JP2015049318A - Optical transmission member and manufacturing method of the same and optical multiplexer, light source unit using these, illumination device, and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission member and a manufacturing method of the same and an optical multiplexer, a light source unit using these, an illumination device, and an image projection device in which a reduction in size can be achieved, and two or more light beams can be multiplexed with low light loss to provide multiplexed light with a uniform intensity distribution of light for each wavelength on the surfaces of cores on an emission part and/or projection image.SOLUTION: There is provided an optical transmission member that includes: a first core 1 and a second core 2 through which light propagate, where the second core 2 has a low refractive index than that of the first core 1; a connection part at which a part of lateral faces substantially parallel to the respective optical axes of the first core 1 and second core 2 start contact with each other; and substantially parallel extension parts 18 in which the first core 1 and second core 2 extend in the substantially one direction from the connection part 16. Also provided are a manufacturing method of the optical transmission member and an optical multiplexer, a light source unit using these, an illumination device, and an image projection device.

Description

  The present invention relates to an optical transmission member, a manufacturing method thereof, an optical multiplexing device, a light source unit using the same, an illumination device, and an image projection device.

Various proposals have been made as a wavelength multiplexing optical multiplexer that combines light of different wavelengths emitted from a plurality of light sources.
For example, in Patent Document 1, a first light is output from a plurality of fiber combined light source units that combine light emitted from a plurality of light sources in a first fiber combiner to form first combined light, using a multimode optical fiber. An invention relating to a combined light source that guides the combined light and further combines in a second fiber combiner to form a 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.
Further, in Patent Document 2, after two or more different wavelengths of light incident from two or more light emitting points adjacent to the surface light emitting element are combined and propagated, the combined light is demultiplexed by a wavelength selection filter. An invention relating to a combined wavelength division multiplexing optical propagation path structure capable of wavelength division multiplexing propagation is disclosed. Patent Document 2 provides an optical propagation technique that can further reduce the cost, the size, and the capacity of an optical propagation path that is used for short-distance light propagation by the wavelength-multiplexed light propagation structure.
The light source described here includes not only light emitting elements such as lasers and LEDs, but also optical fibers and optical transmission members to which these light emitting elements are coupled.

Among such wavelength multiplexing optical multiplexers, for example, they are small and used in a plurality of different types such as those used in endoscopes, small projectors (pico projectors), head mounted displays (eyeglass-shaped image projection devices), and the like. In an illuminating device and an image projection device that combine light of wavelengths and emit white light, there is no uneven intensity distribution of light of each wavelength in the irradiated portion illuminated by the emitted light, and any wavelength of light The distribution shapes are required to be equal.
However, in the combined light source described in Patent Document 1, the uniformity of the intensity distribution of the light is not mentioned, and no means for reducing the size is proposed. In order to make the light intensity distribution uniform with the combined light source of Patent Document 1, the propagation path must be lengthened, and the entire apparatus is enlarged.
Patent Document 2 also mentions light loss, but does not disclose means for making the light intensity distribution uniform.

JP 2007-41342 A JP 2009-199038 A

  The present invention has been made in view of the solution of the above-described problem. At the same time, the two or more lights are combined with low optical loss at the same time, and each wavelength is reduced on the core surface and / or projection image on the emission side. Optical transmission member capable of obtaining combined light with a uniform intensity distribution of light, a method for manufacturing the same, an optical multiplexing device including the optical transmission member, a light source unit using the optical multiplexing device, an illumination device, and An object is to provide an image projection apparatus.

  As a result of intensive studies to solve the above problems, the present inventors have a first core and a second core through which light propagates, and the refractive index of the second core is lower than that of the first core. The first core and the second core have a connection part at which a part of a side surface substantially parallel to at least each optical axis starts to contact, and the first core extends substantially in the same direction from the connection part. And it discovered that the said subject could be solved by setting it as the optical transmission member which has the substantially parallel extension part which a 2nd core extends. The present invention has been completed based on such knowledge.

That is, the present invention
(1) It has the 1st core and 2nd core which light propagates, The refractive index of the 2nd core is lower than the 1st core, and with respect to each optical axis of the 1st core and the 2nd core The optical transmission member has a connection part where a part of the substantially parallel side surfaces starts contact, and a substantially parallel extension part in which the first core and the second core extend from the connection part in substantially the same direction. ,
(2) The optical transmission member according to (1), further including a first cladding layer, the first core and the second core being provided on the first cladding layer,
(3) The optical transmission member according to (1) or (2), wherein side surfaces of the first core and the second core are in contact with each other in the substantially parallel extending portion,
(4) The optical transmission member according to any one of (1) to (3), wherein the second core further covers an upper surface of the first core in the substantially parallel extending portion,
(5) The optical transmission member according to any one of (1) to (4), wherein the first core and the second core have independent portions that extend at least partially with a gap therebetween.
(6) The optical transmission according to any one of (1) to (5), wherein two or more second cores are provided, and one or more second cores start contact from both sides of the first core. Element,
(7) The optical transmission member according to (5) or (6), wherein at least a part of the independent portion of the first core is covered with a second cladding layer on a side surface or / and an upper surface.
(8) In the substantially parallel extending portion, a first taper portion in which a cross-sectional area of the first core in a cross section perpendicular to the extending direction gradually increases from the connection portion toward the substantially parallel extending portion direction. The optical transmission member according to any one of (1) to (7),
(9) The optical transmission member according to (8), wherein the cross-sectional area is enlarged by enlarging a width of the first core as viewed from the upper surface of a cross section perpendicular to the extending direction.
(10) In the substantially parallel extending portion, the ratio (A / B) between the cross-sectional area A of the second core and the cross-sectional area B of the first core in a vertical cross section with respect to the extending direction is The optical transmission member according to any one of (1) to (9), which has a second tapered portion A that gradually decreases toward the substantially parallel extending portion direction,
(11) In the substantially parallel extending portion, a second taper portion B in which a cross-sectional area of the second core having a cross section perpendicular to the extending direction gradually decreases from the connecting portion toward the substantially parallel extending portion. The optical transmission member according to any one of (1) to (10),
(12) In the substantially parallel extending portion, a second taper that gradually reduces the width of the second core viewed from the upper surface of the cross section perpendicular to the extending direction from the connecting portion toward the substantially parallel extending portion. The optical transmission member according to any one of (1) to (11), which includes a portion C and a second tapered portion D that gradually increases the width.
(13) The second core as viewed from above, in which at least a part of at least one of the second taper portion A, the second taper portion B, and the second taper portion C has a cross section perpendicular to the extending direction. The optical transmission member according to any one of (10) to (12), which is a second tapered portion E in which the width of the second core is reduced to reduce the cross-sectional area of the second core,
(14) At least a part of the second taper portion D has a second taper portion F in which the cross-sectional area of the second core is reduced by reducing the width of the second core as viewed from the upper surface of the cross section perpendicular to the extending direction. The optical transmission member according to (12) or (13),
(15) The optical transmission member according to any one of (5) to (14), having a third core on the optical axis of the second core of the independent part,
(16) The multiplexing propagation part is provided in a direction opposite to the connection part of the substantially parallel extending part, and the multiplexing propagation part has a fourth core. Optical transmission member,
(17) The optical transmission member according to any one of (1) to (16), including a light incident portion through which light is incident on each of the first core and the second core.
(18) The light transmission member according to (17), wherein the incident light is light having different wavelengths.
(19) Optical multiplexing having the light transmission member according to any one of (1) to (18) and a light emitting element that emits light from two or more light emitting points to a light incident portion of the light transmission member. apparatus,
(20) The optical multiplexing device according to (19), wherein the light emitting element emits light having specific wavelengths of red, green, and blue from three light emitting points to a light incident portion of the light transmission member,
(21) The optical multiplexing device according to (20), wherein the light emitting element emits the blue light to the first core of the optical transmission member.
(22) A light source unit using the optical multiplexing device according to (20) or (21),
(23) An illumination device using the optical multiplexing device according to (20) or (21),
(24) An image projection device using the optical multiplexing device according to (20) or (21),
(25) The method for manufacturing an optical transmission member according to (1) to (18), wherein the second core and the second cladding layer are patterned simultaneously, the second core and the fourth core. Light having at least one of a step of simultaneously patterning, a step of simultaneously patterning the first core and the third core, and a step of simultaneously patterning the first core and the fourth core Manufacturing method of transmission member,
Is to provide.

  The optical transmission member according to the present invention is miniaturized, and at the same time, combines two or more lights with low optical loss, and the intensity distribution of light of each wavelength is uniform on the core surface and / or projection image on the emission side. It is the optical transmission member which can obtain the combined light which is.

It is sectional drawing which shows the one aspect | mode of the optical transmission member of this invention. It is sectional drawing which shows another aspect of the optical transmission member of this invention. It is sectional drawing which shows another aspect of the optical transmission member of this invention. It is A-A 'sectional drawing of the optical transmission member of this invention. It is B-B 'sectional drawing of the optical transmission member of this invention. It is C-C 'sectional drawing of the optical transmission member of this invention. It is D-D 'sectional drawing of the optical transmission member of this invention. It is E-E 'sectional drawing of the optical transmission member of this invention. It is F-F 'sectional drawing of the optical transmission member of this invention. It is G-G 'sectional drawing of the optical transmission member of this invention. It is the figure which represented typically the propagation pattern of the light from D-D 'to E-E' of the optical transmission member of this invention shown in FIG.1 and FIG.3. It is the figure which represented typically the light propagation mode from D-D 'to F-F' of the optical transmission member of this invention shown in FIG. It is the figure which represented typically the propagation pattern of the light from E-E 'to F-F' of the optical transmission member of this invention shown in FIG.1 and FIG.3.

As shown in FIGS. 1 to 3, the optical transmission member of the present invention has a first core 1 and a second core 2 through which light propagates, and the refractive index of the second core 2 is higher than that of the first core 1. Low and has a connection part 16 where a part of the side surface substantially parallel to the optical axis of each of the first core 1 and the second core 2 (the light propagation axis of the first core 1) starts contact, 16 is an optical transmission member having a substantially parallel extending portion 18 in which the first core 1 and the second core 2 extend in substantially the same direction.
That is, in FIGS. 1 to 3, the connecting portion 16 is a DD ′ cross section, and the substantially parallel extending portion 18 is on the right side of the DD ′ cross section. In each figure, the right side of the FF ′ cross section may be referred to as a combined propagation part.
As a result, the light incident on the second core 2 is converted into the first core 1 having a high refractive index after the connecting portion 16 (including the substantially parallel extending portion 18), or to the first core 1. Propagation through the first core 1 by refraction, interface scattering between the first core 1 and the second core 2, scattering due to stagnation of the refractive index in the first core 1 and / or the second core 2, or the like. Become.
Further, when light is also incident on the first core 1, each light incident on the second core 2 from the connection portion 16 is multiplexed in the first core 1 after the connection portion 16.

  As shown in FIGS. 1 to 3, the light transmission member of the present invention preferably has a light incident portion 19 for receiving light from a light emitting element or the like, and preferably receives light from two or more light emitting points. Moreover, it has the light emission part 20 which radiate | emits the combined light. In addition, the optical transmission member of the present invention may have two or more second cores 2, and one or more second cores 2 may be in contact and connected from both sides of the first core 1. . Thereby, the light from the three or more light incident parts 19 can be multiplexed. For example, to obtain white light by combining visible light rays of red (R), green (G), and blue (B), or to obtain combined light of a desired color by appropriately adjusting their outputs. Can do. When the optical transmission member of the present invention is formed of an organic material, the organic material often has an absorption band in the ultraviolet region, and the transmittance is often lower at a longer wavelength than at a shorter wavelength. For this reason, it is preferable that blue (B) having the longest wavelength is incident from the first core 1 in which light loss due to the structure hardly occurs in a substantially straight optical path. If the light with the lowest transmittance is light of another color, the light may be incident on the first core 1.

  The optical transmission member of the present invention is preferably provided with the first core 1 and the second core 2 on the first cladding layer 5 having a refractive index lower than that of the first core 1 and the second core 2. Thereby, the 1st core 1 and the 2nd core 2 can be connected on a desired position, a desired shape, and the same plane. Moreover, it becomes easy to provide the light incident part 19 and the light emission part 20 in a desired position.

  Moreover, as shown in FIGS. 1-3, it is good for the 1st core 1 and the 2nd core 2 to have the substantially parallel extension part 18 with which at least one part side wall is contacting in the substantially same direction. As a result, a sufficient distance for changing the optical path to the first core 1 can be secured, so that the optical path can be changed efficiently from the second core 2 to the first core 1. From the above viewpoint, as shown in FIGS. 1 and 3, the substantially parallel extending portion 18 is a portion where the side surfaces of the first core 1 and the second core 2 through which light propagates are directly connected without any gap. It is good to have all over.

  As shown in FIG. 8, the second core 2 may further cover the upper surface of the first core. Thereby, the 1st core 1 which is the most main site | parts where light propagates after the connection part 16 can be protected by the 2nd core 2. FIG. In addition, when it is difficult to make the positions of the upper surfaces of the first core 1 and the second core 2 the same (when a step is generated), by covering the upper surface of the first core 1 with the second core 2, The optical axis vertical cross-sectional shape composed of the first core 1 and the second core 2 becomes a substantially rectangular shape, and the light leaking out from the first core 1 and the second core 2 can be reduced.

  The optical transmission member of the present invention further includes an independent portion 17 in which the first core 1 and the second core 2 extend at least partially with a gap (gap or / and the third cladding layer 7) interposed therebetween. It is good to have. Thereby, even when the positions of the plurality of light incident portions 19 are separated, the first core 1 and the second core 2 can be guided to the connection portion 16 using the first core 1 and the second core 2 as optical paths, respectively. Further, by using the independent portion 17, a vertical cross-sectional area with respect to a desired optical axis can be obtained at the connection portion 16 regardless of the position of each light incident portion 19, and a constant light loss can be suppressed. .

  In the independent portion 17, at least a part of the first core 1 may be covered with the second cladding layer 6 on the side surface or / and the upper surface. The second cladding layer 6 is a layer having a refractive index higher than that of the first cladding layer 5 and / or the third cladding layer 7 and lower than that of the first core 1. The difference in refractive index with the surrounding cladding layer can be reduced. As a result, the numerical aperture (NA) of light propagating through the first core 1 can be reduced, and the generation of higher-order modes can be suppressed, so that light propagating through the first core 1 in the independent portion 17 can be reduced. It is possible to suppress leakage to the second core 2 after the connecting portion 16.

  The second cladding layer 6 may be made of the same material as the second core 2 that satisfies the above refractive index condition. Thereby, since it can form from the same material as a 2nd core, the kind of material to be used can be reduced. Further, since it can be manufactured in the same process, the process can be simplified. Further, it is more preferable because high positional accuracy of the second core 2 and the second cladding 6 can be obtained.

  As shown in FIGS. 1 and 2, the optical transmission member of the present invention further includes a third core 3 on the optical axis of the independent part 17 of the second core, and the second core 2 and the third core 3 are It is good to be connected. Thereby, since the light incident part 19 having substantially the same shape as the light incident part 19 provided in the first core can be obtained by using the third core 3, the light of the same condition (same coupling loss, etc.) can be obtained. Incident is possible.

  From the viewpoint of coupling loss in the exchange of good light between the third core 3 and the second core 2, it is preferable that they are in contact with no gap between them, and at least a part of the third core 3 is As shown in FIG. 5, if the side surface and / or the upper surface is covered with the second core 2 made of the same material as the second cladding layer 6, the third core 3 has a larger cross-sectional area than the third core 3. This is because light propagates to the two cores 2 and coupling loss can be further suppressed.

  If the third core 3 is made of the same material as that of the first core 1, the above shape can be easily obtained, and the types of materials used can be reduced. Further, since it can be manufactured in the same process, the process can be simplified. Moreover, since the high positional accuracy of the light-incidence part 19 provided in the 1st core 1 and the 3rd core 3 is obtained, it is more preferable.

  Moreover, in the optical transmission member of the present invention, as shown in FIGS. 1 to 3, a multiplexing propagation part is provided in the direction opposite to the connection part 16 of the substantially parallel extending part 18 (right side from the FF ′ cross section), Among them, the fourth core 4 may be provided on the optical axis of the first core 1. The multiplexing propagation part which has the 4th core 4 is a site | part which propagates the multiplexed light combined, and can draw the light-emitting part 20 in a desired position by drawing a straight line or a curve. Further, since the combined light that is combined tends to have a uniform distribution with distance, providing the fourth core 4 makes it easy to obtain combined light having a uniform distribution.

  If the fourth core 4 is made of the same material as the first core and / or the second core, the type of material used can be reduced. Further, since it can be manufactured in the same process, the process can be simplified. Moreover, since the high position accuracy of the 1st core 1, the 2nd core 2, and the 4th core 4 is acquired, it is more preferable from a viewpoint which can suppress the coupling loss of light.

  As shown in FIGS. 4 to 10, at least one of the first core 1, the second core 2, the third core 3, and the fourth core 4 includes the first core 1, the second core 2, the third core 3, And it is good to be buried in the third cladding layer 7 having a refractive index lower than that of the fourth core 4. Thereby, it becomes possible to protect the embedded first to fourth cores. In addition, for example, when the present optical transmission member is incorporated in a housing or the like, it is preferable because deterioration of light propagation loss due to the influence of an adhesive or a fixing agent can be suppressed. From the above viewpoint, it is preferable that all of the first to fourth cores are embedded in the third cladding layer 7.

In the optical transmission member of the present invention, at least part of the substantially parallel extending portion 18 of the first core 1 has a vertical cross-sectional area with respect to the extending direction gradually from the connecting portion 16 toward the substantially parallel extending portion 18. It is good to have the 1st taper part 8 expanded to. Here, the extending direction is usually the optical axis direction of the first core. Thereby, the vertical cross-sectional area ratio of the 1st core 1 with respect to the 2nd core 2 can be expanded gradually, and the probability that the light which injected into the 2nd core 2 in the independent part 17 will also exist in the 1st core 1 increases. Therefore, it becomes easy to obtain the combined light at least at the emission part. Further, the light incident on the second core 2 by the independent portion 17 is also made substantially parallel by passing through the first taper portion 8 (the angle of the first core 1 with respect to the optical axis 22 is reduced), A part remains in the first core 1 and is combined with the light propagating through the first core 1. Further, since the first core 1 has a higher refractive index than the second core 2, the light incident on the first taper portion 8 from the second core 2 is refracted. For this reason, the frequency | count of reflection of the 2nd core 2 wall surface per unit length can be increased, and the probability that light will remain in the 1st core 1 will rise.
In addition, since the light incident from the first core 1 in the independent portion 17 has a substantially linear propagation, the light loss due to the structure is small.

  As a method of easily providing the first taper portion 8, as shown in the EE ′ to FF ′ sectional views of FIGS. 8 and 9, the first tapered portion 8 is viewed from the upper surface of the vertical section with respect to the extending direction (that is, FIG. The width of the first core is increased (in other words, from the viewpoint of 1 to 3) (in other words, the width in the direction parallel to the first cladding layer 5 and the direction perpendicular to the extending direction of the substantially extending portion 18). And a method of enlarging the cross-sectional area by enlarging.

  Moreover, in the optical transmission member of the present invention, as shown in FIGS. 11 to 13, the second core 2 has a substantially parallel extending portion 18 and a second core cross-sectional area A perpendicular to the extending direction. It is preferable that the ratio (A / B) of the cross-sectional area B of one core has a second tapered portion A10 that gradually decreases from the connecting portion 16 toward the substantially parallel extending portion 18 direction. Thereby, the vertical cross-sectional area ratio of the 1st core 1 with respect to the 2nd core 2 can be expanded gradually, and the probability that the light which injected into the 2nd core 2 in the independent part 17 will also exist in the 1st core 1 increases. Therefore, it becomes easy to obtain the combined light at least at the emission part 20.

  In addition, as shown in FIGS. 11 to 13, in the substantially parallel extending portion 18, the cross-sectional area of the second core perpendicular to the extending direction is gradually increased from the connecting portion 16 toward the substantially parallel extending portion 18. You may have 2nd taper part B11 to reduce. Thereby, the light incident on the second core 2 by the independent portion 17 is collected by the second tapered portion B while reducing the spot diameter (vertical cross section of the first core 1 and the second core 2) to the first core 1. Can shine.

  In addition, the second core 2 of the optical transmission member of the present invention is seen from the upper surface of the cross section perpendicular to the extending direction at the substantially parallel extending portion 18 as shown in FIGS. 1-3, the width of the second core (in other words, the width in the direction parallel to the first cladding layer 5 and the direction perpendicular to the extending direction of the substantially extending portion 18) A second taper portion C12 that gradually decreases from the first taper portion toward the substantially parallel extension portion, and a second taper portion D13 that gradually increases the width on the light emitting portion side from the second taper portion C12. Good. The second tapered portion C12 condenses the light incident on the second core 2 by the independent portion 17 and condenses it on the first core 1, and also exists in the second core 2 at the second tapered portion D13. Light can be made substantially parallel.

Furthermore, as shown in FIGS. 1, 3, and 13, it is better that the first taper portion 8 formed of the first core is covered with the second core and the second taper portion D13. As a result, the second tapered portion D13 can increase the width, reduce the vertical sectional area, and reduce the ratio of the vertical sectional area of the second core 2 to the first core 1. Further, the light that has been made substantially parallel by the second taper portion D13 is incident from the side surface of the first taper portion 8, and at least a part of the light tends to stay in the first core 1 without coming out of the second core 2. Become. Further, as the number of times of reflection at the second taper D13 is increased, the parallel light progresses, and more light remains in the first core 1. In addition, the light that does not stay in the first core 1 but also passes through the first core 1 is converted into a substantially parallel light by refraction, so that the light stays in the first core 1 more efficiently. Further, since the first core 1 has a higher refractive index than the second core 2, the light incident on the first taper portion 8 from the second core 2 is refracted. For this reason, since the number of refractions at the first taper portion 8 and reflection at the second taper portion D13 that contribute to the substantially parallel light per unit length can be increased, the substantially parallel light progresses efficiently. It becomes easy to stay in the first core 1. By staying in the first core 1, the light propagating through the first core 1 and the first core 1 can be combined. Among the above conditions, the second taper portion D13 that reduces at least the vertical cross-sectional area of the second core 2 is a second taper portion F15.
Here, the first tapered portion is formed on both side surfaces of the first core as seen from the upper surface (that is, the viewpoint of FIGS. 1, 3, and 13), as shown in FIGS. This means a taper shape, and the second taper portion is the second core viewed from the top surface (that is, the viewpoint of each figure), as shown in FIG. 1, FIG. 2, FIG. 3, FIG. It means a tapered shape formed on both sides of the whole (that is, when there are two second cores as shown in each figure, the whole of them together).

At least a part of at least one of the second taper part A10, the second taper part B11, and the second taper part C12 has a width (in other words, the width of the second core as viewed from the top surface in a cross section perpendicular to the extending direction. For example, the width in the direction parallel to the first cladding layer surface and the direction perpendicular to the extending direction of the substantially parallel extending portion) is gradually reduced from the connecting portion 16 toward the substantially parallel extending portion direction to reduce the cross-sectional area. The second tapered portion E14 is preferable. Further, at least a part of the second taper portion D is formed by gradually reducing the width of the second core viewed from the upper surface of the cross section perpendicular to the extending direction from the connecting portion 16 toward the substantially parallel extending portion direction. It is preferable that the second taper portion F15 has a small cross-sectional area of the second core. By doing so, a taper can be easily provided.
Hereinafter, each member used for the optical transmission member of the present invention will be described in detail.

[First core]
The first core 1 used in the optical transmission member of the present invention is one of light propagation paths through which light propagates. From the second core 2, the first cladding layer 5, the second cladding layer 6, and the third cladding layer 7. In addition, the refractive index is high, and it should have transparency that does not cause a problem in optical transmission with respect to the wavelength of propagating light.
The refractive index difference between the first core 1 and the second core 2, the first cladding layer 5, the second cladding layer 6, or the third cladding layer 7 is the refractive index difference represented by the following formula (1): 0.1 to 6.0% (a value obtained by multiplying the following formula by 100), and from the viewpoint of light confinement and ease of controlling the refractive index of the material, 1.0 to 6.0%. It is better if it is, and it is even better if it is 2.0 to 6.0%.
(Refractive index difference) = (n ₁ ² −n ₂ ² ) ^1/2 / (2 × n ₁ ² ) (1)
* High refractive index layer refractive index: n ₁ , Low refractive index layer refractive index: n ₂

[First core material and forming process]
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. In the case of quartz or glass, a fiber-like one can also be used, and an optical fiber core wire (portion where light propagates) is preferably used. From the viewpoint of workability to an arbitrary position and shape, a resin film It is more preferable that it is a material that can be processed by photolithography, intaglio formation, and injection molding. In addition, from the viewpoint of arranging a portion other than the first core 1 (for example, the second cladding layer 6 and the second core 2) in a three-dimensional manner, using a photolithography process can provide a higher positional accuracy with respect to the other portions. . As a photolithography processing method, a first core-forming resin varnish or a first core-forming resin film is applied on the first cladding layer 1 and laminated by pressing, laminating, pressing, or the like, and then a first layer formed in advance. A pattern forming resist is disposed on the core 1 forming resin layer, the first core 1 is processed into a desired shape by RIE (Reactive Ion Etching) or the like, and then the pattern forming resist is removed. A photosensitive resin composition for forming the first core 1 is laminated on the first cladding layer 5 in the same manner as described above, and then irradiated with actinic rays or actinic rays through a film mask or glass mask on which a desired shape is drawn. The pattern can be formed by directly drawing in a desired shape with the beam light and removing the uncured resin composition for forming the first core 1 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 resin composition for forming the first core 1 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.

[Shape of the first core]
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 means not a branching path or a divided optical path but a series of optical paths. Thereby, the optical loss resulting from the structure of the light propagating through the first core 1 can be reduced. If the width of the first core 1 in the direction perpendicular to the optical axis from the plan view direction is 8 μm to 1.0 mm, low-loss propagation is possible, and light from the second core 2 is efficiently transmitted to the first core 1. From the standpoint of staying, it is more preferably 20 μm to 500 μm, and from the viewpoint of reducing the spot diameter of the light emitting portion 20 and obtaining a good coupling loss with the light receiving element, it is further preferably 20 μm to 200 μm.
If the height from the surface of the first cladding layer 5 of the first core 1 is low, a good coupling loss between the light emitting part 20 and the light receiving element is obtained, and if it is large, a good coupling between the light incident part 19 and the light emitting element is obtained. Loss is obtained. From the above viewpoint, the height of the first core 1 is preferably 8 μm to 1.0 mm, and from the viewpoint of workability, it is preferably 20 μm to 500 μm. From the viewpoint of workability in photolithography, and the first used for it. From the viewpoint of the film formability of the resin for forming 1 core 1, the thickness is further preferably 20 μm to 150 μm.

[First taper part]
Further, the first core 1 may be provided with a first taper portion 8 in which the vertical cross-sectional area in the extending direction (that is, the optical axis direction of the first core) gradually increases at the substantially parallel extending portion 18. The angle formed by the optical axis 22 of the first taper portion 8 is preferably 0.1 to 45 °, and the light propagating through the first core 1 and the light remaining on the first core 1 from the second core 2 are substantially omitted. From the viewpoint of securing a sufficient distance for collimation, it is better to be 0.1 to 10 °, and from the viewpoint of reducing the spot diameter at the light emitting portion 20, 0.1 to 3 °. Even better. The length of the first taper portion 8 in the direction of the optical axis 22 is not particularly limited as long as it does not hinder the propagation of light, but is preferably 0.2 mm to 500 mm. From 2 mm to 20 mm, it is better, and from the viewpoint of reducing light loss due to the transmittance of the material, it is more preferably 0.2 mm to 10 mm.

[Second core]
The second core 2 is disposed in the independent portion 17 with a gap from the first core 1, is directly connected to the first core 1 at the connection portion 16, and is substantially parallel to the optical axis 22 at the parallel extension portion 18. This is one of the light propagation portions having a refractive index lower than that of the first core 1 extending in a substantially parallel direction. The number of the second cores connected to the first core 1 by the connecting portion 16 may be one or more, may be two as shown in FIGS. 1 to 3, or may be more. By directly contacting the first core 1, light can be efficiently exchanged between the first core 1 and the second core 2. Here, the substantially parallel direction means that the angle of the surface where the optical axis 22 of the first core 1 is in contact with the second core 2 and the first core 1 is not less than 0 ° and not more than 22.5 °. Similarly to the first core 1, the second core 2 may have transparency enough to cause no problem in optical transmission with respect to the wavelength of light propagating.
The refractive index difference between the second core 2 and the first cladding layer 5 and between the second core 2 and the third cladding layer 7 is 0.1 to 6.0% in refractive index difference represented by the above formula (1) From the viewpoint of light confinement and the ease of controlling the refractive index of the material, it is preferably 1.0 to 6.0%, and more preferably 2.0 to 6.0%. .
The material of the second core 2 can be the same material as that of the first core 1 described above.
The formation method of the 2nd core 2 can be performed by the method similar to the 1st core 1 mentioned above.

[Second core shape (independent part)]
The shape of the second core 2 from the upper surface (that is, the plan view direction) is preferably a substantially straight line and / or a substantially curved line in the independent portion 17. The above-mentioned substantially straight line / substantially curved line means not a branching path or a divided optical path but a series of optical paths. Thereby, the optical loss resulting from the structure of the light incident on the second core 2 can be reduced. When the width in the vertical direction with respect to the optical axis from the planar view direction of the second core 2 in the independent portion 17 is 8 μm to 1.0 mm, low-loss propagation is possible, and the vertical direction with respect to the optical axis 22 in the connection portion 16 From the viewpoint of obtaining a low loss by reducing the width of the film, it is more preferably 20 μm to 500 μm, and further preferably 20 μm to 200 μm.
If the height of the second core 2 from the surface of the first cladding layer 5 is small, a good coupling loss between the light emitting part 20 and the light receiving element is obtained, and if it is large, a good coupling between the light incident part 19 and the light emitting element is obtained. Loss is obtained. Further, when the height is about the same as that of the first core 1, the second core 2 can efficiently propagate to the first core 1. From the above viewpoint, the height of the first core 1 is preferably 8 μm to 1.0 mm, and from the viewpoint of workability, it is preferably 20 μm to 500 μm. From the viewpoint of workability in photolithography, and the first used for it. From the viewpoint of the film formability of the resin for forming 1 core 1, the thickness is further preferably 20 μm to 150 μm. The difference in height from the first core 1 is 0 μm to 50 μm, more preferably 0 μm to 30 μm, and still more preferably 0 μm to 15 μm.

[Second core shape (connection part)]
The angle between the optical axis of the light propagating through the second core 2 at the connection portion 16 of the second core 2 and the optical axis 22 of the first core 1 is not particularly limited, but is 0 ° to 45 °. From the viewpoint of reducing loss, it is preferably 0 ° or more and 25 °, and more preferably 0 ° or more and 15 °. Usually it is greater than 0 ° C. When it is desired to reduce reflection on the side surface of the second core 2, the angle formed with the optical axis 22 of the first core 1 is the center of the first core 1 of EE ′ in FIGS. The angle between the straight line connecting the centers of the second cores 2 and the optical axis 22 is preferably ± 5 °.

[Shape of second core (substantially parallel extending portion)]
The shape of the second core 2 from the upper surface (that is, in plan view) at the substantially parallel extending portion 18 is at least partly in contact with at least part of the side surface substantially parallel to the first core 1 and the optical axis 22. The structure is not particularly limited as long as it is parallel to the contacting surface, or has a taper that expands toward the light emitting portion 19 even if it has a taper that decreases toward the light emitting portion 19. Or they may be mixed.

[Second taper part]
As shown in FIG. 2, in the case where uniform light is obtained by the light emitting portion 19, the cross-sectional area is set so that one of the above-described tapered portions A10, B11, and C12 is satisfied (in the drawing, both conditions are satisfied). When a tapered portion whose width viewed from the upper surface is reduced is provided, the light incident from the second core 2 is reflected on the wall surface of the second core 2 at the substantially parallel extending portion 18 and the spot diameter gradually decreases. At the same time, since the area occupied by the first core 1 with respect to the total area of the first core 1 and the second core 2 is increased, uniform light can be easily obtained. Since the optical transmission member of the present invention has the first core 1, the number of reflections per unit length increases compared to the case without the first core 1, and uniform light can be obtained at a shorter distance. it can. The angle (gradient) formed by the first taper portion 8 with respect to the optical axis 22 at this time is preferably 0.1 ° to 45 °, and preferably 0.1 ° to 25 ° from the viewpoint of reducing loss. More preferably, the angle is 0.1 ° to 15 °. The lengths of the taper portions B11, C12, and E14 are not particularly limited as long as they do not hinder the propagation of light, but are preferably 0.2 mm to 500 mm, and from the viewpoint of miniaturization, 0.2 mm to 20 mm. It is more preferable that the thickness is 0.2 mm to 10 mm from the viewpoint of reducing light loss due to the transmittance of the material.
As shown in FIGS. 1 and 3, when it is desired to obtain not only uniform light at the light emitting portion 20 but also uniform light in the projected image, the above-described tapered portion E14 (any condition in the figure). If a taper that expands is provided, as in any one of the taper portions D13 and F15 (same conditions in the drawing) after the taper portions A10, B11, and C12), The light incident from the two cores 2 is reflected on the wall surface of the second core 2 at the substantially parallel extending portion 18, and the angle formed with the optical axis 22 gradually decreases, so that the sum of the first core 1 and the second core 2 is increased. Since the area occupied by the first core 1 with respect to the area is increased, uniform light can be easily obtained. At this time, the angle of the taper with respect to the optical axis 22 is preferably 0.1 ° to 45 °, and is preferably 0.1 ° to 25 ° from the viewpoint of reducing the loss, and more preferably, the angle is 0.1. It may be 1 ° to 15 °. The lengths of the taper portions D13 and F15 are not particularly limited as long as they do not hinder the propagation of light, but are preferably 0.2 mm to 500 mm, and are 0.2 mm to 20 mm from the viewpoint of miniaturization. More preferably, it is more preferably 0.2 mm to 10 mm from the viewpoint of reducing light loss due to the transmittance of the material.
It is further preferable that the first taper portion 8 is provided on the first core 1 at this location. Thereby, the angle formed with the optical axis 22 of the light emitted from the first core 1 side surface to the second core 2 is larger than the angle formed with the optical axis 22 of the light incident on the first core 1 from the second core 2 side surface. Is smaller. That is, when it passes through the first core 1, it becomes a substantially parallel light. Furthermore, the light reflected by the side surface of the second core 2 (the outside or the interface with the third cladding layer 7) is gradually converted into substantially parallel light. By repeating these, a light component that satisfies the total reflection conditions of the first core 1 and the second core 2 appears, and further, since refraction and reflection are repeated, many light components are likely to stay in the first core 1. Become. At this time, if the angle of the taper portion D13 with respect to the optical axis 22 is equal to or smaller than the angle of the first taper 8 provided on the first core 1 with respect to the optical axis 22, This is more preferable because the area ratio of the first core 1 to the total cross-sectional area of the second core 2 can be increased efficiently.

[Third core]
The third core 3 used in the optical transmission member of the present invention is one of light propagation paths through which light propagates, and has a higher refractive index than the first cladding layer 5, the second cladding layer 6, and the third cladding layer 7. It should be transparent enough to cause no problem in optical transmission with respect to the wavelength of the propagating light.
The refractive index difference between the third core 3 and the first cladding layer 5, the second cladding layer 6, or the third cladding layer 7 is 0.1 to 6. 0%, preferably from 1.0% to 6.0%, and from 2.0% to 6.0% from the viewpoint of light confinement and ease of controlling the refractive index of the material. Even better.
The material of the third core 3 can be the same material as the first core 1 described above.
The third core 3 can be formed by the same method as the first core 1 described above.
When the third core 3 is formed of the same material as that of the first core 1, it is easy to ensure the above refractive index difference, and the number of materials can be reduced. In addition, it is more preferable to form the third core in the same process as the first core 1 because high positional accuracy between the first core 1 and the third core 3 can be easily obtained.

[Third core shape]
As shown in FIGS. 1 and 2, the shape of the third core 3 in plan view is a shape connected to the second core 2 on the optical axis of the independent portion 17 of the second core 2, or at least the third core 3. It is preferable that a part of the shape is embedded in the second core 2. Thereby, since the light incident part 19 having substantially the same shape as the light incident part 19 provided in the first core can be obtained by using the third core 3, the light of the same condition (same coupling loss, etc.) can be obtained. Incident is possible. From the viewpoint of coupling loss in good light transmission and reception between the third core 3 and the second core 3, it is preferable that they are connected without a gap between them, and at least a part of the third core 3 is When the side surface or / and the upper surface are covered with the second core 2, light propagates from the third core to the second core 2 having a larger cross-sectional area than the third core 3, and the coupling loss can be further suppressed. Good. From the above viewpoint, the width (width in the direction perpendicular to the optical axis propagating through the second core 2) viewed from the upper surface (plan view) of the third core 3 is preferably equal to or smaller than the width of the second core 2. It is good if it is less than the width of the two cores 2. More preferably, the width is the same as that of the light incident portion 19 of the first core 1. Moreover, when the second core 2 covers the third core 3, the second core 2 can function as a clad. From the above viewpoint, the entire area of the third core 3 may be covered with the second core 2. As a result, the appearance of high-order mode light can be suppressed, and multiplexing after the connecting portion 16 can be performed with low loss.
The height of the 3rd core 3 is the same height as the cross section of the 2nd core 2, or the height included, Comprising: It is good in it being 8 micrometers-1.0 mm, and it is 20 micrometers-500 micrometers from a viewpoint of workability. In addition, from the viewpoint of workability in photolithography and the film formability of the third core 3 forming resin used therefor, the thickness is further preferably 20 μm to 150 μm. The difference in height from the second core 2 is from 0 μm to 50 μm, more preferably from 0 μm to 30 μm, and even more preferably from 0 μm to 15 μm.
Further, as shown in FIGS. 1 to 3, the third core may have a boundary with the second core 2 on the light incident part 19 side than the connection part 16, and the light emitting part 20 rather than the connection part 16. There may be a boundary with the second core 2 on the side.

[Fourth core]
The fourth core 4 used in the optical transmission member of the present invention is one of the light propagation paths through which light propagates. The fourth core 4 has a higher refractive index than the first cladding layer 5 and the third cladding layer 7, and the wavelength of the propagating light. On the other hand, it should be transparent so that there is no problem in optical transmission.
The refractive index difference between the fourth core 4 and the first cladding layer 5 and the third cladding layer 7 is such that the refractive index difference represented by the above formula (1) is 0.1 to 6.0%. From the viewpoint of light confinement and the ease of controlling the refractive index of the material, it is preferably 1.0 to 6.0%, and more preferably 2.0 to 6.0%.
Moreover, if the 4th core 4 consists of the same material as the said 1st core or / and a 2nd core, the kind of material to be used can be reduced. Further, since it can be manufactured in the same process, the process can be simplified. Moreover, since the high position accuracy of the 1st core 1, the 2nd core 2, and the 4th core 4 is acquired, it is more preferable from a viewpoint which can suppress the coupling loss of light.

[Fourth core position and shape]
The fourth core 4 preferably has a multiplexing propagation part in a direction opposite to the connection part of the substantially parallel extending part, and is preferably located in the multiplexing propagation part. Moreover, the shape from the upper surface (plan view) of the fourth core 4 is a straight line parallel to the optical axis direction at least in the vicinity of the light emitting portion 19 as shown in FIGS. Is preferred. In order to form the light emitting portion 19 if it is a straight line, for example, when smoothing with a dicing saw, laser, polishing, etc., the light emitting portion 19 having the same shape is obtained even if the processing position is slightly shifted. Can do. From the above viewpoint, the length of the fourth core 4 in the direction of the optical axis 22 may be 0.01 μm or more, and is preferably 500 mm or less from the viewpoint that it is easy to obtain combined light with a uniform distribution. From the viewpoint of downsizing, it is preferably 0.01 μm or more and 10 mm or less, and more preferably 0.01 μm or more and 5 mm or less.
Further, the lower limit of the width of the fourth core 4 in the direction perpendicular to the optical axis 22 may be equal to or larger than the width of the first core 1 connected to the fourth core 4, and the second lower limit connected to the fourth core 4 is also the same. It is good if it is more than the width of the core 2. The upper limit of the width is preferably 2 mm or less, more preferably 1 mm or less, and further preferably 500 μm or less from the viewpoint of coupling loss with the light receiving element.

[First cladding layer]
The first cladding layer 5 provided below the first core 1 and the second core 2 used in the optical transmission member of the present invention has a refractive index higher than that of the first core 1 and the second core 2 as described above. Low is preferable because light can propagate while repeating total reflection at the interface between the core and the first cladding layer 5. If the above conditions are satisfied, the material of the first cladding layer 5 is not particularly limited, and quartz, glass, resin, or the like is used.

[Method for Forming First Cladding Layer]
Among these, a resin is preferable from the viewpoint of workability. As a method for forming the first cladding layer 5, for example, a varnish-like cladding layer forming resin is applied, or a film-like cladding layer forming resin is laminated or pressed. Etc., and a method of laminating on the subject to form the first cladding layer 5. From the viewpoint of curing after application or lamination, a thermosetting resin, a photocurable resin, or a combined photo / thermal curable resin is preferable.

[Thickness of the first cladding layer]
When the resin is used, the thickness of the first cladding layer 5 is not particularly limited, but is preferably 5 μm or more from the viewpoint of the light confinement property of the first core and the second core, and a thick resin layer can be formed. In view of the above, the thickness is preferably 200 μm or less. The thickness is more preferably 10 μm or more and 100 μm or less from the viewpoint of thickness control, and further preferably 10 μm or more and 50 μm or less from the viewpoint of low profile.
The first cladding layer 5 may be a single layer or a plurality of layers, and at least one of them may be patterned. Further, it may be the same material as the third cladding layer 7 described later or a different material.
Moreover, when the 1st clad layer 5 consists of plate-shaped quartz and glass, it is good in the range of 40 micrometers-10 mm.

[Second cladding layer]
In the independent portion 17, at least a part of the first core 1 may be covered with the second cladding layer 6 on the side surface or / and the upper surface. As described above, the second cladding layer 6 is preferably a layer having a refractive index higher than that of the first cladding layer 5 and / or the third cladding layer and lower than that of the first core 1. Moreover, since it is necessary to pattern, it is good to use the patternable material similar to the 2nd core 2 mentioned above.
Further, when the second clad layer 6 is made of the same material as that of the second core, the above conditions can be satisfied and the types of materials to be used can be reduced. In addition, since the second core 2 and the second cladding layer 6 can be manufactured in the same process, the process can be simplified. Further, high positional accuracy between the second core 2 and the second cladding layer 6 can be obtained.

[Shape of the second cladding layer]
Further, the lower limit of the width in the direction perpendicular to the optical axis 22 of the second cladding layer 6 is preferably 5 μm or more wider than one side surface of the first core 1 (10 μm on both sides) because the light confinement property is improved, and further 10 μm The above is more preferable because the side surface of the first core 1 can be covered even if the formation position is slightly deviated. The upper limit of the width is not particularly limited, but it is sufficient that the second core 2 and the connection portion 16 are not connected on the light incident portion 19 side.

[Third cladding layer]
The first cladding 1, the second core 2, the third core 3, and the fourth core 4 used for the optical transmission member of the present invention are embedded, and the third cladding layer 7 for protecting them is as described above. If the refractive index is lower than those of the first core 1, the second core 2, the third core 3, and the fourth core 4, light can propagate while repeating total reflection at the interface between the core and the first cladding layer 5. Therefore, it is preferable.

[Method for Forming Third Clad Layer]
The material of the third cladding layer 7 is not particularly limited, and the same material as that of the first cladding layer 5 described above can be used as long as the material can embed the first core 1 and the second core 2.
Although there is no limitation in particular as a formation method of the 1st cladding layer 5, the method similar to the 1st cladding layer 5 mentioned above can be used.

{Thickness of the third cladding layer}
The thickness of the third cladding layer 3 is not particularly limited, but is a thickness capable of embedding the first core 1 and the second core 2, and there is no particular problem as long as light can be confined in those cores. 0.0 mm, preferably from 20 μm to 550 μm, from the viewpoint of workability, from the viewpoint of workability in photolithography, and from the viewpoint of film formation of the first core 1 forming resin used therefor, from 20 μm to More preferably, it is 200 μm.
The first clad layer 5 may be a single layer or a plurality of layers, and at least one of them may be patterned. Moreover, the same material as the first cladding layer 5 described above or a different material may be used.

[substrate]
By having the substrate 21 (see FIGS. 4 to 10), the optical transmission member of the present invention has an effect of imparting toughness, rigidity, and flexibility to the optical transmission member. When the substrate 21 is not necessary, it may be peeled off from the first cladding layer in a later step (at least after the first cladding layer 1 is formed).
From the above viewpoint, the material of the substrate 21 that can be used for the optical transmission 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. In the case where the refractive index is lower than that of the first core 1 and the second core 2 and the substrate 21 is transparent enough to prevent the propagation of light propagating through the first core 1 and the second core 2, the substrate 21 is used as the first cladding layer. It may be 5.
In addition, when the substrate 21 and the first cladding layer 1 are separate, and they are not adhesive or weak, a substrate with an adhesive layer in which an adhesive layer is provided on the surface of the substrate 21 may be used. You may use the board | substrate which gave the roughening process or the coupling process to the surface of the board | substrate 21. FIG.

[Rigid board]
When it is desired to impart rigidity to the optical transmission member, it is preferable to use a rigid and tough substrate 21 as the substrate 21, such as a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate, Preferred 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 21 at this time is not particularly limited, but if it is 40 μm or more, there is an advantage that the strength as the substrate 21 is easily obtained, and if it is 10000 μm or less, a rigid and low-profile optical transmission member is obtained. There is an advantage that it is easy. From the above viewpoint, the thickness of the substrate 21 is more preferably in the range of 50 to 1000 μm.

[Flexible substrate]
When it is desired to impart flexibility to the optical transmission member, it is preferable to use a flexible and tough substrate 21 as the substrate 21, 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 21 at this time is not particularly limited, but if it is 5 μm or more, there is an advantage that the strength as the substrate 21 is easily obtained, and if it is 200 μm or less, the advantage is that it is easy to obtain flexibility with a low profile. There is. From the above viewpoint, the thickness of the substrate 21 is more preferably in the range of 10 to 100 μm.

  The manufacturing method of the optical transmission member of the present invention is not particularly limited, and may be manufactured according to the manufacturing method of a general-purpose optical waveguide, and the second core and the second cladding layer are patterned simultaneously. Patterning the second core and the fourth core simultaneously, patterning the first core and the third core simultaneously, and patterning the first core and the fourth core simultaneously. It is preferable to have at least one of the steps to be performed.

[Light emitting element]
In the present invention, it is preferable to provide a light incident portion 19 through which light is incident on each of the first core 1 and the second core 2 of the independent portion 17. The light incident part 19 is provided in the first core 1, the second core 2, and the third core 3 of the independent part 17. Thereby, the light incident thereon propagates in the direction of the connecting portion 16, and the respective lights are combined at the substantially parallel extending portion 18.
In the present invention, a member that makes light incident on the light incident portion 19 is called 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. Examples thereof include an optical fiber and an optical waveguide. Further, a lens or the like may be appropriately used between the light emitting elements and the light incident portion 19.
The light used may have different wavelengths or the same wavelength, and examples thereof include infrared light, visible light, and ultraviolet light. If the wavelength is the same, the amount of light output from the optical transmission member can be increased, and if the wavelengths are different, combined light is obtained. When the incident light is visible light, for example, if blue light of 380 to 495 nm, green light of 495 to 570 nm, and red light of 620 to 750 nm are respectively incident, white light is emitted and output thereof The hue can be arbitrarily selected depending on the difference.

[Light receiving element]
A light emitting portion 20 is provided in the opposite direction to the connection portion 16 of the substantially parallel extending portion 18 of the present invention, and the combined light is output from the light emitting portion 20 to the outside of the optical transmission member. In the present invention, a member that receives light provided at the tip of the light emitting portion 20 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 20.
When the optical fiber is used as the light emitting element or 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 Gated-Index type. The core diameter of the optical fiber is not particularly limited, but the diameter is preferably 10 μm to 1000 μm, more preferably 30 μm to 200 μm, and even more preferably 50 μm to 150 μm. 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.

The optical multiplexing device of the present invention includes the light transmission member and a light emitting element that emits light from two or more light emitting points to the light incident portion 19 of the light transmission member.
Preferably, the light emitting element emits light having specific wavelengths from three light emitting points of red, green, and blue to the light incident portion 19 of the light transmission member, and the light emitting element is the light transmission member of the light transmission member. More preferably, the blue light is emitted to the first core 1.
The optical multiplexing device of the present invention can be applied to a light source unit, an illumination device, and an image projection device.

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 films for forming first and third cladding layers>
[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 in 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. . 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, and further stirring at 95 ° C. for 1 hour. A) A (meth) acrylic polymer solution (solid content: 45% by mass) was obtained.

[Measurement of weight average molecular weight]
(A) The result of having measured the weight average molecular weight (standard polystyrene conversion) of (meth) acrylic polymer using GPC ("SD-8022", "DP-8020", and "RI-8020" by Tosoh Corp.). 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 first and third cladding layers]
As a base polymer, 84 parts by mass (solid content 38 parts by mass) of the (A) (meth) acrylic polymer solution (solid content 45% by mass), (B) urethane (meth) acrylate having a polyester skeleton as a photocuring component ( Shin-Nakamura Chemical Co., Ltd. “U-200AX”) 33 parts by mass, and urethane (meth) acrylate having a polypropylene glycol skeleton (Shin-Nakamura Chemical Co., Ltd. “UA-4200”) 15 parts by mass, (C ) As a thermosetting component, a polyfunctional block isocyanate solution (solid content 75% by mass) obtained by protecting isocyanurate type trimer of hexamethylene diisocyanate with methyl ethyl ketone oxime (“Sumijour BL3175” manufactured by Sumika Bayer Urethane Co., Ltd.) 20 1 part by mass (solid content 15 parts by mass), (D) 1- [4- 2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (“Irgacure 2959” manufactured by BASF Japan Ltd.), 1 part by weight, 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 for forming a cladding layer.

[Preparation of resin films for forming first and third cladding layers]
The first and third clad layer forming resin varnishes obtained above are 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. (Multicoater TM-MC, manufactured by Hirano Techseed Co., Ltd.), dried at 100 ° C. for 20 minutes, and then subjected to surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd.), A thickness of 25 μm) was pasted to obtain resin films for forming the first and third cladding layers.
At this time, the thickness of the resin layer formed from the first and third clad layer forming resin varnishes can be arbitrarily adjusted by adjusting the gap of the coating machine, and the thickness after drying will be described later. .

[Measurement of refractive index]
The 50 μm 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). 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. Next, ultraviolet rays (wavelength 365 nm) were irradiated with 2000 mJ / cm ² with the 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 (manufactured by Metricon, trade name: Model 2020).

<Preparation of Resin Film for Forming First Core, Third Core, and Fourth Core>
(A) As a base polymer, 26 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Toto Kasei Co., Ltd.), and (B) 9,9-bis [4- (2- Acrylyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and bisphenol A type epoxy acrylate (trade name: EA-1020, Shin-Nakamura Chemical Co., Ltd.) ) 36 parts by mass, (C) As a photopolymerization initiator, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Ltd.), and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (trade name: Irgacure 2959, ASF Japan Co., Ltd.) 1 part by weight, core layer-forming resin in the same manner and conditions as the above-mentioned preparation of the clad layer-forming resin varnish except that 40 parts by weight of propylene glycol monomethyl ether acetate was used as the organic solvent A varnish was prepared. Thereafter, pressure filtration and degassing under reduced pressure were performed in the same manner and conditions as described above.
On the non-treated surface of the PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm), which is a support film, the core layer-forming resin varnish obtained above and After applying and drying in the same manner, a release PET film (trade name: PUREX A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) is attached as a protective film so that the release surface is on the resin side. A resin film for forming a core layer was obtained.
At this time, the thickness of the resin layer formed from the resin varnish for forming the core layer can be arbitrarily adjusted by adjusting the gap of the coating machine, and the 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 for Forming Second Core and Second Cladding Layer>
[Second Core, Second Polymer for Forming Cladding Layer; Production of (Meth) Acrylic Polymer (P-1)]
In a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, 42 parts by mass of propylene glycol monomethyl ether acetate and 21 parts by mass of methyl lactate were weighed and stirred while introducing nitrogen gas. . 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, and further continued stirring at 95 ° C. for 1 hour to obtain a (meth) acrylic polymer (P-1) solution (solid content: 45 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 and second cladding layer]
(A) As an alkali-soluble (meth) acrylic polymer containing a maleimide skeleton in the main chain, 60 parts by mass of the P-1 solution (solid content 45% by mass), (B) as a polymerizable compound, ethoxylated bisphenol A diacrylate ( Hitachi Chemical Co., Ltd., trade name: FANCLIL FA-324A ("FANCLIL" is a registered trademark)) 15 parts by mass and ethoxylated bisphenol A diacrylate (Hitachi Chemical Co., Ltd., trade name: FANCLIL FA- 321A) 15 parts by mass, phenol biphenylene type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: NC-3000, epoxy equivalent 275 g / eq) 10 parts by mass, (C) 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (manufactured by BASF Japan Ltd.) Product name: Irgacure 2959) 1 part by weight, 1 part by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by BASF Japan Ltd., trade name: Irgacure 819) was weighed in a wide-mouthed plastic bottle, Using a stirrer, the core part-forming resin varnish was prepared by stirring for 6 hours under the conditions of a temperature of 25 ° C. and a rotation speed of 400 min ⁻¹ . Thereafter, using a polyflon filter having a pore size of 2 μm (product name: PF020, manufactured by Toyo Roshi Kaisha, Ltd.) and a membrane filter having a pore size of 0.5 μm (product name: J050A, manufactured by Toyo Roshi Kaisha, Ltd.), a temperature of 25 ° C., Pressure filtration was performed under the condition of a pressure of 0.4 MPa. Subsequently, vacuum degassing was performed for 15 minutes using a vacuum pump and a bell jar under the condition of a reduced pressure of 50 mmHg to obtain a resin varnish for forming a second core and a second cladding layer.

[Production of Resin Film for Forming Second Core and Second Cladding Layer]
The second core and the second clad layer forming resin varnish are coated on a non-treated surface of a PET film (manufactured by Toyobo Co., Ltd., trade name: A1517, thickness 16 μm) with a multi coater made by Hirano Techseed Co., Ltd. , Trade name: TM-MC), dried at 100 ° C. for 20 minutes, and then a release PET film (manufactured by Teijin DuPont Films, trade name: Purex A31, thickness 25 μm) as a protective film. A resin film for forming a second core and a second cladding layer was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine, and the 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 1.555.

<Example of production of optical transmission member in FIG. 1>
[Formation of the first cladding layer]
Using a 100 mm × 100 mm polyimide film (polyimide: manufactured by Toray DuPont Co., Ltd., Kapton EN, thickness: 25 μm) as the substrate 1, for forming the first cladding layer of 15 μm thickness obtained above on one surface After peeling off the protective film of the resin film, after vacuuming to 500 Pa or less using a vacuum pressurization type laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.), pressure 0.4 MPa, temperature 90 ° C., pressurization time Lamination was performed by thermocompression bonding under conditions of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm ² from the support film side of the first clad layer forming resin film 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 first cladding layer 1 was formed.

[Formation of first core, third core, and fourth core]
Next, the first core-forming resin film having a thickness of 60 μm obtained above is peeled off from the surface on which the first clad layer 5 is formed, and then the roll laminator (Hitachi Chemical Technoplant Co., Ltd.) is peeled off. Manufactured by HLM-1500) under the conditions of pressure 0.4 MPa, temperature 50 ° C., laminating speed 0.2 m / min, and then the above-mentioned vacuum pressure laminator (manufactured by Meiki Seisakusho, MVLP-500) After vacuuming to 500 Pa or less, 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, the length of the independent portion 17 in the optical axis direction is 3.0 mm, the distance from DD ′ to EE ′ of the connecting portion 16 is 1.5 mm, and from EE ′ to FF ′. The first core 1 that has a distance of 3.0 mm and a width that gradually increases from 40 μm to 90 μm from the light incident part 19 to EE ′, 40 μm from the EE ′ to FF ′, and the light incident part 30 The length is 0.2 mm, the width is 40 μm, and the distance from the light incident portion 19 of the first core 1 is 125 μm, the two third cores 3 and the FF ′ to the light emitting portion 20. A negative photomask having an opening that can be formed to be a part of the fourth core 4 having a distance of 0.5 μm and a width from FF ′ to the light emitting portion 20 of 90 μm, the first core, Using the above-described ultraviolet exposure machine, the ultraviolet rays (wavelength 365 nm) are reduced to 0 from the support film side of the resin films for forming the third core and the fourth core. Irradiated at 8 J / cm ^2, then subjected to 5 minutes after exposure heated at 80 ° C.. 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 formed the 1st core 1, the 3rd core 3, and the 4th core 4 part, respectively. The thickness of a part of the obtained first core 1, third core 3, and fourth core 4 on the first cladding layer 1 was 60 μm.

[Formation of second core and second cladding layer]
After peeling off the protective film of the 65 μm-thick second core and the second clad layer forming resin film obtained above on the first core 1 formation surface obtained above, a vacuum pressure laminator (name of Co., Ltd.) After evacuating to 500 Pa or less using MVLP-500 (manufactured by Kikai Seisakusho), it 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, the length in the direction of the independent portion 17 from the connecting portion 16 is 2.9 mm (the connecting portion 16 and the third core 3 are connected) using an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). In this way, an S-shaped curve is drawn, one side is connected to the third core 3, and the connection portion 16 has a shape such that the distance from the center of the first core 1 to the center of the second core is 75 μm. 200 μm between the two side surfaces of the two second cores 2 with respect to the optical axis 22), the width is 60 μm at the independent part 17, and the width of one second core 2 from DD ′ to EE ′ is 80 μm ( A taper (the upper surface of the first core 1 is an opening) that is reduced from 200 μm between the two side surfaces of the two second cores 2 to 25 μm (90 μm between the two side surfaces of the two second cores 2); The width of one second core 2 up to E ′ is 25 μm (the distance between both side surfaces of the two second cores 2 is 9 μm). 0 μm) to 20 μm (the distance between both side surfaces of the two second cores 2 is 130 μm), the distance from the light incident part 19 is 1.4 mm, and the width is from the light incident part 19 A negative photomask having a second cladding layer 6 having a thickness of 100 μm and an opening that can be formed so as to be a part of the fourth core 4 having a width from EE ′ to the light emitting portion 20 of 130 μm. The light emitting part 20 of one core 1 and the light emitting part 20 formation position of the second cladding layer 6 are matched, and the first core 1 of the independent part 17 is at the center of the second cladding layer 6 forming position. Alignment was performed, and ultraviolet rays (wavelength 365 nm) were irradiated at 2500 mJ / cm ² from the support film side of the resin film for forming the second core and the second cladding layer using the above-described ultraviolet exposure machine. Thereafter, the support film is peeled off, and the uncured second core and second cladding layer forming resin is removed using a developer (1% aqueous potassium carbonate solution), followed by washing with water at 160 ° C. for 1 hour. The dried second core 2 and the second cladding layer 6 were formed by heating and drying. The thickness of the obtained second core 6 was 65 μm, and the thickness of the second cladding layer 6 was (65) μm. Further, the distance from the light incident part 19 to the light emitting part 20 was (8) mm.

[Formation of third cladding layer]
After peeling off the protective film of the third clad layer forming resin film having a thickness of 75 μm obtained above from the surface on which the second core 2 and the second clad layer 6 are formed, a vacuum pressure laminator (Meiki Seisakusho Co., Ltd.) The product was evacuated to 500 Pa or less using a product manufactured by MVLP-500), and then thermocompression bonded under the conditions of a pressure of 0.4 MPa, a temperature of 90 ° C., and a pressurization time of 30 seconds for lamination. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm ² from the support film side of the third cladding layer forming resin film using an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). Thereafter, the support film was peeled off, and dried and cured by heating at 170 ° C. for 1 hour to form a third cladding layer 7 to obtain an optical transmission member. The thickness of the third cladding layer 7 was (75) μm.

[Formation of light incident part and light emission part]
The light incident part 19 of the optical transmission member obtained above and a dicing saw (DAC552, manufactured by DISCO Corporation) provided with a rectangular dicing blade at a position of 8.0 mm in the optical axis direction from the light incident part 19 Then, the substrate 21 was cut together and the end face was smoothed to form the light incident part 19 and the light emitting part 20.

[Optical loss measurement]
Using the GI50 optical fiber as a light emitting element, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the first core 1 of the obtained optical transmission member, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 0.2 dB.
Next, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the third core 3 using a GI50 optical fiber with a coating peeled off as a light emitting element, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 1.2 dB.

[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 19 provided on the first core 1 of the obtained optical transmission member. When the color of the light emitting part 20 was seen from the opposite direction of the optical axis 22, it was uniform white and good. In addition, when the projection plate was placed at a position 5 cm away from the light emitting unit 20 and the projection light was confirmed, the inside of the first core 1 of the light emitting unit 20 was uniform white and good. Since the alignment of the optical fiber was performed while recognizing the first core 1 and the third core 3, the alignment could be easily performed.

Example 2
In Example 1, the distance from DD ′ to FF ′ is set to 3.0 mm, and the width of the first core 1 from DD ′ to FF ′ is gradually expanded from 40 μm to 90 μm, One width from DD ′ to EE ′ of the second core 2 is 80 μm (200 μm between the two side surfaces of the two second cores 2) to 20 μm (between the two side surfaces of the two second cores 2 is 130 μm), and an optical transmission member was fabricated in the same manner except that the distance from the light incident portion 19 to the light emitting portion 20 was 6.0 mm.

[Optical loss measurement]
Using the GI50 optical fiber as a light emitting element, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the first core 1 of the obtained optical transmission member, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 0.2 dB.
Next, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the third core 3 using a GI50 optical fiber with a coating peeled off as a light emitting element, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 1.8 dB.

[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 19 provided on the first core 1 of the obtained optical transmission member. When the color of the light emitting part 20 was seen from the opposite direction of the optical axis 22, the inside of the first core 1 of the light emitting part 20 was uniform white and good. Since the alignment of the optical fiber was performed while recognizing the first core 1 and the third core 3, the alignment could be easily performed.

Example 3
In Example 1, the optical transmission member was formed by the same method except that the third core 3 was not formed and the independent portion 17 of the second core 2 was extended to the light incident portion.

[Optical loss measurement]
Using the GI50 optical fiber as a light emitting element, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the first core 1 of the obtained optical transmission member, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 0.2 dB.
Next, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the third core 3 using a GI50 optical fiber as a light emitting element, and the light emitted from the light emitting portion 20 is used as a light receiving element. Light loss was measured by using an SI114 optical fiber. As a result, it was 1.5 dB.

[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 19 provided on the first core 1 of the obtained optical transmission member. When the color of the light emitting part 20 was seen from the opposite direction of the optical axis 22, the inside of the first core 1 of the light emitting part 20 was uniform white and good. Further, when the projection plate was placed at a position 5 cm away from the light emitting portion 20 and the projection light was confirmed, it was uniform white and good.

Comparative Example 1
In Example 2, a part of the first core 1, the third core 3, and the fourth core 4 is formed of the same material as the second core 2, and the first core 1, the second core 2, the third core 3, The fourth core 4 was manufactured in the same manner except that the same refractive index was used.

[Optical loss measurement]
Using the GI50 optical fiber as a light emitting element, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the first core 1 of the obtained optical transmission member, and the light emitted from the light emitting portion 20 is emitted. The optical loss was measured using an optical fiber of SI114 as the light receiving element. As a result, it was 0.8 dB.
Next, light having a wavelength of 850 nm is incident from the light incident portion 19 provided on the third core 3 using a GI50 optical fiber as a light emitting element, and the light emitted from the light emitting portion 20 is used as a light receiving element. Light loss was measured by using an SI114 optical fiber. As a result, it was 12.0 dB.

[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 19 provided on the first core 1 of the obtained optical transmission member. When the color of the light emitting portion 20 was seen from the direction opposite to the optical axis 22, microscopic interference fringes were observed in the direction perpendicular to the first cladding layer 5.

  The optical transmission member of the present invention can be miniaturized, and at the same time, multiplexes two or more lights with low optical loss, and uniforms the intensity distribution of light of each wavelength on the core surface and / or projection image on the emission side. Optical transmission members capable of obtaining combined light, various optical devices, various optical multiplexing devices, light source units, optical interconnections, medical and industrial endoscopes, illumination devices such as various measuring machines, projectors, It can be applied to a wide range of fields such as pico projectors and image projection devices such as head mounted displays.

1. First core2. Second core3. Third core4. 4. Fourth core First cladding layer6. Second clad layer 7. Third cladding layer8. First taper portion 10. Second taper part A
11. Second taper part B
12 Second taper part C
13. Second taper part D
14 Second taper part E
15. Second taper part F
16. Connection unit 17. Independent part 18. Substantially parallel extending portion 19. Light incident part 20. Light emitting unit 21. Substrate 22. optical axis

Claims (25)

A first core and a second core through which light propagates;
The refractive index of the second core is lower than that of the first core,
A part of a side surface substantially parallel to the optical axis of each of the first core and the second core has a connection part that starts contact;
An optical transmission member having a substantially parallel extending portion in which the first core and the second core extend in substantially the same direction from the connection portion.   The optical transmission member according to claim 1, further comprising a first cladding layer, wherein the first core and the second core are provided on the first cladding layer.   The optical transmission member according to claim 1 or 2, wherein side surfaces of the first core and the second core are in contact with each other in the substantially parallel extending portion.   The optical transmission member according to claim 1, wherein the second core further covers an upper surface of the first core in the substantially parallel extending portion.   5. The optical transmission member according to claim 1, wherein the first core and the second core have an independent portion that extends at least partially with a gap in between.   The optical transmission member according to claim 1, wherein the optical transmission member has two or more second cores, and one or more second cores start contact from both sides of the first core.   The optical transmission member according to claim 5 or 6, wherein at least a part of the independent portion of the first core is covered with a second cladding layer on a side surface or / and an upper surface.   The substantially parallel extending portion has a first taper portion in which a cross-sectional area of the first core in a cross section perpendicular to the extending direction gradually increases from the connecting portion toward the substantially parallel extending portion direction. Item 8. The optical transmission member according to any one of Items 1 to 7.   The optical transmission member according to claim 8, wherein the cross-sectional area is enlarged by enlarging a width of the first core as viewed from the upper surface of a cross section perpendicular to the extending direction.   In the substantially parallel extending portion, a ratio (A / B) of a cross-sectional area A of the second core and a cross-sectional area B of the first core in a vertical cross section with respect to the extending direction is set to be approximately parallel extending from the connecting portion. The optical transmission member according to any one of claims 1 to 9, further comprising a second tapered portion A that gradually decreases in the direction of the existing portion.   The substantially parallel extending portion includes a second taper portion B in which a cross-sectional area of the second core having a cross section perpendicular to the extending direction gradually decreases from the connecting portion toward the substantially parallel extending portion. Item 11. The optical transmission member according to any one of Items 1 to 10.   In the substantially parallel extending portion, a second taper portion C that gradually reduces the width of the second core viewed from the upper surface in a cross section perpendicular to the extending direction from the connecting portion toward the substantially parallel extending portion. The optical transmission member according to claim 1, further comprising a second tapered portion D that gradually increases the width.   At least a part of the taper portion of at least one of the second taper portion A, the second taper portion B, and the second taper portion C has a width of the second core as viewed from the upper surface in a cross section perpendicular to the extending direction. The optical transmission member according to any one of claims 10 to 12, wherein the optical transmission member is a second tapered portion E that is reduced in size so that the cross-sectional area of the second core is reduced.   At least a part of the second taper portion D is a second taper portion F having a cross section perpendicular to the extending direction, the width of the second core viewed from the top surface being reduced, and the cross-sectional area of the second core being reduced. Item 14. The optical transmission member according to Item 12 or 13.   The optical transmission member according to claim 5, further comprising a third core on the optical axis of the second core of the independent part.   The optical transmission member according to any one of claims 1 to 15, further comprising a multiplexing propagation part in a direction opposite to the connection part of the substantially parallel extending part, wherein the multiplexing propagation part has a fourth core.   The optical transmission member according to claim 1, further comprising a light incident portion through which light is incident on each of the first core and the second core.   The optical transmission member according to claim 17, wherein the incident light is light having different wavelengths.   An optical multiplexing device comprising: the light transmission member according to any one of claims 1 to 18; and a light emitting element that emits light from two or more light emitting points to a light incident portion of the light transmission member.   The optical multiplexing device according to claim 19, wherein the light emitting element emits light having specific wavelengths of red, green, and blue from three light emitting points to a light incident portion of the light transmission member.   21. The optical multiplexing device according to claim 20, wherein the light emitting element emits the blue light to the first core of the optical transmission member.   A light source unit using the optical multiplexing device according to claim 20 or 21.   An illumination device using the optical multiplexing device according to claim 20 or 21.   An image projection apparatus using the optical multiplexing device according to claim 20 or 21.   The method of manufacturing an optical transmission member according to claim 1, wherein the second core and the second cladding layer are patterned simultaneously, and the second core and the fourth core are patterned simultaneously. A method for manufacturing an optical transmission member, comprising: at least one of a step, a step of simultaneously patterning the first core and the third core, and a step of simultaneously patterning the first core and the fourth core. .