Optical waveguide device

Abstract

To reduce optical coupling losses of bonded two optical waveguides.SOLUTION: An optical waveguide device comprises a first optical waveguide, a second optical waveguide, and an adhesive layer. The first optical waveguide includes a first clad, and a first core the tip of which is exposed from the first clad. The second optical waveguide includes a second clad created from the same material as the first clad, and a second core the tip of which is exposed from the second clad and which is created from the same material as the first core. The adhesive layer bonds the first optical waveguide and the second optical waveguide together in the state of the tip of the first core and the tip of the second core are arranged partially overlapping each other. The adhesive layer fills a gap between the first clad and the second clad to cover the sides of the tips of the first and second cores, and has a refractive index closer to the refractive indices of the first and second clads than the refractive indices of the first and second cores.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an optical waveguide device.

Background Art

[0002] Conventionally, an optical waveguide device that optically couples two optical waveguides by adhesion has been known. Each of the two optical waveguides is composed of a cladding and a core with a part of its surface exposed from the cladding.

[0003] When optically coupling two optical waveguides, after the exposed surface of the core in one optical waveguide and the exposed surface of the core in the other optical waveguide are overlapped in plan view, the exposed surface of the core in one optical waveguide and the exposed surface of the core in the other optical waveguide are adhered via an adhesive layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when an adhesive layer is interposed between the exposed surface of the core in one optical waveguide and the exposed surface of the core in the other optical waveguide, the movement of light between the cores is hindered, and there is a problem that the optical coupling loss between the two optical waveguides to be adhered increases. That is, since the refractive index of the adhesive layer interposed between the cores of the two optical waveguides is adjusted to a refractive index relatively close to the refractive indices of the cores of the two optical waveguides, the light moving from one core to the other core leaks to the outside of the optical waveguide through the adhesive layer, and the optical coupling loss increases.

[0006] The disclosed technology has been made in view of the above, and an object thereof is to provide an optical waveguide device capable of reducing the optical coupling loss between two optical waveguides to be adhered.

Means for Solving the Problem

[0007] The optical waveguide device disclosed in the present application, in one aspect, has a first optical waveguide, a second optical waveguide, and an adhesive layer. The first optical waveguide has a first cladding and a first core whose tip is exposed from the first cladding. The second optical waveguide has a second cladding made of the same material as the first cladding and a second core whose tip is exposed from the second cladding and made of the same material as the first core. The adhesive layer adheres the first optical waveguide and the second optical waveguide in a state where the tip of the first core and the tip of the second core are partially overlapped. The adhesive layer fills the space between the first cladding and the second cladding to cover the side surfaces of the tip of the first core and the tip of the second core, and has a refractive index closer to the refractive indices of the first cladding and the second cladding than the refractive indices of the first core and the second core.

Advantages of the Invention

[0008] According to one aspect of the optical waveguide device disclosed in the present application, there is an effect that the optical coupling loss between two optical waveguides to be adhered can be reduced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

[0010] Hereinafter, embodiments of the optical waveguide device disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed technology is not limited by this embodiment.

[0011] FIG. 1 is a plan view showing the configuration of an optical waveguide device 100 according to an embodiment. FIG. 2 is a diagram schematically showing a cross section taken along line II-II in FIG. 1. FIG. 3 is a diagram schematically showing a cross section taken along line III-III in FIG. 2. FIG. 4 is a diagram schematically showing a cross section taken along line IV-IV in FIG. 2. FIG. 5 is a diagram schematically showing a cross section taken along line V-V in FIG. 2.

[0012] As shown in FIGS. 1 and 2, the optical waveguide device 100 is configured by bonding a first optical waveguide 110 and a second optical waveguide 120 with an adhesive layer 130.

[0013] The first optical waveguide 110 includes a first cladding 111 and a first core 112.

[0014] The first cladding 111 is made of a transparent material such as a thermosetting or photocurable epoxy resin or silicon dioxide (SiO 2 2) and is configured to surround one end portion of the first core 112 (hereinafter referred to as "base end portion 112a"). The first cladding 111 is made of a material having a refractive index different from that of the first core 112, and totally reflects the light in the first core 112 at the interface with the first core 112.

[0015] As shown in FIGS. 2 and 5, the first cladding 111 includes a first lower cladding 111a and a first upper cladding 111b, and surrounds a base end portion 112a of a first core 112 formed on the first lower cladding 111a with the first lower cladding 111a and the first upper cladding 111b. The first upper cladding 111b is formed on the first lower cladding 111a so as to cover the base end portion 112a of the first core 112 except for the other end portion of the first core 112 (hereinafter referred to as the “tip end portion 112b”). The first cladding 111 exposes the tip end portion 112b of the first core 112 in a region of the first lower cladding 111a that does not overlap the first upper cladding 111b in plan view.

[0016] The first core 112 is a passage for transmitting light. The first core 112 is made of a transparent material such as a thermosetting or photocurable epoxy resin or silicon (Si), and has a base end portion 112a and a tip end portion 112b as shown in FIGS. 1 and 2. The base end portion 112a of the first core 112 is a portion surrounded by the first cladding 111 (that is, the first lower cladding 111a and the first upper cladding 111b). The end face of the base end portion 112a is exposed on the side surface of the first optical waveguide 110 and serves as a connection surface to which an optical transmission component such as an optical fiber is connected. The tip end portion 112b of the first core 112 is a portion exposed from the first cladding 111 in a region of the first lower cladding 111a that does not overlap the first upper cladding 111b in plan view. The tip end portion 112b of the first core 112 is disposed so as to partially overlap with the tip end portion 122b of a second core 122 described later. The first core 112 transmits the light leaking from the tip end portion 122b to the tip end portion 112b of the second core 122 in the longitudinal direction of the first core 112 and guides it to the end face of the base end portion 112a.

[0017] The second optical waveguide 120 has a second cladding 121 and a second core 122.

[0018] The second cladding 121 is made of the same material as the first cladding 111 and is configured to surround one end portion of the second core 122 (hereinafter referred to as the “base end portion 122a”). The second cladding 121 is made of a material having a refractive index different from that of the second core 122, and totally reflects the light in the second core 122 at the interface with the second core 122.

[0019] As shown in FIGS. 2 and 3, the second cladding 121 includes a second lower cladding 121a and a second upper cladding 121b, and the base end portion 122a of the second core 122 formed on the second lower cladding 121a is surrounded by the second lower cladding 121a and the second upper cladding 121b. The second upper cladding 121b is formed on the second lower cladding 121a so as to cover the base end portion 122a of the second core 122 except for the other end portion of the second core 122 (hereinafter referred to as the “tip end portion 122b”). The second cladding 121 exposes the tip end portion 122b of the second core 122 in a region of the second lower cladding 121a that does not overlap with the second upper cladding 121b in plan view.

[0020] The second core 122 is a path for transmitting light. The second core 122 is made of the same material as the first core 112 and has a base end portion 122a and a tip end portion 122b as shown in FIGS. 1 and 2. The base end portion 122a of the second core 122 is a portion surrounded by the second cladding 121 (that is, the second lower cladding 121a and the second upper cladding 121b). The end face of the base end portion 122a is exposed on the side surface of the second optical waveguide 120 and serves as a connection surface to which an optical transmission component such as an optical fiber is connected. The tip end portion 122b of the second core 122 is a portion exposed from the second cladding 121 in a region of the second lower cladding 121a that does not overlap with the second upper cladding 121b in plan view. The tip end portion 122b of the second core 122 is disposed so as to partially overlap with the tip end portion 112b of the first core 112. The tip end portion 122b of the second core 122 has a tapered shape in which the core width becomes smaller toward the tip end. The second core 122 transmits the light incident from the end face of the base end portion 122a in the longitudinal direction of the second core 122 and leaks it from the tip end portion 122b to the tip end portion 112b of the first core 112.

[0021] The adhesive layer 130 is made of a material such as a thermosetting or photocurable epoxy resin, and adheres the first optical waveguide 110 and the second optical waveguide 120 in a state where the tip 112b of the first core 112 and the tip 122b of the second core 122 are partially overlapped. Specifically, as shown in FIGS. 2 and 4, the adhesive layer 130 adheres the first cladding 111 in the first optical waveguide 110 and the second cladding 121 in the second optical waveguide 120.

[0022] In the embodiment, the adhesive layer 130 fills the space between the first cladding 111 and the second cladding 121 and covers the side surfaces of the tip 112b of the first core 112 and the tip 122b of the second core 122. And the adhesive layer 130 has a refractive index closer to the refractive indices of the first cladding 111 and the second cladding 121 than the refractive indices of the first core 112 and the second core 122. That is, the adhesive layer 130 is formed of a material having a refractive index that totally reflects the light in the first core 112 and the light in the second core 122 at the interface with the first core 112 and the second core 122, similar to the first cladding 111 and the second cladding 121. Therefore, it is possible to suppress the light moving from the second core 122 to the first core 112 from leaking to the outside of the optical waveguide through the adhesive layer 130. As a result, the optical coupling loss between the first optical waveguide 110 and the second optical waveguide 120 to be adhered can be reduced.

[0023] Also, in the embodiment, as shown in FIG. 2, the adhesive layer 130 covers the end faces of the tip 112b of the first core 112 and the tip 122b of the second core 122. Therefore, it is possible to suppress the leakage of light from the end faces of the tip 112b of the first core 112 and the tip 122b of the second core 122. As a result, the optical coupling loss between the first optical waveguide 110 and the second optical waveguide 120 to be adhered can be further reduced.

[0024] Next, a method for manufacturing the optical waveguide device 100 configured as described above will be described. Hereinafter, after describing the manufacturing method of the first optical waveguide 110 and the manufacturing method of the second optical waveguide 120, the manufacturing method of the optical waveguide device 100 having the first optical waveguide 110 and the second optical waveguide 120 will be described.

[0025] FIG. 6 is a flowchart showing a method of manufacturing the first optical waveguide 110 according to the embodiment.

[0026] First, a first lower cladding 111a is formed on a base material (not shown) (step S101). Specifically, for example, an epoxy resin in a semi-cured state disposed on the base material is cured by heating or irradiation with light such as ultraviolet rays to form the first lower cladding 111a.

[0027] Then, a first core 112 is formed on the first lower cladding 111a (step S102). Specifically, for example, an epoxy resin in a semi-cured state disposed and shaped on the first lower cladding 111a is cured by heating or irradiation with light such as ultraviolet rays to form the first core 112. For example, a rectangular parallelepiped-shaped first core 112 extending from one end of the first lower cladding 111a to a position that does not reach the other end of the first lower cladding 111a is formed.

[0028] Then, a first upper cladding 111b that covers the base end portion 112a of the first core 112 is formed on the first lower cladding 111a (step S103). Specifically, for example, an epoxy resin in a semi-cured state disposed on the first lower cladding 111a so as to cover the base end portion 112a of the first core 112 is cured by heating or irradiation with light such as ultraviolet rays to form the first upper cladding 111b. Here, in a region of the first lower cladding 111a that does not overlap with the first upper cladding 111b in plan view, the tip portion 112b of the first core 112 is exposed from the first cladding 111. Thereby, the first optical waveguide 110 in which the tip portion 112b of the first core 112 is exposed from the first cladding 111 is completed. Note that, if necessary, the base material may be peeled off from the first lower cladding 111a.

[0029] Next, FIG. 7 is a flowchart showing a method of manufacturing the second optical waveguide 120 according to the embodiment.

[0030] First, a second lower cladding 121a is formed on a substrate (not shown) (step S111). Specifically, for example, an epoxy resin in a semi-cured state disposed on the substrate is cured by heating or irradiation with light such as ultraviolet rays to form the second lower cladding 121a.

[0031] Then, a second core 122 is formed on the second lower cladding 121a (step S112). Specifically, for example, an epoxy resin in a semi-cured state disposed and shaped on the second lower cladding 121a is cured by heating or irradiation with light such as ultraviolet rays to form the second core 122. For example, the second core 122 having a rectangular parallelepiped-shaped base end portion 112a and a tapered tip portion 122b is formed to extend from one end of the second lower cladding 121a to a position that does not reach the other end of the second lower cladding 121a.

[0032] Then, a second upper cladding 121b that covers the base end portion 122a of the second core 122 is formed on the second lower cladding 121a (step S113). Specifically, for example, an epoxy resin in a semi-cured state disposed on the second lower cladding 121a so as to cover the base end portion 122a of the second core 122 is cured by heating or irradiation with light such as ultraviolet rays to form the second upper cladding 121b. Here, in a region of the second lower cladding 121a that does not overlap with the second upper cladding 121b in plan view, the tip portion 122b of the second core 122 is exposed from the second cladding 121. Thereby, the second optical waveguide 120 in which the tip portion 122b of the second core 122 is exposed from the second cladding 121 is completed. Note that, if necessary, the substrate may be peeled off from the second lower cladding 121a.

[0033] Next, FIG. 8 is a flowchart showing a method for manufacturing the optical waveguide device 100 according to the embodiment. The optical waveguide device 100 is manufactured using the first optical waveguide 110 and the second optical waveguide 120 described above.

[0034] First, an adhesive layer 130 is formed on the second optical waveguide 120 (step S121). Specifically, an epoxy resin in a semi-cured state is applied to a region located around the tip portion 122b of the second core 122 in a region of the second lower cladding 121a that does not overlap with the second upper cladding 121b in a plan view, thereby forming the semi-cured adhesive layer 130.

[0035] Subsequently, alignment is performed between the first core 112 in the first optical waveguide 110 and the second core 122 in the second optical waveguide 120 (step S122). Specifically, alignment is performed such that the tip portion 112b of the first core 112 and the tip portion 122b of the second core 122 are partially overlapped and arranged.

[0036] Subsequently, the first optical waveguide 110 and the second optical waveguide 120 are adhered by the adhesive layer 130 in a state where the tip portion 112b of the first core 112 and the tip portion 122b of the second core 122 are partially overlapped (step S123). Specifically, first, the first cladding 111 in the first optical waveguide 110 and the second cladding 121 in the second optical waveguide 120 are adhered by the adhesive layer 130. At this time, the adhesive layer 130 is filled between the first cladding 111 and the second cladding 121, covering the side surfaces and end surfaces of the tip portion 112b of the first core 112 and the tip portion 122b of the second core 122. Then, the adhesive layer 130 is thermally cured. Thereby, an optical waveguide device 100 in which the first optical waveguide 110 and the second optical waveguide 120 are adhered by the adhesive layer 130 having a refractive index closer to the refractive indices of the first cladding 111 and the second cladding 121 than the refractive indices of the first core 112 and the second core 122 is obtained.

[0037] In the above embodiment, the case where the tip portion 122b of the second core 122 has a tapered shape in which the core width becomes smaller toward the tip is exemplified, but the tip portion 112b of the first core 112 may have a tapered shape.

[0038] As described above, the optical waveguide device according to the embodiment (for example, the optical waveguide device 100) includes a first optical waveguide (for example, the first optical waveguide 110), a second optical waveguide (for example, the second optical waveguide 120), and an adhesive layer (for example, the adhesive layer 130). The first optical waveguide includes a first cladding (for example, the first cladding 111) and a first core (for example, the first core 112) with a tip portion (for example, the tip portion 112b) exposed from the first cladding. The second optical waveguide includes a second cladding (for example, the second cladding 121) made of the same material as the first cladding and a second core (for example, the second core 122) with a tip portion (for example, the tip portion 122b) exposed from the second cladding and made of the same material as the first core. The adhesive layer adheres the first optical waveguide and the second optical waveguide in a state where the tip portion of the first core and the tip portion of the second core are partially overlapped. The adhesive layer fills the space between the first cladding and the second cladding to cover the side surfaces of the tip portions of the first core and the second core, and has a refractive index closer to that of the first cladding and the second cladding than that of the first core and the second core. Thereby, the optical coupling loss between the two optical waveguides to be adhered can be reduced.

[0039] The adhesive layer may cover the end faces of the tip portion of the first core and the tip portion of the second core. Thereby, the optical coupling loss between the two optical waveguides to be adhered can be further reduced.

[0040] The tip portion of the first core or the tip portion of the second core may have a tapered shape in which the core width decreases toward the tip. Thereby, the optical coupling loss between the two optical waveguides to be adhered can be further reduced.

Explanation of Reference Numerals

[0041] 100 Optical waveguide device 110 First optical waveguide 111 First cladding 111a First lower cladding 111b First upper cladding 112 First core 112a Base end portion 112b Tip portion 120 Second optical waveguide 121 Second cladding 121a Second lower cladding 121b Second upper cladding 122 Second core 122a Base end portion 122b Tip end portion 130 Adhesive layer

Claims

1. A first optical waveguide having a first cladding and a first core with a tip exposed from the first cladding, a second optical waveguide having a second cladding made of the same material as the first cladding and a second core with a tip exposed from the second cladding and made of the same material as the first core, and an adhesive layer that adheres the first optical waveguide and the second optical waveguide in a state where the tips of the first core and the second core are partially overlapped. It has, The adhesive layer, fills the space between the first cladding and the second cladding to cover the side surfaces of the tips of the first core and the second core, and has a refractive index closer to the refractive indices of the first cladding and the second cladding than the refractive indices of the first core and the second core. An optical waveguide device characterized by this.

2. The adhesive layer, covers the end faces of the tips of the first core and the second core. The optical waveguide device according to claim 1, characterized by this.

3. The tip of the first core or the tip of the second core, has a tapered shape in which the core width decreases toward the tip. The optical waveguide device according to claim 1, characterized by this.

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