JPH09105834A - Coupling structure for optical waveguide and optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure which suppresses the deterioration in the propagation characteristic of light of optical waveguides in the coupling structure for the optical waveguides and optical fibers using dolly plates. SOLUTION: The dolly plates 22 and 30 are fixed onto both ends of an LiNbO3 substrate 11 formed with the Ti-diffused optical waveguide 13. The recessed part 24 of the dolly plate 22 is disposed on the optical waveguides 16 and 17 and the recessed part 34 of the dolly plate 30 is disposed on the optical waveguide 15 to prevent the direct contact of the bases of the dolly plates 22 and 30 with the optical waveguides 15, 16, 17. The dolly plate 22 reinforces the joining of the LiNbO3 substrate 11, a ceramic substrate 62 holding the bare optical fiber 70 and a quartz cap 64. The dolly plate 30 plays the role of joining of the LiNbO3 substrate 11, a ceramic substrate 82 holding the bare optical fiber 90 and a quartz cap 84.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling structure for an optical waveguide and an optical fiber, and more particularly to an optical waveguide using a sharpening plate for reinforcing the coupling between the optical waveguide chip having the optical waveguide and the optical fiber. The present invention relates to a coupling structure with an optical fiber.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view for explaining a conventional coupling structure between an optical waveguide and an optical fiber.

In this conventional optical waveguide / optical fiber coupling structure, a sharpening plate 206 is provided on one end of a LiNbO ₃ substrate 202 having a Ti diffusion optical waveguide 204 formed thereon, and an optical fiber 210 is provided with an adhesive. 208 by L
It is fixed to the iNbO ₃ substrate 202 and the edge plate 206. By using the edge plate 206 in this way, the fixation between the optical fiber 210 and the LiNbO ₃ substrate 202 is reinforced.

[0004]

However, since the bottom surface of the conventional baffle plate is flat over the entire surface,
It was also provided directly on the Ti diffusion optical waveguide 204. Therefore, the present inventor found that there is a problem in that stress is applied to the Ti diffusion optical waveguide 204 by the plate 206, and the light propagation characteristics, particularly the polarization characteristics are deteriorated. In particular, when an optical fiber such as an optical fiber for a fiber gyro having important polarization characteristics is used as the optical fiber 210, it is important not to deteriorate the polarization characteristics of the Ti diffusion optical waveguide 204.

Therefore, an object of the present invention is to provide a coupling structure of an optical waveguide and an optical fiber which uses a sill plate and which suppresses deterioration of light propagation characteristics of the optical waveguide. To provide.

[0006]

According to the present invention, an optical waveguide chip having one main surface, an optical waveguide formed on the one main surface, and one end surface from which one end of the optical waveguide is exposed,
An optical fiber is provided on the one main surface near the one end surface to cover the optical waveguide, and an optical fiber, and the optical fiber is optically coupled to the optical waveguide. A fiber is fixed to the one end face of the optical waveguide chip, and the fixation to the one end face of the optical fiber is reinforced by the grate plate. In the coupling structure of the optical waveguide and the optical fiber, There is provided a coupling structure between an optical waveguide and an optical fiber, characterized in that a concave portion is provided on the bottom surface of the plate so that the bottom surface of the slab is not in direct contact with the optical waveguide.

As described above, if the bottom surface of the sharpening plate is provided with a recess so that the bottom surface of the sharpening plate does not come into direct contact with the optical waveguide, the stress applied to the optical waveguide by the sharpening plate is reduced, As a result, it is possible to suppress the deterioration of the light propagation characteristics of the optical waveguide below the cutting board.

It is preferable that the one end surface of the optical fiber is fixed to the one end surface through an optical fiber holding member that holds the optical fiber. By doing so, the fixation of the optical fiber to the optical waveguide chip becomes more robust.
As the optical fiber holding member, for example, a V groove is formed in a ceramic substrate, the optical fiber is placed in the V groove, and a lid is placed on the V fiber. An optical fiber holding member having a fixed structure is preferably used.

The side of the recess on the bottom surface of the cutting board and the optical waveguide are preferably separated by 0.1 mm or more, more preferably 0.5 mm or more.

It is desirable that the material of the cutting board is similar to or the same as that of the substrate of the optical waveguide chip.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view for explaining a coupling structure between an optical waveguide and an optical fiber according to an embodiment of the present invention, and FIG. 2 is an optical waveguide according to an embodiment of the present invention. It is a perspective view for explaining a coupling structure with an optical fiber,
FIG. 3 is an exploded perspective view for explaining an optical waveguide chip used in the coupling structure of the optical waveguide and the optical fiber according to the embodiment of the present invention.

In the present embodiment, the optical fiber gyro 1 is provided with the coupling structure of the optical waveguide and the optical fiber of the present invention.
00 was applied.

The optical fiber gyro 100 includes an optical waveguide chip assembly 50, an optical fiber loop assembly 60, and a light emitting / receiving element assembly 80.

The optical fiber loop assembly 60 includes a ceramic substrate 62, a quartz lid 64, and an optical fiber loop 6.
8 is provided. On the upper surface of the ceramic substrate 62,
A V groove 66 having a V-shaped cross section is provided. The bare optical fibers 70 at both ends of the optical fiber loop 68 from which the coating portion of the optical fiber is removed are inserted into the V-groove 66 and the ceramic substrate 62.
And, it is fixed by a quartz lid 64 using a resin adhesive. The coating portion of the optical fiber is accommodated by a recess 72 provided in the rear portion of the upper surface of the ceramic substrate 62 and a recess 74 provided in the rear portion of the lower surface of the quartz lid 64. The end surface 76 of the ceramic substrate 62 and the end surface 78 of the quartz lid 64 are provided by being optically polished so as to form a single plane.

The light emitting / receiving element assembly 80 comprises a ceramic substrate 82, a quartz lid 84, and optical fibers 88, 92.
A laser diode 96 and a photodiode 98. A V groove 86 having a V-shaped cross section is provided on the upper surface of the ceramic substrate 82. A bare optical fiber 90 at one end of the optical fiber 88 from which the coating portion of the optical fiber is removed is fixed in the V groove 86 by a ceramic substrate 82 and a quartz lid 84 using a resin adhesive. The optical fiber coating is a ceramic substrate 82.
It is accommodated by a recessed portion 83 provided in the rear portion of the upper surface and a recessed portion 85 provided in the rear portion of the lower surface of the quartz lid 84. The end surface 87 of the ceramic substrate 82 and the end surface 89 of the quartz lid 84 are provided by being optically polished so as to form a single plane. The optical fiber 88 and the optical fiber 92 are fused together to form a branching / coupling device 94. Optical fiber 8
A laser diode 96 is attached to the other end of 8,
A photodiode 98 is attached to one end of the optical fiber 92.

The optical waveguide chip assembly 50 is an optical waveguide chip assembly.
It is provided with a top plate 10 and a pair of blades 22 and 30. light
The waveguide chip 10 is made of LiNbO._ThreeSubstrate 11 and LiN
bO _ThreeTi diffused optical waveguide provided on the upper surface 12 of the substrate 11
Comprises a path 13, a phase modulator 18 and a polarizer 20.
You. In the Ti diffusion optical waveguide 13, one optical waveguide 15 is
Two optical waveguides 16 and 17 are provided in the Y branch portion 14.
It is branched. The polarizer 20 is provided on the optical waveguide 15.
Have been. Phase modulators 18 are provided on both sides of the optical waveguide 16.
The two electrodes 19 for forming the optical waveguide are provided.
Two wires to configure the phase modulator 18 on both sides of the path 17
Electrode 19 is provided.

A recess 24 is provided at the center of the bottom surface 23 of the cutting board 22. A recess 34 is provided at the center of the bottom surface 32 of the cutting board 30.

On the upper surface 12 near the end surface 41 of the LiNbO ₃ substrate 11 where the end portions of the optical waveguides 16 and 17 are exposed, a sharpening plate 22 is fixed by using a resin adhesive. A recess 24 is provided directly above the optical waveguides 16 and 17.
Is provided, the bottom surface 23 of the cutting board 22 is not in contact with the optical waveguides 16 and 17. The side portion 26 of the recess 24 is separated from the optical waveguide 16 by a distance x, and the side portion 28 of the recess 24 is also separated from the optical waveguide 17 by a distance x. LiNb
The end surface 41 of the O ₃ substrate 11 and the end surface 43 of the shroud plate 22 are provided by being optically polished so as to form a single plane.

The optical waveguide chip assembly 50 and the optical fiber loop assembly 60 are arranged so that the optical waveguide 16 and the bare optical fiber 70 and the optical waveguide 17 and the bare optical fiber 70 are optically coupled, respectively. End face 78 of the ceramic substrate 62 and the end face 78 of the quartz lid 64 in the closed state.
And the end face 41 of the LiNbO ₃ substrate 11 and the edge plate 2
The second end surface 43 is fixed by a resin adhesive.

LiNbO in which the end of the optical waveguide 15 is exposed
_{3 On} the upper surface 12 in the vicinity of the end surface 45 of the substrate 11, a sharpening plate 30 is fixed by using a resin adhesive. Since the concave portion 34 is provided immediately above the optical waveguide 15,
The bottom surface 32 of the plate 30 is not in contact with the optical waveguide 15. The sides 36 and 38 of the recess 34 are both the optical waveguide 1.
It is a distance x away from 5. The end face 45 of the LiNbO ₃ substrate 11 and the end face 47 of the sharpening plate 30 are provided by being optically polished so as to form a single plane.

The end face of the ceramic substrate 82 is provided with the optical waveguide chip assembly 50 and the light emitting / receiving element assembly 80 so that the optical waveguide 15 and the bare optical fiber 90 are optically coupled. 87 and end face 89 of quartz lid 84
And the end surface 45 of the LiNbO ₃ substrate 11 and the edge plate 3
The end surface 47 of 0 is fixed by a resin adhesive.

In order to confirm the effect of the present invention, the distance x between the optical waveguide 15 and the side portions 36 and 38 of the concave portion 34 of the baffle plate 30, the side portion 26 of the concave portion 24 of the optical waveguide 16 and the baffle plate 22. And the distance x, and the optical waveguide 17 and the plate 22
The distance x from the side portion 28 of the recess 24 is 0.05 m
m, 0.1 mm, 0.3 mm, 0.5 mm and 0.7
A total of 6 types of optical waveguide chip assemblies 50 are formed, including 5 types of optical waveguide chip assemblies 50 having a size of mm and optical waveguide chip assemblies 50 using the chamfer plates 22 and 30 in which the recesses 24 and 34 are not provided. Then, the respective polarization extinction ratios were measured.

L having a thickness of 1 mm, a width of 5 mm and a length of 30 mm
An iNbO ₃ substrate 11 is used, a Ti diffusion optical waveguide 13 is provided on the upper surface 12, and a phase modulator 18 having a pitch interval of 250 μm.
Then, the polarizer 20 was formed to form the optical waveguide chip 10.

Li having a thickness of 2 mm, a width of 5 mm and a length of 5 mm
Using NbO ₃ sharpening plates 22 and 30, their bottom surfaces 23 and 32 are mirror-polished, and a recess 24 having a depth of 0.5 mm at the center of each bottom and varying its width and 34 were formed respectively. Board 22
The and 30, secured by an epoxy resin on the upper surface 12 of the LiNbO ₃ substrate 11, LiNbO ₃ and the end face 43 of the end face 41 and Hire plate 22 of the substrate 11, LiNbO ₃ end face 47 of the end face 45 and Hire plate 30 of the substrate 11 And
Each was mirror-polished to form an optical waveguide chip assembly 50.

Next, the polarization extinction ratio of this optical waveguide chip assembly 50 was measured, and the results shown in Table 1 were obtained. In addition, the optical waveguide chip 1 before fixing the edge plates 22 and 30
The polarization extinction ratio of 0 was 50 dB.

[0027]

[Table 1]

The distance x between the optical waveguide 15 and the side portions 36 and 38 of the recess 34 of the shroud plate 30, the distance x between the optical waveguide 16 and the side portion 26 of the recess 24 of the shroud plate 22, and the optical waveguide 17. Distance x from side surface 28 of recess 24 of plate 22
However, if it is 0.1 mm or more, there is no problem in practical use and 0.
It has been found that if it is 5 mm or more, it will not be affected even if a sharp plate is provided.

[0029]

According to the present invention, an optical waveguide chip having one main surface, an optical waveguide formed on the one main surface, and one end surface at which one end of the optical waveguide is exposed; An optical fiber is provided on the one main surface so as to cover the optical waveguide, and an optical fiber, wherein the optical fiber is optically coupled to the optical waveguide. In the coupling structure of the optical waveguide and the optical fiber, which is fixed to the one end surface of the chip, and the fixing to the one end surface of the optical fiber is reinforced by the cutting board, a recess is formed in the bottom surface of the cutting board. Since the bottom surface of the sill plate is not in direct contact with the optical waveguide, the stress applied to the optical waveguide by the sill plate is reduced, and as a result, the light below the sill plate is reduced. Light propagation characteristics of waveguide Being degraded can be suppressed.

Further, by fixing the optical fiber to the one end face via the optical fiber holding member for holding the optical fiber, the optical fiber is more firmly fixed to the optical waveguide chip. Will be things.

Further, by separating the side portion of the concave portion on the bottom surface of the cutting board from the optical waveguide by 0.1 mm or more,
Even if the sharp plate is provided, the deterioration of the characteristics caused in the optical waveguide due to the provision of the sharp plate is practically no problem.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining a coupling structure between an optical waveguide and an optical fiber according to an embodiment of the present invention.

FIG. 2 is a perspective view for explaining the coupling structure between the optical waveguide and the optical fiber according to the embodiment of the present invention.

FIG. 3 is an exploded perspective view for explaining an optical waveguide chip used in the coupling structure of the optical waveguide and the optical fiber according to the embodiment of the present invention.

FIG. 4 is a perspective view for explaining a conventional coupling structure of an optical waveguide and an optical fiber.

[Explanation of symbols]

10 ... Optical waveguide chip, 11 ... LiNbO ₃ substrate, 12
... Top surface, 13 ... Ti diffusion optical waveguide, 14 ... Y branch portion, 1
5 ... Optical waveguide, 16 ... Optical waveguide, 17 ... Optical waveguide, 18
... phase modulator, 19 ... Electrode, 20 ... Polarizer, 22 ... Ground plate, 23 ... Bottom, 24 ... Recess, 26 ... Side, 28 ... Side, 30 ... Ground plate, 32 ... Bottom, 34 ... Recess, 36 ...
Side part, 38 ... Side part, 41 ... End face, 43 ... End face, 45 ... End face, 47 ... End face, 50 ... Optical waveguide chip assembly, 60 ...
Optical fiber loop assembly, 62 ... Ceramics substrate, 6
4 ... Quartz lid, 66 ... V groove, 68 ... Optical fiber loop,
70 ... Naked optical fiber, 72 ... Recessed part, 74 ... Recessed part, 76 ...
End face, 78 ... End face, 80 ... Emitting / light receiving element assembly, 82 ...
Ceramic substrate, 83 ... Recessed portion, 84 ... Quartz lid, 85
... concave portion, 86 ... V groove, 87 ... end face, 88 ... optical fiber,
89 ... End face, 90 ... Bare optical fiber, 92 ... Optical fiber,
94 ... Branch / combiner, 96 ... Laser diode, 98
… Photodiode, 100… Optical fiber gyro, 20
2 ... LiNbO ₃ substrate, 204 ... Ti diffusion optical waveguide, 2
06 ... glue plate, 208 ... adhesive, 210 ... optical fiber

Claims (3)

[Claims] 1. An optical waveguide chip having one main surface, an optical waveguide formed on the one main surface, and one end surface where one end of the optical waveguide is exposed, and on the one main surface near the one end surface. And a fiber optic plate provided to cover the optical waveguide, and the optical fiber is optically coupled to the optical waveguide, the optical fiber is the one end surface of the optical waveguide chip. Is fixed to the one end surface of the optical fiber is reinforced by the baffle plate, in the coupling structure of the optical waveguide and the optical fiber, a recess is provided in the bottom surface of the baffle plate, A coupling structure between an optical waveguide and an optical fiber, wherein the bottom surface of the shroud is not in direct contact with the optical waveguide. 2. The optical waveguide and the optical fiber according to claim 1, wherein the fixing to the one end face of the optical fiber is performed through an optical fiber holding member that holds the optical fiber. Bonding structure with. 3. A side portion of the concave portion and the optical waveguide form an O.V. 1
3. The coupling structure between the optical waveguide and the optical fiber according to claim 1, wherein the coupling structure is separated by at least mm.