JP2015102714A - 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 has two first cores 1, and a second core 2 having a junction part 7 that is arranged in a first gap 9 formed by the two first cores 1 and joins at least a part of the first cores 1 and having a lower refractive index than that of the first cores 1, where the first gap 9 has a tapered shape reduced in width toward a direction of travel of light D of the first cores 1.

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 becomes large.
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 intensive studies to solve the above-described problems, the present inventors have found that two or more first cores have a first gap between at least one first core narrowing in the light traveling direction of the first core. A second core having a tapered portion and having a refractive index lower than that of the first core is disposed in the first gap, and at least a part of the side surface of the second core is an optical multiplexing member that joins the first core. The present inventors have found that the above problems can be solved. The present invention has been completed based on such knowledge.

That is, the present invention
(1) The first core includes a joining portion that is disposed in a first gap formed by at least two first cores and the two first cores and that joins at least a part of the first core. A second core having a low refractive index, and an optical multiplexing member having a tapered shape in which the first gap is narrowed toward the light traveling direction of the first core,
(2) The side wall of the first core that is not opposed to the second core has a light traveling direction so as to reduce an optical axis vertical cross-sectional area composed of the two first cores and the second core in the joint portion. The optical multiplexing member according to (1) having a gradient toward
(3) The optical multiplexing member according to (1) or (2), wherein the joint portion has both side surfaces of the second core joined to the two first cores, respectively.
(4) The optical multiplexing member according to any one of (1) to (3), which includes a non-joined portion in which the two first cores and the second core are not joined.
(5) The optical multiplexing member according to any one of (1) to (4), wherein a minimum width of the first gap is equal to or less than a width of the two first cores.
(6) The first core and the second core are formed on a lower cladding layer having a refractive index lower than that of the first core and the second core, and / or from the first core and the second core. The optical multiplexing member according to any one of (1) to (5), embedded in an upper cladding layer having a low refractive index,
(7) A side surface of the two first cores of the joint opposite to the side surface joined to the second core is in contact with a low refractive index portion having a lower refractive index than the second core (1). The optical multiplexing member according to any one of to (6),
(8) The optical multiplexing member according to (7), wherein the low refractive index portion is an upper cladding layer,
(9) There is a third core in which the two first cores and the second core are optically connected together in the light traveling direction of the two first cores and the second core. ) The optical multiplexing member according to any one of
(10) The optical multiplexing member according to (9), having a second gap between the two first cores or / and the second core and the third core,
(11) The light respectively incident on the two first cores is combined by the third core, and the light incident on the two first cores and the light incident on the second core. Are combined at the joint or / and the third core (9) or the optical multiplexing member according to (10),
(12) The width of the connection portion of the third core that is optically connected to the two first cores and the second core is greater than a maximum width of the two first cores and the second core. The optical multiplexing member according to any one of (9) to (11), which is 2 times or more and 3 times or less.
(13) A light source unit using the optical multiplexing member according to any one of (1) to (12),
(14) A lighting device using the light source unit according to (13),
(15) An image projection device using the light source unit according to (13),
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 top view which shows the one aspect | mode of the optical multiplexing member which concerns on embodiment of this invention. It is AA sectional drawing of the optical multiplexing member shown in FIG. It is BB sectional drawing of the optical multiplexing member shown in FIG. It is CC sectional drawing of the optical multiplexing member shown in FIG. It is a top view which shows the comparative example of the optical multiplexing member of this invention.

(Optical multiplexing member)
The optical multiplexing member according to the embodiment of the present invention has at least two first cores that are optical paths. As shown in FIG. 1, each of the two first cores 1 is a series of optical paths. The second core is disposed in the first gap 9 formed between the two first cores 1. The second core 2 has a joint 7 that joins at least a part of the two first cores 1. The second core 2 has a lower refractive index than the two first cores 1. The first gap 9 has a tapered shape that narrows in the light traveling direction D of the two first cores 1.

  In the optical multiplexing member of the present invention, the third core 3 in which the two first cores 1 and 2 are optically connected together in the light traveling direction D of the two first cores 1 and the second core 2. It is preferable to have. By having the third core 3, the light propagated through the two first cores 1 and the second core 2 can be multiplexed more uniformly in the third core 3. Furthermore, if the third core 3 has a tapered shape that changes the spot diameter, the spot diameter of the combined light can be changed to an arbitrary size. By shrinking the spot diameter, a smaller output light source can be formed, contributing to the miniaturization of the optical unit.

The first core 1 and the second core 2 of the optical multiplexing member of the present invention are formed on the lower cladding layer 4 having a refractive index lower than that of the first core 1 and the second core 2 as shown in FIGS. Or / and embedded in the upper cladding layer 5 having a lower refractive index than the first core 1 and the second core 2. Thereby, there is an advantage that the position of the first core 1 and the second core 2 can be held by the lower clad layer 4 and / or the upper clad layer 5 and the advantage that the first core 1 and the second core 2 can be protected.
As shown in FIG. 4, the third core 3 of the optical multiplexing member of the present invention is formed on the lower cladding layer 4 having a refractive index lower than that of the third core 3 and / or has a refractive index higher than that of the third core 3. It is preferable to be buried in the lower upper cladding layer 5. Accordingly, there is an advantage that the position of the third core 3 can be held by the lower clad layer 4 and / or the upper clad layer 5 and an advantage that the third core 3 can be protected.
The lower cladding layer 6 is preferably provided on the substrate 6.

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

[First core]
The first core 1 used in the optical multiplexing member of the present invention is one of light propagation paths through which light propagates, and there are at least two, which are more refracted than the second core 2, the lower cladding layer 4, and the upper cladding layer 5. It is desirable that the rate is high and the transparency of the light to propagate does not cause a problem in optical transmission.
The refractive index difference between the first core 1 and the second core 2, the lower cladding layer 4, and the upper cladding layer 6 is such that the refractive index difference represented by the following formula (1) is 0.1% or more. It is preferably 0% or less (the following value is multiplied by 100), and is 1.0% or more and 6.0% or less from the viewpoint of optical confinement and the ease of controlling the refractive index of the material. Is more preferably 2.0% or more and 6.0% or less.
(Refractive index difference) = (n ₁ ² −n ₂ ² ) ^1/2 / (2 × n ₁ ² ) (1)
* N ₁ ; refractive index of the high refractive index side layer, n ₂ ; refractive index of the low refractive index side layer

  The shape of the first core 1 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 1 can be reduced. It is preferable that the first core 1 is a curved line because the joint portion 7 and the non-joint portion 8 of the first core 1 and the second core 2 can be easily designed. When the first core 1 is a curve, the radius of curvature is preferably 4 mm or more and 50 mm or less from the viewpoint of miniaturization in order to suppress optical loss due to bending. More preferably, they are 8 mm or more and 30 mm or less, More preferably, they are 10 mm or more and 20 mm or less.

  The width of the first core 1 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 1, the width is 20 μm or more and 500 μm or less. More preferably, it is more preferably 20 μm or more and 200 μm or less from the viewpoint of reducing the spot diameter at the connection portion 15 with the third core 3 and obtaining good coupling loss with the light receiving element.

In the optical multiplexing member of the present invention, the side of the first core 1 that does not face the second core 2 so as to reduce the vertical cross-sectional area of the optical axis composed of the two first cores 1 and the second core 2 in the joint portion 7. It is preferable that the side wall has a gradient 11 toward the light traveling direction D. The optical axis vertical cross-sectional area including the two first cores 1 and the second core 2 refers to the total area of the optical axis vertical cross sections of the two first cores 1 and the second core 2. As a result, the spot diameter of the light emitted from the two first cores 1 and the second core 2 can be further reduced, and the loss can be reduced. Further, the gradient 11 may be a taper.
When providing the gradient 11 in the 1st core 1, it is preferable that it is a core width within said range. The angle of the gradient 11 is not particularly limited as long as it does not adversely affect the optical loss, but is preferably 0.1 ° to 3.0 °, preferably 0.5 ° to 2.0 °. More preferably, it is 0.5 ° or more and 2.0 ° or less.

  It is preferable that the two first cores 1 be disposed at substantially line-symmetrical positions with respect to the center line of the second core 2 because the two first cores 1 can be disposed on both sides of the second core 2. Further, as shown in FIGS. 1 and 3, it is preferable that both side surfaces of the second core 2 have joint portions 7 that are respectively joined to the two first cores 1 disposed on both sides of the second core 2. By having the joint portions 7 where the two first cores 1 are joined on both sides of the second core 2, the two first cores 1 can be brought close to each other, and the second cores 2 are clad layers of the first cores 1. Therefore, a total of three light spot diameters (distance between the outer side surfaces of the first core 1 and the other first core 1) propagating through the two first cores 1 and the second core 2 are reduced. can do. As a result, the spot diameter of the emission composed of the two first cores and the second core can be reduced even if three cores are used, and the loss can be reduced. Further, the projected image of the output light is combined during the projection and close to a uniform distribution, and when an optical path for making uniform light such as the third core 3 is further arranged, the coupling loss with them is lost. There is an advantage that can be suppressed.

  Furthermore, in the present invention, as shown in FIGS. 1 and 2, the non-joint portion 8 in which the first core 1 and the second core 2 are not joined to at least a part of the first core 1 and the second core 2. It is preferable to have. By having the non-joining part 8, the pitch between the respective cores can be changed without largely changing the core width of the two first cores 1 and / or the core width of the second core 2. Thereby, even if it is difficult to make a plurality of light emitting elements for entering light into the light incident portion 13 adjacent to each other, it is possible to multiplex them with low light loss.

  If the height from the surface of the lower cladding layer 4 of the first core 1 is small, a good coupling loss between the light emitting portion 14 and the light receiving element is obtained, and if it is large, a good coupling loss between the light incident portion 13 and the light emitting element is obtained. Is obtained. From the above viewpoint, the height of the first core 1 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 200 μm or less.

The width of the first gap 9 between the two first cores 1 is not particularly limited. However, when the third core 3 is not provided, the portion with the smallest width is the most light traveling direction side of the member. In the case where the third core 3 is provided, it is preferable that the third core 3 is closest to the third core 3 side. If the minimum width of the first gap 9 is equal to or smaller than the width of the first core 1 forming the minimum width, the two first cores and the second core can be brought close to each other, and thus the uniformity of the light of the projected image is improved. When the third core 3 is provided, the spot diameter of the light emitting portion 14 can be reduced with low loss.
The minimum width of the first gap 9 is preferably less than or equal to the width of the first core 1. Thereby, the 1st core 1 formed in the both sides of the 2nd core 2 can be made to approach further, and the spot diameter of the radiation which consists of the 1st core and the 2nd core can be made smaller than mentioned above, Loss can be reduced.
The first gap 9 is preferably 5 μm or more because the pattern shape can be satisfactorily formed when the first core 1 and the second core 2 are formed by etching. From the above viewpoint, the first gap 9 is preferably 5 μm or more and 1.0 mm or less, more preferably 10 μm or more and 500 μm or less, further preferably 10 μm or more and 100 μm or less, and 10 μm or more and 50 μm or less. Most preferred.

The optical multiplexing member of the present invention preferably has a second gap 10 between the two first cores 1 or / and the second core 2 and the third core 3. By disposing, for example, a lens or the like in the second gap 10, it is possible to suppress coupling loss.
In addition, when the first core 1 and the second core 2 are formed by etching, if there is no second gap 10, etching residue, meandering or peeling of the first core 1 is likely to occur. It is preferable to have two gaps 10. By having the second gap 10, the flow of the etching solution becomes good, and between the two first cores 1, between the two first cores 1 and the third core 3, and between the second core 2 and the third core 3. The resolution becomes good. The second gap 10 may be filled with an air layer or a resin. In the latter case, the second gap 10 may be filled with the upper cladding layer 5.
The width of the second gap 10 (width in the optical axis direction) is not particularly limited as long as it does not adversely affect the optical loss, but is preferably 5 μm or more and 400 μm or less, and preferably 10 μm or more and 300 μm or less. More preferably, it is 10 μm or more and 100 μm or less.

As shown in FIG. 1, the optical multiplexing member of the present invention is a joint portion 7 in two first cores 1, and the side surface opposite to the side surface joined to the second core 2 is from the second core 2. Is preferably in contact with a low refractive index portion having a low refractive index. The low refractive index portion is preferably the upper clad layer 5 because it can be formed of the same material as the protection of the first core 1 and the second core 2 and the low refractive index portion can be formed at the same time.
By contacting the low refractive index portion, even if light propagating through the second core 2 leaks to the first core 1 at the junction 7, it is prevented from leaking from the side surface of the first core 1 on the low refractive index portion side. Therefore, light can be propagated with low optical loss. Furthermore, the joint surface between the first core 1 and the second core 2 and the joint surface between the first core 1 and the low refractive index portion are non-parallel, or the first core 1 is a core having a curve. Even in some cases, the occurrence of light loss due to light leakage can be similarly suppressed.

The material for the first core 1 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 1 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 1 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 a layer shape after applying a first core-forming resin varnish or a first core-forming resin film on the lower cladding layer 4 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 1 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 lower clad layer 4 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.
In addition, the photosensitive first core forming resin composition may be a negative type in which a portion irradiated with actinic rays is cured, or a positive type in which a portion irradiated with actinic rays is softened and removed by etching. Good. 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.

[Second core]
The second core 2 used in the optical multiplexing member of the present invention is one of light propagation paths through which light propagates, has a lower refractive index than the first core 1, and is lower than the lower cladding layer 4 and the upper cladding layer 5. It is preferable that the refractive index is high and the light has a transparency that does not cause a problem with respect to the wavelength of propagating light.
The refractive index difference between the first core 1, the second core 2, the lower cladding layer 4, and the upper cladding layer 6 is such that the refractive index difference represented by the above formula (1) is 0.1% or more and 6.0%. Or less, more preferably 1.0% or more and 6.0% or less, and more preferably 2.0% or more and 6.0% from the viewpoint of light confinement and the ease of controlling the refractive index of the material. More preferably, it is as follows.

  The shape of the second 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 means that the second core 2 is not a branch path or a divided optical path but a series of optical paths. Since the second core 2 is a series of optical paths, optical loss due to the structure of light propagating through the second core 2 can be reduced. It is preferable that the second core 2 is a straight line because the joint portion 7 and the non-joint portion 8 between the first core 1 and the second core 2 can be easily designed. In addition, you may provide a taper and a gradient in the 2nd core 2 suitably.

  The width of the second core 2 is preferably 5 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 efficiently remain in the second core 2, the width is 7 μm or more and 500 μm or less. More preferably, it is more preferably 10 μm or more and 200 μm or less from the viewpoint of reducing the spot diameter at the joint portion with the third core 3 and obtaining a good coupling loss with the light receiving element.

  If the height from the surface of the lower cladding layer 4 of the second core 2 is small, a good coupling loss between the light emitting part 14 and the light receiving element can be obtained, and if it is large, a good coupling between the light incident part 13 and the light emitting element is obtained. Loss is obtained. From the above viewpoint, the height of the second 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 second core forming resin used therefor, it is more preferably 20 μm or more and 200 μm or less.

  The difference in height between the first core 1 and the second core 2 is preferably as small as possible from the viewpoint of coupling with the third core 3 and suppressing uneven brightness and color unevenness in the projected image. From the above viewpoint, the difference in height between the first core 1 and the second core 2 is preferably 0 μm or more and 25 μm or less, more preferably 0 μm or more and 15 μm or less, and 0 μm or more and 10 μm or less. Further preferred.

  The material for the second core 2 is not particularly limited, and the same material as that for the first core 1 can be used. Moreover, there is no limitation in particular as a formation method of the 2nd core 2, It can form by the method similar to the 1st core 1. FIG.

The first core 1 and the second core 2 of the present invention may be formed of the same material as long as the above refractive index difference can be secured. It is preferable that the first core 1 and the second core 2 are made of the same material because a difference in height between the first core 1 and the second core 2 can be suppressed.
When forming the first core 1 and the second core 2 in different steps, the first core 1 is formed after the second core 2 is formed even if the second core 2 is formed after the first core 1 is formed. May be. At this time, the height difference between the formed first core 1 and second core 2 may be within the above-described range.
When forming the first core 1 and the second core 2 in different steps, for example, as shown in FIG. 3, if the second core 2 is formed after forming the first core 1, a part of the second core 2 becomes the first Although most of the light propagating through the second core 2 propagates in the first core 1 or the second core 2 sandwiched between the first cores 1, the light is disposed on the first core 1. Therefore, there is no particular problem. Although not shown, when the first core 1 is formed after the second core 2 is formed, a part of the first core 1 is disposed on the second core 2. In this case, As in the former, since most of the light propagating through the first core 1 propagates through the first core 1 arranged on both sides of the second core 2, there is no particular problem. It is assumed that a first gap 9 exists between the first cores 1.

[Third core]
As shown in FIGS. 1 and 4, the third core 3 used in the optical multiplexing member of the present invention is formed on the optical axes of the two first cores 1 and the second core 2, and the two first cores 1. And a core for multiplexing the light propagated from the second core 2 in the third core 3. The third core 3 only needs to have transparency within a range that does not adversely affect the wavelengths of the light propagating through the two first cores 1 and the light propagating through the second core 2. From the above viewpoint, the material of the third core 3 can be the same material as that of the first core 1 and the second core 2. Alternatively, the first core 1 and the second core 2 may be formed of polymer optical waveguides, and an optical fiber or the like may be used as the third core 3.

The shape of the third core 3 from the plane direction may be linear or curved, and may have a taper that changes its vertical cross-sectional area in the light traveling direction. It is preferable that the third core 3 has a taper that reduces the cross-sectional area because the spot diameter of the light output from the light emitting portion 14 can be reduced. By reducing the spot diameter, it is possible to reduce the size of the light source unit, the illumination device, and the image projection device.
The third core 3 shown in FIG. 1 is embedded in the cladding layer (the lower cladding layer 4 and the upper cladding layer 5 in the figure). It is preferable that the third core 3 is embedded in the cladding layer because the position of the third core 3 can be easily fixed. Furthermore, as shown in FIG. 1, it is preferable to form the third core 3 on the lower cladding layer 4 because the height alignment with the first core 1 and the second core 2 becomes easy.

  When the height of the third core 3 is small, a good coupling loss between the light emitting portion 14 and the light receiving element is obtained, and when the height of the third core 3 is large, the first core 1 and the second core 2 are obtained. And a good coupling loss. From the above viewpoint, the height of the third core 3 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 workability in photolithography is improved. From the viewpoint and the viewpoint of the film formability of the third core-forming resin used therefor, it is more preferably 20 μm or more and 200 μm or less. The difference in thickness between the third core 3 and the first core 1 or the second core 2 is that the coupling loss between the first core 1 and the second core 2 and the third core 3 can be reduced. It is preferably from −25 μm to +25 μm, more preferably from −15 μm to +15 μm, and even more preferably from −10 μm to +10 μm.

  The width of the connecting portion 15 of the third core 3 is preferably as small as possible within a range that can receive light from the two first cores 1 and 2 and does not adversely affect optical loss. From the above viewpoint, the width of the connecting portion 15 of the third core 3 is preferably 25 μm or more and 3.0 mm or less, more preferably 50 μm or more and 1.5 mm or less, and 50 μm or more and 600 μm or less. More preferably, it is most preferably 50 μm or more and 150 μm or less.

Further, within the above range, the width of the connecting portion 15 of the third core 3 is larger than the maximum width of the two first cores 1 and 2 (the maximum core width of the three cores). It is preferable that it is 2 times or more and 3 times or less (the value of a / b in FIG. 1 including the left and right values). If the width of the connecting portion 15 of the third core 3 is within the above range, the advantage that the spot diameter can be made small and propagated to the third core 3 with low loss, the third core 3 can achieve uniform uniformity. Even when a taper for reducing the spot diameter is provided in the third core 3, the light can be propagated with low loss, and even if the taper for reducing the spot diameter is provided in the third core 3, the light is output from the light emitting part 14. The obtained light has good uniformity, and there is an advantage that interference fringes are less likely to occur and / or an advantage that it is difficult to visually recognize. Moreover, in order to express said effect more notably, it is more preferable that the width | variety of the connection part 15 of the 3rd core 3 is 2.2 times or more and less than 3 times, and is about 2.4 times and less than 3 times. More preferably.
The substantial maximum width in the first core 1 and the second core 2 in the present invention is a width in which light can substantially propagate even when, for example, the first core 1 has a protrusion or a recess at the connection point 15. Say. In other words, the width does not take into account protrusions, dents, and the like.

The connection portion 15 in the present invention represents the first entrance where the lights propagated through the three cores (the two first cores 1 and the second core 2) are mixed, and in FIG. The end surface on the first core 1 (or second core 2) side is represented.
Even if it is the connection part 15 in the optical multiplexing member shown in FIG. 5, if it is in said value, the same effect will be acquired. When the optical multiplexing member having three gaps between the three cores as shown in FIG. 5 and the three cores are formed of the same material, the position where the cores first diverge in the direction opposite to the light traveling direction, or The end point of the third core 3 (the end surfaces on the side of the three cores) is defined as a connection portion 15 in the direction opposite to the light traveling direction. However, when the optical multiplexing member as shown in FIG. 5 is formed by etching, it is difficult to achieve the above value because etching residue is likely to occur in the gap. Therefore, the structure of the optical multiplexing member of the present invention shown in FIG. 1 is preferable.

[Lower cladding layer]
The lower cladding layer 4 used for the optical multiplexing member of the present invention has a refractive index lower than that of the first core 1 and the difference in refractive index from the first core 1 is preferably within the range of the above formula (1). As shown in FIGS. 2 and 3, by forming the first core 1 and the second core 2 on the lower clad layer 4, the first core 1 and the second core 2 having desired shapes are formed at desired positions. it can. Further, as shown in FIG. 4, the third core 3 may be formed on the same lower cladding layer 4. It is preferable to form the first core 1, the second core 2, and the third core 3 on the same lower clad layer 4 because it is easy to adjust the height of each core.

[Upper clad layer]
The upper cladding layer 5 used in the optical multiplexing member of the present invention has a lower refractive index than the first core 1 and the second core 2, and the refractive index difference between the first core 1 and the second core 2 is the above formula ( It may be within the range of 1).
The upper cladding layer 5 is preferably embedded so as to cover at least the upper surface and further the side surfaces of the first core 1 and the second core 2. As shown in FIGS. 1 and 2, there is no problem even if the first core 1 is covered with a material having the same refractive index as that of the second core 2 at the non-joint portion 8. By embedding the first core 1 and the second core 2 with the upper cladding layer 5, the N.I. A. An increase in (numerical aperture) can be suppressed, and light leakage from the first core 1 to the second core 2 can be suppressed. Further, as shown in FIG. 4, by embedding the third core 3 with the upper clad layer 5, it becomes possible to propagate light having a small spread to the third core 3, and thus it is possible to suppress deterioration of optical loss. .
The upper cladding layer 5 covering the first core 1, the second core 2, and the third core 3 may be the same or different. The lower cladding layer 4 and the upper cladding layer 5 may have the same refractive index, different refractive indexes, the same material, or different materials.

[substrate]
Since the optical multiplexing member of the present invention has the substrate 6, it has an effect of imparting toughness, rigidity, and flexibility to the optical multiplexing member. When the substrate 6 is not necessary, it may be removed in a later step.
From the above viewpoint, the material of the substrate 6 that can be used for the optical multiplexing member of the present invention includes, for example, 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 6 as the substrate 6, 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 6 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 6 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 substrate 6 having flexibility and toughness as the substrate 6, 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 6 at this time is not particularly limited, but may be 5 μm or more and 200 μm or less from the viewpoint of obtaining strength and flexibility as the substrate 6 and a low-profile optical multiplexing member. Preferably, it is 10 μm or more and 100 μm or less.

[Light incident part]
A light incident portion 13 is provided on the optical axis of the first core 1 and the second core 2 of the present invention in the direction opposite to the light traveling direction. The light incident on the light incident portion 13 is propagated to the joint portion 7. Furthermore, when it has the 3rd core 3, the light which injected into the light-incidence part 13 is propagated to the 3rd core 3, and is combined.
In the present invention, a member that makes light incident on the light incident portion 13 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 13.
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.

  The optical multiplexing member of the present invention can obtain uniform light by projecting from a light source that is brought close to the optical multiplexing member. The optical multiplexing member has a third core 3, and light incident on the two first cores 1 is respectively The light that is combined at the third core 3 and incident on the two first cores 1 and the light that is incident on the second core 2 may be combined at the junction 7 and / or the third core 3. preferable. Thereby, it can multiplex within the housing | casing of an optical multiplexing member.

[Light receiving element]
Among the optical multiplexing members of the present invention, when the third core 3 is provided, a light emitting part 14 is provided on the optical axis of the third core 3 in the light traveling direction D, and the light emitting part 14 The emitted light is output outside the optical multiplexing member. In the optical multiplexing member of the present invention, when the third core 3 is not provided, the light emitting part 14 is provided on the optical axis in the light traveling direction D of the first core 1 and the second core 2, and the light emission is performed. From the unit 14, the combined light is output outside the optical combining member.
In the present invention, a member that receives light provided at the tip of the light emitting portion 14 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 14. 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 disposed in the light incident portions 13 of the two first cores 1 and 2, the light intensity can be increased and output. Moreover, the light source unit of this invention can obtain those combined lights, if the light source which emits light of a different wavelength is arrange | positioned in the light incident part 13 of the two 1st cores 1 and the 2nd cores 2. FIG. Specifically, as shown in FIG. 1, the light source unit of the present invention mixes light with red, blue, and green wavelengths into the two first cores 1 and 2 respectively, and the light is mixed and white light is mixed. Can be obtained. 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.

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 a resin film for forming a cladding layer>
[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 for forming clad layer]
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 diameter of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.), degassing was performed under reduced pressure to obtain a resin varnish for forming a cladding layer.

[Preparation of resin film for forming clad layer]
The coating varnish (manufactured by Hirano Techseed Co., Ltd.) is applied to the non-treated surface of the PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) as a support film. Multi-coater “TM-MC”) is applied and dried at 100 ° C. for 20 minutes, and then a surface release-treated PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) is applied as a protective film. A resin film for forming a cladding layer was obtained.
At this time, the thickness of the resin layer formed from the clad layer resin varnish can be arbitrarily adjusted by adjusting the gap of the coating machine.

[Measurement of refractive index]
The 50 μm clad layer-forming resin film obtained above with the protective film peeled off is vacuum-pressurized laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) on a silicon substrate (size 60 × 20 mm, thickness 0.6 mm). )) And evacuated to 500 Pa or less, and then laminated 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 first and third core forming resin films>
(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 ”) First and third core-forming resin varnishes in the same manner and under the same conditions as the above-mentioned preparation of the cladding layer-forming resin varnish, except that 1 part by weight and 40 parts by weight of propylene glycol monomethyl ether acetate were used as the organic solvent. Was formulated. Thereafter, pressure filtration and degassing under reduced pressure were performed in the same manner and conditions as described above.
The first and third core-forming resin varnishes obtained above were placed on the non-treated surface of a PET film (“Cosmo Shine A1517” manufactured by Toyobo Co., Ltd., thickness 16 μm) as a support film, After applying and drying in the same manner, a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) as a protective film is applied so that the release surface is on the resin side. A resin film for forming a third core was obtained.
At this time, the thickness of the resin layer formed from the first and third core-forming resin varnishes 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 1.577.

<Production of second core-forming resin film>
[Second Core-Forming Base Polymer; 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 for forming second core]
(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, The resin varnish for forming the second core was prepared by stirring for 6 hours under the conditions of a temperature of 25 ° C. and a rotation 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 second core-forming resin varnish.

[Preparation of second core-forming resin film]
Using the above-mentioned second core-forming resin varnish on a non-treated surface of a PET film (“A1517” manufactured by Toyobo Co., Ltd., thickness 16 μm) using a multi-coater “TM-MC” manufactured by Hirano Techseed Co., Ltd. And then dried at 100 ° C. for 20 minutes, and then a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was applied as a protective film to obtain a resin film for forming a second core. . 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 lower cladding layer]
A 100 mm × 100 mm polyimide film (polyimide “Kapton EN” manufactured by Toray DuPont Co., Ltd., thickness: 25 μm) was used as the substrate 6, and the resin film for forming a clad layer having the thickness of 15 μm obtained above was formed on one surface. After peeling off the protective film, after vacuuming to 500 Pa or less using a vacuum pressurization laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.), pressure 0.4 MPa, temperature 90 ° C., pressurization time 30 seconds. The film was laminated by thermocompression bonding under the following conditions. Then, the ultraviolet-ray (wavelength 365nm) was irradiated by 3000 mJ / cm < ² > from the support film side of the resin film for clad layer formation using the ultraviolet exposure machine (Oku Seisakusho "EXM-1172"). Thereafter, the support film was peeled off, dried and cured at 170 ° C. for 1 hour, and a lower cladding layer 4 having a thickness of 15 μm was formed.

[Formation of first core and third core]
After the protective film of the resin film for forming the first and third cores 1 having a thickness of 50 μm obtained above is peeled off from the surface on which the lower clad layer 4 is obtained as described above, a vacuum pressure laminator (name machine Co., Ltd.) After vacuuming to 500 Pa or less using “MVLP-500” manufactured by Seisakusho, the film was laminated by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 65 ° C., and a pressurization time of 30 seconds. Subsequently, using a UV exposure machine (“EXM-1172” manufactured by Oak Manufacturing Co., Ltd.), a negative photomask on which desired shapes of the first core 1 and the third core 3 are drawn (the finished shape will be described later). ) Was placed, irradiated with ultraviolet rays (wavelength 365 nm) at 0.8 J / cm ² , and then after exposure at 80 ° C. 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 heat-dried at 100 degreeC for 10 minute (s), and patterned.
The obtained first cores 1 are approximately S-shaped with a radius of curvature of 15 mm, a length of 3.33 mm, and are arranged so that the minimum first gap is 20 μm, and further in each light traveling direction D. The shape was such that the width was reduced from 50 μm to 40 μm (the first gap was kept at 20 μm) (the distance between the light incident portions 13 of the two first cores 1 was 250 μm).
The obtained third core 3 is formed of the same material as that of the first core 1 and has a width of 100 μm on the first core 1 and the second core 2 side, a length of 3.165 mm, and a width of 80 μm on the light emitting part side. Thus, the shape has a taper (the width of the second gap 10 between the first core 1 and the third core 3 is 50 μm).

[Formation of second core]
After peeling the protective film of the second core-forming resin film having a thickness of 55 μm obtained above from the first core 1 forming surface side, 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 90 ° C., and a pressing time of 30 seconds. A negative photomask (the finished shape will be described later) on which a desired shape of the second core 2 is drawn is arranged and aligned, 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. Thereafter, the support film was peeled off, etched with a 1% aqueous potassium carbonate solution, dried and cured at 170 ° C. for 1 hour, and the second core 2 was formed.
The second core 2 is a substantially straight line having a length of 2.33 mm and a taper of 50 μm to 35 μm in width, and is arranged in the center of the first gap 9 (a part of the second core 2 is the first core). 1 and the second core 2 is reduced to a width of substantially 50 μm to 20 μm). In the non-joint portion 8 of the first core 1, the second core forming material is disposed as a part of the upper cladding layer 5 so as to cover the first core 1. The value of a / b was 2.5.

[Formation of upper cladding layer]
After peeling off the protective film of the 100 μm-thick clad layer forming resin film obtained above from the second core 2 forming surface side, a vacuum pressure laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.) is used. 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 90 ° C., and a pressurization time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm ² from the support film side 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 upper clad layer 5 was formed.

[Formation of light incident part and light emission part]
A dicing saw (stock) provided with a rectangular dicing blade at a position to be the light incident portion 13 of the obtained optical multiplexing member and a position to be a light emitting portion 14 of 6.5 mm in the optical axis direction from the light incident portion 13. The entire substrate 6 was cut using “DAC552” manufactured by DISCO Co., Ltd., and the end face was smoothed to form the light incident portion 13 and the light emitting portion 14.

[Optical loss measurement]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, infrared light having a wavelength of 850 nm is incident using a GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element. The light emitted from the light emitting portion 14 was received using an optical fiber of SI114 as a light receiving element, and the optical loss was measured. As a result, the optical loss input from the second core 2 located at the center and output from the light emitting unit 14 is 2.5 dB, and the optical loss input from the first core 1 at both ends and output from the light emitting unit 14 The average was 1.3 dB.

[Evaluation of light uniformity]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, using the optical fiber of GI50 as a light emitting element, the central second core 2 has a blue color of 405 nm, left and right The first core 1 was incident with 532 nm green and 632 nm red. When the hue of the light emitted from the light emitting portion 14 from the direction opposite to the optical axis was observed, the white color was uniform and good. When the projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projection image was observed, the white color was uniform and good. There were no interference fringes.

(Example 2)
In Example 1, a dicing saw (“DAC552” manufactured by DISCO Corporation) provided with a rectangular dicing blade at a position where the light emitting unit 14 is 3.33 mm in the optical axis direction from the light incident unit 13. The whole substrate 6 was cut and the end face was smoothed to form an optical multiplexing member without the third core 3.

[Evaluation of light uniformity]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, using the optical fiber of GI50 as a light emitting element, the central second core 2 has a blue color of 405 nm, left and right The first core 1 was incident with 532 nm green and 632 nm red. When the projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projection image was observed, the white color was uniform and somewhat good. There were no interference fringes.

(Example 3)
In the first embodiment, the first gap 9 is widened (width 39 μm), the width of the third core 3 on the first core 1 side is increased (width 119 μm), and the a / b value is 2.975 (first core 1 An optical multiplexing member was formed in the same manner except that the maximum width was 2.38).

[Optical loss measurement]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, infrared light having a wavelength of 850 nm is incident using a GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element. The light emitted from the light emitting portion 14 was received using an optical fiber of SI114 as a light receiving element, and the optical loss was measured. As a result, the optical loss input from the second core 2 located at the center and output from the light emitting unit 14 is 2.9 dB, and the optical loss input from the first core 1 at both ends and output from the light emitting unit 14 The average was 1.8 dB.

[Evaluation of light uniformity]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, using the optical fiber of GI50 as a light emitting element, the central second core 2 has a blue color of 405 nm, left and right The first core 1 was incident with 532 nm green and 632 nm red. When the color of the light emitting portion 14 was seen from the direction opposite to the optical axis, the white color was uniform and good. When the projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projection image was observed, the white color was uniform and good. There were no interference fringes.

Example 4
In the first embodiment, one first core 1 is not provided with a gradient (width 50 μm), the other first core 1 is provided with a gradient of 20 μm (minimum width 30 μm), and the a / b value is 2 (first core 1 An optical multiplexing member was formed in the same manner except that the maximum width was 2.5).

[Optical loss measurement]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, infrared light having a wavelength of 850 nm is incident using a GI50 optical fiber with a cladding diameter of 80 μm as a light emitting element. The light emitted from the light emitting portion 14 was received using an optical fiber of SI114 as a light receiving element, and the optical loss was measured. As a result, the optical loss input from the second core 2 located at the center and output from the light emitting unit 14 is 2.7 dB, and the optical loss input from the first core 1 at both ends and output from the light emitting unit 14 The average was 1.6 dB. There was variation in the optical loss at both ends.

[Evaluation of light uniformity]
From the light incident part 13 provided in the first core 1 and the second core 2 of the obtained optical multiplexing member, using the optical fiber of GI50 as a light emitting element, the central second core 2 has a blue color of 405 nm, left and right The first core 1 was incident with 532 nm green and 632 nm red. When the color of the light emitting portion 14 was seen from the direction opposite to the optical axis, the white color was uniform and good. When the projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projection image was observed, the white color was uniform and good. There were no interference fringes.

(Comparative Example 1)
<Example of production of optical multiplexing member in FIG. 5>
In Example 1, the first core 1 was not formed, but the following cores (the parts corresponding to the first core 1, the second core 2, and the third core 3 in Example 1) were formed by the second core 2. Except for the above, an optical multiplexing member was formed in the same manner.
1. Bending radius 15mm, length 3.33mm, width 50μm, line symmetrical shape, 2 locations Length 3.33mm, width 50μm
3. 3. The three cores are arranged with a minimum gap of 20 μm. 4. The light incident portions 13 are each 125 μm apart. A portion corresponding to the third core 3 (b ′ / a) having a tapered portion that decreases in width from 190 μm to 80 μm (light emitting portion 13) with a length of 3.165 mm in the light traveling direction of the three cores (with a gap of 50 μm). 'Is 3.8)

[Optical loss measurement]
From the light incident portion 13 of the second core 2 of the obtained optical multiplexing member (where the light incident portions 13 of the first core and the second core 2 existed in Example 1), an optical fiber with a cladding diameter of 80 μm and a GI 50 is used. Infrared light having a wavelength of 850 nm was used as a light emitting element, and light emitted from the light emitting unit 14 was received using an optical fiber of SI114 as a light receiving element, and light loss was measured. As a result, the optical loss input from the second core 2 located at the center and output from the light emitting unit 14 is 3.6 dB, and the optical loss input from the second core 2 at both ends and output from the light emitting unit 14 Was 4.5 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 13 provided on the second core 2 of the obtained optical multiplexing member. When the color of the light emitting portion 14 was seen from the direction opposite to the optical axis, the white color was uniform and good. When a projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projected image was observed, color unevenness occurred. Interference fringes were also generated in the vertical direction (vertical direction of the substrate).

(Comparative Example 2)
In Comparative Example 1, the substrate was cut from the light incident part 13 at a position where the light emitting part 14 having a size of 3.33 mm in the optical axis direction was formed, and an optical multiplexing member without the third core 3 was formed. Other than that, an optical multiplexing member was formed by the same method as in Comparative Example 1.

[Evaluation of light uniformity]
Using the GI50 optical fiber as a light emitting element, 405 nm blue, 532 nm green, and 632 nm red were incident from the light incident portion 13 provided on the first core 1 of the obtained optical multiplexing member. When the projection plate was placed at a position 5 cm away from the light emitting portion 14 and the projected image was observed, color unevenness was slightly observed.

The optical multiplexing member of the present invention is an optical multiplexing member that can combine three lights with low optical loss while achieving miniaturization. Various optical devices, various optical multiplexing devices, light source units, optical interconnection, medical The present invention can be applied to a wide range of fields such as industrial and 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 ... 1st core 2 ... 2nd core 3 ... 3rd core 4 ... Lower clad layer 5 ... Upper clad layer 6 ... Substrate 7 ... Joint part 8 ... Non-joint part 9 ... 1st gap | interval 10 ... 2nd gap | interval 11 ... Gradient 13 ... light incident part 14 ... light emitting part 15 ... connecting part

Claims (15)

At least two first cores;
A second core disposed in a first gap formed by the two first cores, having a joint for joining to at least a part of the first core, and having a lower refractive index than the first core. ,
An optical multiplexing member having a tapered shape in which the first gap narrows in the light traveling direction of the first core.   The side wall of the first core that is not opposed to the second core is directed in the light traveling direction so as to reduce the vertical cross-sectional area of the two first cores and the second core at the joint. The optical multiplexing member according to claim 1, which has a gradient.   3. The optical multiplexing member according to claim 1, wherein both the side surfaces of the second core are joined to the two first cores, respectively.   The optical multiplexing member according to any one of claims 1 to 3, further comprising a non-joined portion in which the two first cores and the second core are not joined.   The optical multiplexing member according to any one of claims 1 to 4, wherein a minimum width of the first gap is equal to or less than a width of the two first cores.   The first core and the second core are formed on a lower clad layer having a lower refractive index than the first core and the second core, and / or have a refractive index higher than that of the first core and the second core. The optical multiplexing member according to any one of claims 1 to 5, which is embedded in an upper clad layer having a low height.   The side surface opposite to the side surface joined to the second core in the two first cores of the joint portion is in contact with a low refractive index portion having a refractive index lower than that of the second core. The optical multiplexing member in any one.   The optical multiplexing member according to claim 7, wherein the low refractive index portion is an upper cladding layer.   9. The third core according to claim 1, further comprising: a third core that optically connects the two first cores and the second core on the light traveling direction of the two first cores and the second core. The optical multiplexing member according to 1.   The optical multiplexing member according to claim 9, wherein a second gap is provided between the two first cores or / and the second core and the third core.   The light incident on the two first cores is multiplexed by the third core, and the light incident on the two first cores and the light incident on the second core are combined with the joint. The optical multiplexing member according to claim 9 or 10, wherein the optical multiplexing member is multiplexed by the third core.   The width of the connecting portion of the third core that is optically connected to the two first cores and the second core is at least twice the maximum width of the two first cores and the second core. It is 3 times or less, The optical multiplexing member in any one of Claims 9-11.   A light source unit using the optical multiplexing member according to claim 1.   An illumination device using the light source unit according to claim 13.   An image projection apparatus using the light source unit according to claim 13.