits the light of a different wavelength is arrange | positioned in the two or more light-incidence parts 10 of the light propagation part 1. FIG. Specifically, as shown in FIG. 1, the light source unit of the present invention is capable of obtaining white light when light of red, blue, and green wavelengths is incident on each of the three first cores 2. . Furthermore, it is also possible to select a hue by appropriately adjusting their outputs.

(Lighting device, image projection device)
The illumination device and the image projection device of the present invention use the above-described light source unit. As the illumination device of the present invention, for example, by appropriately adjusting the output of light output from the light source unit described above, illumination light having a desired light intensity and hue can be obtained. As an image projection apparatus of the present invention, for example, light output from the above-described light source unit is projected using a reflective liquid crystal or the like, thereby obtaining an image with a desired hue.

(Second Embodiment)
As shown in FIGS. 4 to 6, the optical multiplexing member according to the second embodiment of the present invention has a constituent member of the optical multiplexing unit 4 as compared with the optical multiplexing member according to the first embodiment. Although different 2nd Embodiment is described in full detail below, since description of the location which is substantially the same as the description which concerns on 1st Embodiment becomes a duplicate description, it abbreviate | omits.

  In the present invention, the boundary between the optical propagation unit 1 and the optical multiplexing unit 4 is, in the embodiment of FIG. 4, the optical axis traveling direction in the plurality of first cores 2 of the optical propagation unit 1. First, it is assumed that the boundary of the clad having a different refractive index is reached. That is, in the case of FIG. 4, the end points on the optical multiplexing unit 4 side of the first core 2 may be aligned or different from each other, but the portion after the first boundary is set as the optical multiplexing unit 4.

In the optical multiplexing member of the present invention, the refractive index of the second cladding 6 is preferably smaller than the refractive index of the first cladding 3. When the refractive index of the second cladding 6 is smaller than the refractive index of the first cladding 3, the second core 5 and the second cladding 6 inevitably have a refractive index difference between the first core 2 and the first cladding 3. The refractive index difference of becomes larger.
In the optical multiplexing member of the present invention, the first core 2 and the second core 5 are preferably made of the same material. When the first core 2 and the second core 5 are made of the same material, there is an advantage that the type of material to be used is reduced, and furthermore, it becomes easy to form the first core 2 and the second core 5 at the same time. The number of work steps can be reduced, and misalignment between the first core 2 and the second core 5 can be suppressed.
In the optical multiplexing member of the present invention, the first core 2 and the second core 5 preferably have the same refractive index. When the first core 2 and the second core 5 have the same refractive index, the coupling loss between the first core 2 and the second core 5 can be reduced. Further, if the first core 2 and the second core 5 have the same refractive index, the number of types of materials having different refractive index differences is reduced, and the selection of the material becomes easy.

[Second core]
In the optical multiplexing unit 4 shown in FIG. 6, the second core 5 is formed of a material having a higher refractive index than that of the first cladding 8, and only the second core 5 serves as a light propagation portion. From the above viewpoint, the height from the surface of the first cladding 8 to the upper surface of the second core 5 is preferably 8 μm or more and 1.0 mm or less, and more preferably 20 μm or more and 500 μm or less from the viewpoint of workability. From the viewpoint of workability in photolithography and the film formability of the second core forming resin used therefor, the thickness is more preferably 20 μm or more and 150 μm or less.

  The optical multiplexing member, the light source unit, the illumination device, and the image projection device according to the second embodiment of the present invention are the optical multiplexing member, the light source unit, the illumination device, and the image projection device according to the first embodiment. Similar effects can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
Example 1
<Preparation of resin film A>
[Production of (A) (meth) acrylic polymer (base polymer)]
46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate were weighed and transferred to a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel and a thermometer, and stirred while introducing nitrogen gas. went. The liquid temperature was raised to 65 ° C., 47 parts by weight of methyl methacrylate, 33 parts by weight of butyl acrylate, 16 parts by weight of 2-hydroxyethyl methacrylate, 14 parts by weight of methacrylic acid, 2,2′-azobis (2,4-dimethylvaleronitrile ) A mixture of 3 parts by mass, 46 parts by mass of propylene glycol monomethyl ether acetate, and 23 parts by mass of methyl lactate was added dropwise over 3 hours, followed by stirring at 65 ° C. for 3 hours. Further, stirring was continued at 95 ° C. for 1 hour to obtain a solution of (A) (meth) acrylic polymer (solid content: 45 mass%).

[Measurement of weight average molecular weight]
(A) As a result of measuring the weight average molecular weight (in terms of standard polystyrene) of (meth) acrylic polymer using GPC (“SD-8022”, “DP-8020”, “RI-8020” manufactured by Tosoh Corporation), 3 9 × 10 ⁴ . As the column, “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd. were used.
[Measurement of acid value]
As a result of measuring the acid value of (A) (meth) acrylic polymer, it was 79 mgKOH / g. The acid value was calculated from the amount of 0.1 mol / L potassium hydroxide aqueous solution required to neutralize the (A) (meth) acrylic polymer solution. At this time, the point at which the phenolphthalein added as an indicator changed color from colorless to pink was defined as the neutralization point.

[Preparation of resin varnish A]
As a base polymer, (A) (meth) acrylic polymer solution (solid content 45 mass%) 84 mass parts (solid content 38 mass parts), (B) Urethane (meth) acrylate having a polyester skeleton as a photocuring component (new) 33 parts by mass of “U-200AX” manufactured by Nakamura Chemical Co., Ltd., and 15 parts by mass of urethane (meth) acrylate having a polypropylene glycol skeleton (“UA-4200” manufactured by Shin-Nakamura Chemical Co., Ltd.), (C) thermosetting As a component, 20 parts by mass of a polyfunctional block isocyanate solution (solid content: 75% by mass) obtained by protecting an isocyanurate type trimer of hexamethylene diisocyanate with methyl ethyl ketone oxime (“Sumijour BL3175” manufactured by Sumika Bayer Urethane Co., Ltd.) 15 parts by weight), (D) As a photopolymerization initiator, 1- [4 (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (“Irgacure 2959” manufactured by BASF Japan Ltd.) 1 part by mass, bis (2,4,6-trimethylbenzoyl) 1 part by mass of phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) and 23 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent for dilution were mixed with stirring. After pressure filtration using a polyflon filter having a pore size of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.), degassing was performed under reduced pressure to obtain a resin varnish A.

[Preparation of Resin Film A]
The resin varnish A obtained above was coated on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) as a support film. TM-MC "), and after drying at 100 ° C for 20 minutes, a surface release-treated PET film (" Purex A31 "manufactured by Teijin DuPont Films Ltd., thickness 25 μm) is pasted as a protective film, and a resin film A was obtained.
At this time, the thickness of the resin layer formed from the resin varnish A can be arbitrarily adjusted by adjusting the gap of the coating machine.

[Measurement of refractive index]
The 50 μm resin film A obtained above with the protective film peeled off is placed on a silicon substrate (size 60 × 20 mm, thickness 0.6 mm) with a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.). After vacuuming to 500 Pa or less, lamination was performed under conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a pressurization time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated with 2000 mJ / cm ² with an ultraviolet exposure machine, the support film was peeled off, and further heated at 160 ° C. for 1 hour to prepare a sample for refractive index measurement. The refractive index of the sample at a wavelength of 830 nm was measured using a prism-coupled refractometer (“Model 2020” manufactured by Metricon). The refractive index of the cured resin layer was 1.496.

<Preparation of resin film B>
(A) As a base polymer, 26 parts by mass of phenoxy resin (“Phenototo YP-70” manufactured by Toto Kasei Co., Ltd.), (B) As a photopolymerizable compound, 9,9-bis [4- (2-acryloyloxyethoxy) ) Phenyl] fluorene (Shin Nakamura Chemical Co., Ltd. “A-BPEF”) 36 parts by mass, bisphenol A type epoxy acrylate (Shin Nakamura Chemical Co., Ltd. “EA-1020”) 36 parts by mass, (C) Hikari As a polymerization initiator, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) and 1- [4- (2-hydroxyethoxy) phenyl]- 2-Hydroxy-2-methyl-1-propan-1-one (manufactured by BASF Japan Ltd., “Irgacure 295 ") 1 part by mass to prepare a resin varnish B in the same manner and conditions as the formulation of the above-described resin varnish A, except for using 40 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent. Thereafter, pressure filtration and degassing under reduced pressure were performed in the same manner and conditions as described above.
The resin varnish B obtained above was coated and dried in the same manner as in the above production example on the non-treated surface of a PET film (“Cosmo Shine A1517” manufactured by Toyobo Co., Ltd., thickness 16 μm) as a support film. Subsequently, a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was attached as a protective film so that the release surface was on the resin side, and a resin film B was obtained.
At this time, the thickness of the resin layer formed from the resin varnish B can be arbitrarily adjusted by adjusting the gap of the coating machine, and the film thickness after drying will be described later.

[Measurement of refractive index]
When the refractive index of the cured resin layer was measured by the same method as described above, the refractive index was 1.577.

<Preparation of resin film C>
[Base polymer for forming resin film C; production of (meth) acrylic polymer (P-1)]
42 parts by mass of propylene glycol monomethyl ether acetate and 21 parts by mass of methyl lactate were weighed and transferred to a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel and a thermometer, and stirred while introducing nitrogen gas. went. The liquid temperature was raised to 65 ° C., 14.5 parts by mass of N-cyclohexylmaleimide, 20 parts by mass of benzyl acrylate, 39 parts by mass of O-phenylphenol 1.5EO acrylate, 14 parts by mass of 2-hydroxyethyl methacrylate, 12. After dropping a mixture of 5 parts by mass, 4 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile), 37 parts by mass of propylene glycol monomethyl ether acetate, and 21 parts by mass of methyl lactate over 3 hours, 65 ° C. For 3 hours. Furthermore, stirring was continued at 95 ° C. for 1 hour to obtain a (meth) acrylic polymer (P-1) solution (solid content: 45% by mass).
As a result of measuring the acid value and the weight average molecular weight of the P-1 solution by the same method as described above, they were 80 mg KOH / g and 32,000, respectively.

[Preparation of resin varnish C]
(A) As an alkali-soluble (meth) acrylic polymer containing a maleimide skeleton in the main chain, 60 parts by mass of P-1 solution (solid content: 45% by mass), (B) as a polymerizable compound, ethoxylated bisphenol A diacrylate (Hitachi) 15 parts by mass of “Fancryl FA-324A” (“Fancril” is a registered trademark) manufactured by Kasei Co., Ltd. and 15 parts by mass of ethoxylated bisphenol A diacrylate (“Fancryl FA-321A” manufactured by Hitachi Chemical Co., Ltd.), phenol 10 parts by mass of a biphenylene type epoxy resin (“NC-3000” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 275 g / eq), (C) 1- [4- (2-hydroxyethoxy) phenyl] -2 as a polymerization initiator -Hydroxy-2-methyl-1-propan-1-one (“Irgacure” manufactured by BASF Japan Ltd.) 959 ") 1 part by mass, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (" Irgacure 819 "manufactured by BASF Japan Ltd.) is weighed into a wide-mouthed plastic bottle, and using a stirrer, Resin varnish C was prepared by stirring for 6 hours under the conditions of a temperature of 25 ° C. and a rotational speed of 400 min ⁻¹ . Then, using a polyflon filter having a pore diameter of 2 μm (“PF020” manufactured by Toyo Roshi Kaisha, Ltd.) and a membrane filter having a pore diameter of 0.5 μm (“J050A” manufactured by Toyo Roshi Kaisha, Ltd.), a temperature of 25 ° C. and a pressure of 0.4 MPa. And filtered under pressure. Subsequently, defoaming was performed under reduced pressure for 15 minutes using a vacuum pump and a bell jar under conditions of a reduced pressure of 50 mmHg to obtain a resin varnish C.

[Preparation of Resin Film C]
The resin varnish C was applied to a non-treated surface of a PET film (Toyobo Co., Ltd. “A1517”, thickness 16 μm) using a coating machine (Hirano Techseed Co., Ltd. multi-coater “TM-MC”), After drying at 100 ° C. for 20 minutes, a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was attached as a protective film to obtain a resin film C. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine.

[Measurement of refractive index]
When the refractive index of the cured resin layer was measured by the same method as described above, the refractive index was 1.555.

<Example of production of optical multiplexing member in FIG. 1>
[Formation of the second cladding 9]
A 100 mm × 100 mm polyimide film (polyimide “Kapton EN” manufactured by Toray DuPont Co., Ltd., thickness 25 μm) is used as the substrate 7, and the protective film of the resin film A having a thickness of 15 μm obtained above is applied to one surface. After peeling, using a vacuum pressure laminator ("MVLP-500" manufactured by Meiki Seisakusho Co., Ltd.) and vacuuming to 500 Pa or less, then under conditions of pressure 0.4 MPa, temperature 90 ° C, pressurization time 30 seconds Lamination was performed by thermocompression bonding. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm ² from the support film side of the resin film A using an ultraviolet exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.). Thereafter, the support film was peeled off, dried and cured at 170 ° C. for 1 hour, and the second cladding 9 was formed.

[Formation of the first cladding 8]
Next, the resin film C having a thickness of 15 μm obtained above is peeled off from the surface on which the second clad 9 is formed as described above, and then the roll laminator (HLM-1500 manufactured by Hitachi Chemical Technoplant Co., Ltd.) is peeled off. )) Under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C. and a laminating speed of 0.2 m / min, and then using the above-mentioned vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) After vacuuming below, thermocompression bonding was performed under the conditions of a pressure of 0.4 MPa, a temperature of 70 ° C., and a pressurization time of 30 seconds.

Subsequently, a 220 μm × 0.5 mm rectangle is connected to the light propagation part 1 forming part, a 220 μm side is connected to the light combining part 4 forming part, and the base is reduced to 7 mm × 90 μm (a trapezoid having an upper side of 90 μm and a lower side of 220 μm). A negative photomask having an opening having a shape was irradiated with ultraviolet rays (wavelength 365 nm) at 2500 mJ / cm ² from the support film side of the resin film C using the ultraviolet exposure machine. Thereafter, the support film is peeled off, the uncured resin film C is removed using a developing solution (1% potassium carbonate aqueous solution), then washed with water, dried and cured by heating at 160 ° C. for 1 hour, A clad 8 was formed. The thickness of the first cladding 8 was 15 μm.

[Formation of the first core]
After peeling off the protective film of the resin film B having a thickness of 65 μm obtained above on the first clad 8 formation surface obtained above, a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) After vacuuming to 500 Pa or less, lamination was performed by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 65 ° C., and a pressing time of 30 seconds. Subsequently, using an ultraviolet exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.), a negative photomask having 50 μm × 7.5 mm × 3 (80 μm pitch) openings was used. Then, after aligning the first clad 8 having a rectangular shape of 200 μm × 7.5 mm previously formed so as to be arranged, the ultraviolet ray (wavelength 365 nm) is irradiated at 0.8 J / cm ² , and then 80 ° C. And after exposure for 5 minutes, heating was performed. Thereafter, the PET film as the support film was peeled off and etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and it heat-dried at 100 degreeC for 10 minute (s), and formed the three 1st cores 2 patterned. The thickness of the obtained second core 6 was 50 μm.

[Formation of first cladding and second core]
After peeling off the protective film of the resin film C having a thickness of 75 μm obtained above from the surface on which the first core 2 is formed, a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) is used and the pressure is 500 Pa. After vacuuming below, lamination was performed by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 90 ° C., and a pressing time of 30 seconds. Subsequently, a 230 μm × 7.501 mm rectangle is connected to the light propagation part 1 forming part, and a 230 μm side is connected to the optical multiplexing part 4 forming part, and reduced to 7.01 mm × 100 μm (upper side is 100 μm and lower side is 230 μm trapezoid). The negative-type photomask having the trapezoidal opening is aligned so that the opening includes the first cladding 8, and using an ultraviolet exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.) Ultraviolet rays (wavelength 365 nm) were irradiated at 2500 mJ / cm ² from the support film side of the resin film C. Thereafter, the support film was peeled off, dried and cured at 170 ° C. for 1 hour using a 1% aqueous potassium carbonate solution, and the first cladding 2 and the second core 5 were formed simultaneously. The height of the obtained first cladding 2 from the surface of the second cladding 9 was 60 μm.
Further, the second core 5 included the first clad 8 of the previously formed optical multiplexing part 4 formation part.

[Formation of second cladding]
After peeling off the protective film of the resin film A having a thickness of 100 μm obtained above from the surface on which the second core 5 is formed, a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) is used and the pressure is 500 Pa. After vacuuming below, lamination was performed by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 90 ° C., and a pressing time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm ² from the support film side of the resin film C using an ultraviolet exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.). Thereafter, the support film was peeled off, dried and cured at 170 ° C. for 1 hour, and the second cladding 5 was formed.

[Formation of light incident part and light emission part]
A dicing saw (“DAC552” manufactured by DISCO Corporation) having a light dicing blade 10 at a position of 14.0 mm in the optical axis direction from the light incident portion 10 of the optical multiplexing member obtained above. Then, the substrate 7 was cut together and the end face was smoothed to form the light incident part 10 and the light emitting part 11.

[Optical loss measurement]
From the light incident part 10 provided in the first core 2 of the obtained optical multiplexing member, light having a wavelength of 850 nm is incident and emitted from the light emitting part 11 using a GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element. The received light was received using an optical fiber of SI114 as a light receiving element, and optical loss was measured. As a result, the optical loss input from the central first core 2 and output from the light emitting unit 11 is 1.8 dB, and the optical loss input from the first core 2 at both ends and output from the light emitting unit 11 is 2 8 dB.

[Evaluation of light uniformity]
Using the GI50 optical fiber as a light emitting element, 405 nm blue, left and right 532 nm green, and 632 nm red were incident from the light incident portion 10 provided on the first core 2 of the obtained optical multiplexing member. When the hue of the light emitting portion 11 was seen from the direction opposite to the optical axis, the white color was uniform and good.
Note that the light output region of the light emitting unit 11 was the second core 5 and the first cladding 8.

(Example 2)
<Example of production of optical multiplexing member in FIG. 4>
In Example 1, after forming the second clad 9 using the resin film A, the resin film C is used as the first clad 8 to form the light propagation portion 1 in a 240 μm × 7.501 mm rectangle, optical multiplexing. A trapezoid pattern that is connected to a side of 240 μm at the part 4 formation site and is reduced to 7 mm × 110 μm (a trapezoid with an upper side of 110 μm and a lower side of 240 μm) is formed using the resin film B, and the first core 2 and the second core 5 to 50 μm × 0.5 mm × 3 first cores 2 (80 μm pitch) and a width of 230 μm connected to the three first cores 2, 7.0 μm to 100 μm (upper side is 100 μm (light emitting part) 11 side), the second core 5 having a taper portion that is reduced to a lower side (a trapezoid whose three first cores 2 side are 230 μm) is formed, and resin film C is used to form 50 μm × 7.5 mm × 3 pieces. ( The first cladding 3 of 220 μm × 7.5 mm covering the first core 2 with a pitch of 0 μm) was formed, and the second cladding 6 covering the first cladding 3 and the second core 5 was formed using the resin film A. .
Then, the external shape process was performed similarly to Example 1, and the optical multiplexing member shown in FIG. 4 was formed.

[Optical loss measurement]
From the light incident part 10 provided in the first core 2 of the obtained optical multiplexing member, light having a wavelength of 850 nm is incident and emitted from the light emitting part 11 using a GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element. The received light was received using an optical fiber of SI114 as a light receiving element, and optical loss was measured. As a result, the optical loss input from the central first core 2 and output from the light emitting unit 11 is 1.8 dB, and the optical loss input from the first core 2 at both ends and output from the light emitting unit 11 is 3 .1B.

[Evaluation of light uniformity]
Using the GI50 optical fiber as a light emitting element, 405 nm blue, left and right 532 nm green, and 632 nm red were incident from the light incident portion 10 provided on the first core 2 of the obtained optical multiplexing member. When the hue of the light emitting portion 11 was seen from the direction opposite to the optical axis, the white color was uniform and good.

(Comparative Example 1)
In Example 1, an optical multiplexing member was formed by the same method except that the first core 2 was not formed.

[Optical loss measurement]
An optical fiber of GI 50 having a cladding diameter of 80 μm is used as a light emitting element from the light incident part 10 to the second core 5 of the obtained optical multiplexing member (the place where the light incident part of the first core 2 was present in Example 1). Then, light having a wavelength of 850 nm was incident, the light emitted from the light emitting portion 11 was received using an optical fiber of SI114 as a light receiving element, and the optical loss was measured. As a result, the light loss input from the location where the first core 2 at the center is present and the optical loss output from the light emitting portion 11 is 3.6 dB, and the light loss is input from the location where the first core 2 at both ends is present. The optical loss output from was 5.2 dB.

(Comparative Example 2)
In Example 2, an optical multiplexing member was formed by the same method except that the first cladding A2 was not formed.

[Optical loss measurement]
Using the GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element, light having a wavelength of 850 nm is incident on the second core 5 in Example 1 of the obtained optical multiplexing member from the light emitting unit 11. The emitted light was received using an optical fiber of SI114 as a light receiving element, and optical loss was measured. As a result, the optical loss input from the central first core 2 and output from the light emitting unit 11 is 2.8 dB, and the optical loss input from the first core 2 at both ends and output from the light emitting unit 11 is 4 2 dB.

  The optical multiplexing member of the present invention is an optical multiplexing member capable of obtaining a combined light in which two or more lights are combined with low optical loss while at the same time reducing the size. Various optical devices, various optical combining devices, and light sources It can be applied to a wide range of fields such as units, optical interconnections, medical / industrial endoscopes, illumination devices such as various measuring machines, image projection devices such as projectors, pico projectors, and head mounted displays.

DESCRIPTION OF SYMBOLS 1 ... Light propagation part 2 ... 1st core 3 ... 1st clad 4 ... Optical multiplexing part 5 ... 2nd core 6 ... 2nd clad 7 ... Substrate 8 ... (lower part) 1st clad 9 ... (lower part) 2nd clad 10 ... light incident part 11 ... light emitting part

Claims (12)

A light propagation part having a plurality of optical paths and an optical multiplexing part optically coupled to the light propagation part;
The light propagation portion includes a plurality of first cores that are optical paths, and a first cladding that has a refractive index lower than that of the first core and is provided so as to cover at least two substantially opposite surfaces of the first core. And
The optical multiplexing unit has a second core that multiplexes and propagates the light propagated by the optical propagation unit, and has a refractive index lower than that of the second core, and covers at least two substantially opposite surfaces of the second core. A second cladding provided as follows:
An optical multiplexing member in which a refractive index difference between at least one of the first core and the first cladding is smaller than a refractive index difference between the second core and the second cladding.   2. The optical multiplexing member according to claim 1, wherein the entire periphery of each first core has a refractive index lower than that of the first core, and the entire periphery of the second core has a refractive index lower than that of the second core.   3. The optical multiplexing member according to claim 1, wherein the second core of the optical multiplexing unit has a tapered portion that reduces an optical axis vertical cross-sectional area with respect to a traveling direction of light.   The optical multiplexing member according to any one of claims 1 to 3, wherein the first cladding and the second core have the same refractive index.   The optical multiplexing member according to claim 4, wherein the first clad and the second core are made of the same material.   The optical multiplexing member according to claim 1, wherein a refractive index of the second cladding is smaller than a refractive index of the first cladding.   The optical multiplexing member according to claim 1, wherein the first core and the second core are made of the same material.   The optical multiplexing member according to claim 1, wherein the light propagation part and / or the optical multiplexing part is a polymer optical waveguide.   A light source unit using the optical multiplexing member according to claim 1.   The light source unit according to claim 9, comprising a plurality of light sources that receive light from each of the plurality of first cores.   An illumination device using the light source unit according to claim 9.   An image projection apparatus using the light source unit according to claim 9.