JPH04104107A - Connection structure between plane optical waveguide and optical fiber - Google Patents

Abstract

PURPOSE:To offer the connection structure between the plane optical waveguide and optical fiber which can be increased in connection strength by putting the flat surfaces of a plane optical waveguide substrate and an optical fiber holding substrate one over the other and fixing them with an optical adhesive agent. CONSTITUTION:The plane optical waveguide substrate 1 and optical fiber holding substrate 2 having slanting side end surfaces 1c and 2c having the same angle, e.g. 45 deg., the end surface of the plane optical waveguide 1b is exposed to the slanting surface 1c, and the end surface of the optical fiber 2b is put away from the slanting surface 2c and not exposed. The slanting surfaces 1c and 2c of the plane optical waveguide substrate 1 and optical fiber holding substrate 2 are set opposite each other, put one over the other, and fixed with the optical adhesive so that light travels as shown by an arrow. For the improvement of the optical coupling efficiency, a plane lens 3, i.e. converging grating lens (diffraction grating) is stuck on the slanting surface 2c of the optical fiber holding substrate 2. Consequently, light is reflected by the slanting surfaces and coupled optically and the superposition area increases on the plane, so the connection strength is increased.

Description

[Detailed Description of the Invention] [Summary] In order to strengthen the connection strength with respect to a connection structure between a planar optical waveguide and an optical fiber, a planar optical waveguide is provided on one flat surface of a crystal substrate having flat front and back surfaces. Consisting of an optical waveguide substrate and an optical fiber holding substrate in which an optical fiber is embedded in a crystal substrate having flat front and back surfaces, the side end surfaces of the planar optical waveguide substrate and the optical fiber holding substrate are sloped at the same angle, and the slopes face each other. The flat surfaces of the planar optical waveguide substrate and the optical fiber holding substrate are overlapped and fixed together with an optical adhesive so as to optically couple the planar optical waveguide substrate and the optical fiber holding substrate.

[Industrial Application Field] The present invention relates to a connection structure between a planar optical waveguide and an optical fiber.

Although the end faces of a planar optical waveguide and an optical fiber are connected using an optical adhesive, there is a need to strengthen the connection strength.

[Conventional technology]

A conventional connection structure between a planar optical waveguide and an optical fiber is, as shown in the perspective view of FIG. The optical fiber/N 101 is connected to the planar optical waveguide 100 by aligning the end surfaces of the optical fibers 101 and 101 linearly.
After adjustment within the end surface of a, the parts were fixedly connected using an optical adhesive (not shown).

[Problems to be Solved by the Invention] However, according to the above connection structure, the planar optical waveguide is located on the surface of the crystal substrate, and the diameter of the optical fiber is as small as 125 μm, so the fixed area is large. There was a problem that the connection strength was low and the connection became unstable because it could not be removed.

In view of the above problems, an object of the present invention is to provide a connection structure between a planar optical waveguide and an optical fiber, which can strengthen the connection strength.

[Means for Solving the Problem] In order to achieve the above object, in the connection structure between a planar optical waveguide and an optical fiber of the present invention, a planar optical waveguide is provided on one flat surface of a crystal substrate having flat front and back surfaces. It consists of a planar optical waveguide substrate and an optical fiber holding substrate in which an optical fiber is embedded in a crystal substrate having flat front and back surfaces, the side end surfaces of the planar optical waveguide substrate and the optical fiber holding substrate are sloped at the same angle, and the slopes are The flat surfaces of the planar optical waveguide substrate and the optical fiber holding substrate are overlapped and fixed with an optical adhesive so that they face each other and are optically coupled.

(The planar optical waveguide substrate and the optical fiber/holding substrate are arranged so that their side end surfaces, which are inclined planes, face each other, and the flat surfaces are overlapped and fixed together. By this, light can be reflected on the inclined plane and optically coupled, and the overlapped area The connection strength can be strengthened because of the increase in the plane.

(Example) The gist of the present invention will be explained in detail below based on the example shown in the drawings.

As shown in the side sectional view of FIG. 1, the connection structure between the planar optical waveguide and the optical fiber includes a crystal substrate 1a having flat front and back surfaces;
For example, there is a planar optical waveguide substrate 1 having a planar optical waveguide 1b formed on one flat surface of a quartz glass substrate by a diffusion method or a deposition method, a crystal substrate 2a which also has flat surfaces on the front and back, and a quartz glass substrate formed by an etching/notching method. An embedding groove 2a-1 is formed by the following steps, and the optical fiber \2b is fixedly embedded in the optical fiber \holding substrate 2 with an adhesive (as shown in the figure). In addition, 1b
-1, 1b-2 are the core and cladding of the planar optical waveguide 1b,
2b-L2b-2 is the core and cladding of the optical fiber 2b.

The planar optical waveguide substrate 1 and the optical fiber holding substrate 2 each have side end surfaces with the same angle, for example, 45° slopes 1c and 2c, so that the end surface of the planar optical waveguide 1b is exposed to the slope 1c, and the end surface of the optical fiber 2b is exposed to the slope Keep it away from 2C and do not expose it.

The planar optical waveguide substrate 1 and the optical fiber holding substrate 2 have an inclined surface 1c.
, 2c are made to face each other, and their flat surfaces are overlapped so that the light travels in the direction of the arrow and is optically coupled, and are fixed with an optical adhesive (the path shown in the figure).

In this embodiment, in order to improve the optical coupling efficiency, a flat lens 3, that is, a grating lens (diffraction grating) for converging light, is attached to the slope 2C of the optical fiber holding substrate 2 as shown in the figure. (Note that since this plane lens 3 only needs to be provided on the optical coupling path, it may be attached to at least the slope 1c or 2c, or the overlapping surface 12d of the plane optical waveguide substrate 1 and the optical fiber holding substrate 2. ) The planar optical waveguide substrate and optical fiber holding board described above may be manufactured individually, but in order to improve the coupling accuracy,
In this embodiment, it is manufactured as follows. That is, as shown in the perspective view of FIG. 2, a planar optical waveguide substrate 1, i.e., 1'' and an optical fiber holding substrate 2, i.e., 2'' are manufactured from the same crystal substrate (quartz glass substrate) 11. As shown in the oblique view in the figure, before cutting and separating the planar optical waveguide substrate 1'' and the optical fiber holding substrate 2'', an inclined surface 1c that is perpendicular to the direction of propagation of light and at a predetermined angle (for example, 45') with respect to the flat surface is formed. .

After forming 2c in common, cut line A along the traveling direction of light.
- Cut at A and divide into two pieces.

Further, another embodiment of the connection between the planar optical waveguide substrate and the optical fiber holding substrate is shown in the side view of FIG. 4. That is, in contrast to FIG. 1, where the slopes 1c and 2c face each other in parallel and combine the light traveling direction in the forward direction, FIG.
'C are opposed so that they intersect, and the light is coupled in opposite directions. (Also, in this example, the plane lens may be attached to the slope or the overlapping part as in FIG. 1.) In this way, the optical fiber holding substrate temporarily holds the optical fiber firmly on the crystal substrate. This allows the optical fiber itself to be firmly held. By making the side end surfaces of the optical fiber holding substrate and the planar optical waveguide substrate sloped, and connecting the sloped surfaces facing each other, the overlapping area can be made much larger than in the past.
The connection strength can be strengthened compared to the conventional method.

Furthermore, in the other embodiment shown in FIG. 4, the overlapping area can be made much larger than that in FIG. 1, so that the connection strength can be further strengthened.

Furthermore, in any of the embodiments, by inserting a plane lens into the optical coupling path, light can be focused and efficient optical coupling can be performed.

〔Effect of the invention〕

As described in detail above, according to the present invention, the connection strength can be strengthened, so that a highly reliable optical coupling device can be provided, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an embodiment according to the present invention, FIG. 2 is a perspective view of a shared crystal substrate, FIG. 3 is a perspective view of FIG. FIG. 5 is a perspective view of the prior art. In the figure, 1 is a planar optical waveguide substrate, 2 is an optical fiber holding substrate, 1a, 2a, 11 is a crystal substrate (quartz glass substrate), 1b
2b is a planar optical waveguide, 2b is an optical fiber, 1 c + 2c + 1°c + 2°C is a slope, 3 is a flat lens (grating lens), and 12d is an overlapping surface. 5th evil

Claims (1)

[Scope of Claims] [1] A planar optical waveguide substrate (1a) having a planar optical waveguide (1b) on one flat surface of a crystal substrate (1a) having flat front and back surfaces.
) and an optical fiber holding substrate (2) in which an optical fiber (2b) is embedded in a crystal substrate (2a) having flat front and back surfaces, and the side of the planar optical waveguide substrate (1) and the optical fiber holding substrate (2). The planar optical waveguide substrate (1) and the optical fiber holding substrate (2) are arranged so that the end surfaces thereof are inclined planes (1c, 2c) having the same angle, and the inclined planes (1c, 2c) face each other for optical coupling.
) A connection structure between a planar optical waveguide and an optical fiber, characterized in that the flat surfaces of the two are overlapped and fixed with an optical adhesive. [2] The slopes (1c, 2c) according to claim 1 are slopes formed by forming the planar optical waveguide and the buried optical fiber on the same crystal substrate (11) and cutting the side end face of the crystal substrate (11) diagonally. (1'c, 2'c) A connection structure between a planar optical waveguide and an optical fiber. [3] At least one of the slopes (1c
or 2c) or a connection structure between a planar optical waveguide and an optical fiber, characterized in that a planar lens (3) is attached to the overlapping portion (12d).