JPS58190908A - Optical coupling device - Google Patents

Abstract

PURPOSE:To concentrate all light beams within a photodetecting angle and to improve the optical coupling efficiency, by facing the terminal of a large/small diameter of an optical fiber to the cavity terminal of a truncated cone within a connector. CONSTITUTION:A connector 2 contains a cavity 5 of a truncated cone having the upper bottom of approximately same diameter as that of a light emitting part 3 of a light emitting element 1 and a lower bottom of approximately same diameter as that of an optical fiber 4. A meat., etc. is vapor-deposited to the inner wall 6 in the side circumference of the cavity 5 in order to use the wall 6 as a reflector. The element 1 is mounted so that the upper surface of the part 3 is positioned at the upper bottom of the cavity 5. The end face of the fiber 4 is polished as conventional. It is not always required to use only a turncated cone for the cavity 5, and a curved wall 6 is also available.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical coupling structure for optically coupling a light source made of a light emitting element or the like to a large diameter optical fiber.

Conventionally, when optically coupling a light source and an optical fiber, the first
As shown in the figure, the light emitting element 1 is mounted on the connector 2, and the optical fiber 4 is connected to the light emitting part 3 of the light emitting element 1.
However, with this configuration, high coupling efficiency cannot be obtained, and as shown in FIG. 2, the coupling efficiency is low when one end of the optical fiber 4 is processed into a tapered shape. However, such machining requires extremely high precision and has the disadvantage that machining is extremely difficult.

The present invention has been made in view of the above drawbacks, and an object of the present invention is to provide an optical coupling structure that can improve the optical coupling efficiency between a light source and a large-diameter optical fiber.

Hereinafter, the present invention will be explained based on examples. FIG. 3 is a sectional view showing an embodiment of the present invention, in which inside the connector 2,
A truncated cone-shaped cavity 5 whose upper base has approximately the same diameter as the light emitting part 3 of the light emitting element 1 and whose lower base has approximately the same diameter as the optical fiber 4 is provided, and the lateral inner wall 6 of the cavity 5 is coated with metal or the like. The light emitting element 1 is mounted such that the top surface of the light emitting part 3 is located at the top of the cavity 5, and the optical fiber 4 is mounted at the bottom of the cavity 50. The end face is fixed in position. Note that the end face of the optical fiber 4 is polished as in the conventional case. Further, the shape of the cavity 5 is not limited to a truncated cone; for example, the side inner wall 6 may have a curved shape as shown in FIG.

In this way, since the cavity 5 having the reflecting mirror 6 is provided between the light emitting part 3 of the light emitting element 1 and the end face of the optical fiber 4, conventionally,
Light that cannot propagate within the optical fiber because it is outside the acceptance angle also enters within the acceptance angle, improving optical coupling efficiency.

Next, FIG. 5 shows a different embodiment of the present invention, in which the cavity 5 in the embodiment described above has a refractive index approximately equal to that of the optical fiber 4, such as polyester, epoxy, epoxy acrylate, etc. (about 1 .5), and the other configurations are the same.

With this configuration, it is possible to provide an optical coupling structure that can also improve the following drawbacks. That is, in the above-mentioned embodiment, since the inside of the reflecting mirror 6 is empty W45, the refractive index in the reflecting mirror 6 and the refractive index in the optical fiber 4 are different (the refractive index in the reflecting mirror 6 and that in the optical fiber 4 are ,
They are approximately 1 and 1.5, respectively. ), therefore, light is reflected and refracted at the interface 7 between the inside of the reflecting mirror 6 and the optical fiber 4, as shown by arrow lines in FIG. 6 (an enlarged view of the main part in FIG. 3). Then, the reflected light enters the light emitting unit 3 either directly or by being reflected by the reflecting mirror 6, and when an LD (laser diode) is used as the light emitting element l, the interface 7 between the inside of the reflecting mirror 6 and the optical fiber 4 There is a drawback that the oscillation inside the LD becomes extremely unstable due to the incidence of the light reflected by the optical fiber 4 in the cavity 5.
By filling the transparent resin 8 with a refractive index substantially equal to the refractive index of , reflection at the interface between the resin 8 and the optical fiber 4 is greatly reduced, and this drawback can be improved. or,
Filling the cavity 5 with the resin 8 also has the additional effect of preventing dust and dirt from adhering to the reflecting mirror 6 and the light emitting section 3 of the light emitting element 1.

As described above, the optical coupling structure according to the present invention is a substantially truncated cone whose upper base has approximately the same diameter as the light emitting part of the light source, whose lower base has approximately the same diameter as the optical fiber diameter, and whose side inner wall is a mirror surface. A shaped cavity is provided inside the connector, and the top surface of the light emitting part is positioned at the top of the cavity, and the end face of the optical fiber is positioned at the bottom of the cavity. The light that could not propagate also enters the acceptance angle,
Therefore, optical coupling efficiency can be increased.

[Brief explanation of the drawing]

1 and 2 are sectional views of a conventional example, FIG. 3 is a sectional view of an embodiment of the present invention, FIGS. 4 and 5 are sectional views of different embodiments, and FIG. 6 is a sectional view of a conventional example. It is an enlarged view of the main part of FIG. 3. Patent Applicant Matsushita Electric Works Co., Ltd. Agent Patent Attorney Toshimaru Takemoto (and 2 others) 5-32 Figure 1 3'-2 Figure 3 Figure 4 Figure 6 Procedural Amendment (1982) August 1st, Mr. Commissioner of the Japan Patent Office ■, Indication of the case Patent application No. 073645 of 1982, Name of the invention Optical coupling device 36 Amendment person Relationship with the case Patent applicant Address 1048 Kadoma, Kadoma City, Osaka Prefecture Address name (583) Matsushita Electric Works Co., Ltd. Representative Iku Kobayashi 4, agent address 1048-6 Kadoma, Kadoma City, Osaka Prefecture, subject of amendment 33-

Claims (1)

[Claims] (1) Provide inside the connector a generally truncated conical cavity whose upper base has approximately the same diameter as the light emitting part of the light source, whose lower base has approximately the same diameter as the optical fiber diameter, and whose side peripheral inner wall is mirror-finished; An optical coupling structure in which the upper surface of the light emitting part is positioned at the upper bottom of the cavity, and the end surface of the optical fiber is positioned at the lower bottom of the cavity.