JPH0510643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical terminal structure that is an optical coupling device used in optical communications and the like.

In optical communications using optical fibers, when a semiconductor laser is used as a light source, there is concern about oscillation if the light from the laser, which is an oscillator, is reflected back to the laser from the end face of the optical fiber. This may cause problems with qualitative or noise. Furthermore, an optical loss of about 4% occurs at the end face of the optical fiber. In order to prevent the above-mentioned problems, an anti-reflection film using an interference film is provided on the end face of the optical fiber.

[Conventional technology]

FIG. 2 is a diagram showing the terminal structure of an optical fiber having a conventional anti-reflection film. In the figure, 1 is an optical fiber, 2 is a resin coating that protects the optical fiber,
3 is a ceramic pipe, 4 is a metal pipe, 5 is a glass plate, and 6 is a non-reflective film.

As shown in the figure, in this conventional example, the end of the optical fiber is inserted and fixed into a ceramic pipe 3, the ceramic pipe 3 is further inserted and fixed into a metal pipe 4, and after polishing their end surfaces to be the same surface,
A glass plate 5 having a non-reflective film 6 is fixed with an optical adhesive.

The light transmitted to the optical fiber 1 enters the glass plate 5, passes through the non-reflection film 6, is emitted to the outside, and is optically coupled to a light receiving element or an optical circuit device. At this time, even though it is a non-reflective film, there is some light reflection. However, the light emitted from the optical fiber 1 has an aperture angle θ
Since the reflected light returns to the optical fiber 1, only a small portion of the reflected light returns to the optical fiber 1, and its influence on the light source is suppressed.

The above-mentioned optical fiber terminal portion is optically coupled to a light emitting element, a light receiving element, an optical circuit element, etc. (not shown) via a lens, and the metal pipe is fixed to the base of the device by performing optical axis alignment.

[Problem that the invention seeks to solve]

In the structure described above, since the glass plate 5 is adhesively fixed across both the ceramic pipe 3 and the metal pipe 4, which have different coefficients of thermal expansion, changes in the radial and axial directions occur due to changes in the environmental temperature. There was a problem that stress was generated and the glass plate 5 peeled off.

[Means for solving problems]

The present invention provides an optical fiber terminal structure that solves the above-mentioned problems, and the means thereof is such that the optical fiber terminal is inserted and fixed into a ceramic pipe, and the ceramic pipe is further inserted and fixed into a metal pipe, and the optical fiber terminal is inserted and fixed into a metal pipe. In an optical fiber terminal structure in which a non-reflective glass plate is attached to the tip surface of a ceramic pipe including the end surface, the tip surface of the ceramic pipe to which the optical fiber terminal is fixed is made to protrude beyond the tip surface of the metal pipe. This is accomplished by a fiber optic terminal structure.

[Effect]

In the above optical fiber terminal structure, the tip surface of the ceramic pipe to which the optical fiber terminal is fixed is made to protrude beyond the tip surface of the metal pipe, so that the glass plate with the anti-reflection film is not bonded to the metal pipe. Glued only to optical fibers and ceramic pipes. Therefore, since the glass and ceramic are bonded to each other with substantially the same coefficient of thermal expansion, the stress generated between them due to temperature changes is small, so that a situation such as separation of the glass plates does not occur.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a main part of an embodiment of the present invention as a sectional view. In this embodiment, as shown in the figure, the end of an optical fiber 10 is inserted and fixed into a ceramic pipe 11, and the ceramic pipe 11 is further inserted into a metal pipe 12, so that the ceramic pipe 11 After the ceramic pipe 11 and the optical fiber fixed to the pipe are fixed with their tip surfaces slightly protruding, the tip surfaces of the ceramic pipe 11 and the optical fiber fixed to the pipe are brought into alignment and polished.

Next, the finished ceramic pipe 1
A glass plate having a non-reflection film 13 is bonded to the tip surface of the optical fiber 10 and the glass plate 14 using an optical adhesive having the same refractive index as that of the glass plate 14.

In the figure, 15 is a resin coating for protecting the optical fiber, and 16 is a glass pipe for preventing the optical fiber from breaking.

In this embodiment configured as described above, the glass plate having the anti-reflection film 13 is bonded only to the ceramic pipe 11 and the optical fiber 10, so that the bonding is between glass and ceramic having approximately the same coefficient of thermal expansion. It is not affected by metal pipes, and the stress generated between them due to temperature changes is small. Therefore, the occurrence of troubles caused by peeling of the glass plate is eliminated.

Expansion and contraction due to temperature changes between the ceramic pipe 11 and the metal pipe 12 cause mutual movement in the radial and axial directions, but the end surface of the ceramic pipe 11 and the end surface of the metal pipe 12 are separated from each other. Therefore, the adhesive portion of the glass plate 14 is not affected. Furthermore, since a sufficient amount of adhesive is secured around the device, the adhesive strength is highly reliable.

The optical fiber end portion after being adhesively fixed is optically coupled to a light emitting element, a light receiving element, an optical circuit element, etc. (not shown) via an optical lens, but the optical axis is aligned and the metal pipe is fixed to the base of the device. use

〔Effect of the invention〕

As explained above, according to the present invention, the end surface of the ceramic pipe to which the end of the optical fiber is fixed is made to protrude beyond the end surface of the metal pipe, so that the adhesive part of the glass plate having the anti-reflection film can be attached to the optical fiber. Since there is only the end face of the and ceramic pipe, and the adhesive does not extend to the metal pipe like in the past,
This eliminates the possibility of the glass plate peeling off due to stress generated in the bonded area due to temperature changes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of an optical fiber terminal structure of the present invention, and FIG. 2 is a sectional view of a main part of a conventional optical fiber terminal structure. In the figure, 10 is an optical fiber, 11 is a ceramic pipe, 12 is a metal pipe, 13 is a non-reflective film, 14
15 represents a glass plate, 15 represents a resin coating, and 16 represents a glass pipe.

Claims (1)

[Claims] 1. In an optical fiber terminal structure in which an optical fiber terminal is inserted and fixed into a ceramic pipe, the ceramic pipe is further inserted and fixed into a metal pipe, and a non-reflective glass plate is attached to the tip surface of the ceramic pipe including the end surface of the optical fiber. An optical fiber terminal structure characterized in that the end surface of a ceramic pipe to which an optical fiber terminal is fixed is made to protrude beyond the end surface of a metal pipe.