JPS6125235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical coupling, and in particular, it is an object of the present invention to provide a method for coupling a semiconductor laser and an optical fiber, by which stable light emission operation of the semiconductor laser can be obtained.

A conventional method of coupling a semiconductor laser and an optical fiber is shown in FIG. Light 3 emitted from the light emitting surface 2 of the semiconductor laser 1 enters the input end surface 5 of the optical fiber 4 . At this time, the proportion of light that enters the optical fiber 4 out of the light emitted from the semiconductor laser 1, that is, the coupling efficiency, is mainly determined by the numerical aperture (N.
A.) and the emission distribution of the semiconductor laser. By the way, when the light 3 emitted from the semiconductor laser 1 enters the optical fiber 4, a part of the light is reflected by the entrance end face 5 and returns to the light emitting face 2 as reflected light 6.
Now, if this coupling efficiency is small, the reflected light 6 can also be ignored, but if the coupling efficiency is large, the proportion of the reflected light 6 that returns to the light emitting surface 2 will also increase, and as a result,
This has the drawback that non-negligible noise appears in the output light of the semiconductor laser, making the light emitting operation unstable.

The present invention provides a method for coupling a semiconductor laser and an optical fiber, which solves the above-mentioned drawbacks, and the configuration of one embodiment thereof is shown in FIG. In the following description, the same numbers shown in the drawings indicate the same parts.

In FIG. 2, 1 is a striped semiconductor laser, 2 is a light emitting surface, 7 is a bonding surface, 8 is a bonding plane including the bonding surface, 10 is the emission distribution of the semiconductor laser 1, 1
1 is a base line which is a straight line perpendicular to the light emitting surface 2 and is located in the bonding plane 8, which is set at the center of the light emitting surface 2; 4 is an optical fiber;
Reference numeral 12 denotes an optical fiber axis which is inclined with respect to the base line 11, and 9 is an incident end face which is inclined with respect to the optical fiber axis 12. Here, the optical fiber 4 is arranged with respect to the semiconductor laser 1 in the following relationship. That is, the long axis 13 of the oblique incident end surface 9 is on the bonding plane 8 and the short axis 14 is perpendicular to the bonding plane 8, and the light on the base line emitted from the semiconductor laser 1 is The optical fiber axis 12 is arranged at an angle with respect to the base line 11 so that after entering the end face 9 and being refracted, the optical fiber advances within the optical fiber 4 along the optical fiber axis 12.

FIGS. 3 and 4 show the main parts of the above configuration, and will be further explained using these. FIG. 3 shows the semiconductor laser 1 and the optical fiber 4 on the bonding plane 8 as seen from direction A. Here, 20 is a core part and 21 is a clad part. Since the entrance end surface 9 oblique to the optical fiber axis 12 is also arranged obliquely to the base line 11, the light 15, 16 emitted from the light emitting surface 2 at an angle that allows it to enter the optical fiber 4.
Of these, the lights 17 and 18 reflected by the incident end surface 9 do not return to the light emitting surface 2 again. Light 19 that is not reflected at the input end face 9 is refracted at the input end face 9 and enters the optical fiber 4 . At this time, in order to make most of the light emitted from the light emitting surface 2 enter the optical fiber 4, the light 1 that is incident on the incident end surface 9 along the base line 11 is
5 is refracted, the optical fiber axis 12 is aligned with the base line 1 so that (incident light 19) travels in line with the optical fiber axis.
It is tilted against 1.

FIG. 4 is a view of the optical fiber end face 9 viewed from the rear side (direction B) of the light emitting surface 2. Here, 10 indicates a typical emission distribution of the semiconductor laser 1. Generally, the emission angle of a striped semiconductor laser is 8
Since it is small at the top and large in the direction perpendicular to the junction plane 8, the emission distribution 10 has an elliptical shape. By the way, as described in the explanation of FIG. 3, when the optical fiber axis 12 is tilted with respect to the base line 11, the long axis 13 of the input end face 9 is placed on the bonding plane 8, and the short axis 14 is placed on the bonding plane 8. When the optical fiber axis 12 is arranged perpendicularly and tilted with respect to the base line 11 on the bonding plane 8, the shape of the end face of the optical fiber as seen from the light emitting surface becomes an ellipse, as can be seen from FIG. show. Therefore, since the shape of the light emission distribution 10 can be almost matched, there is almost no loss in coupling efficiency as described above.

According to this embodiment, the optical fiber end face 9 is made oblique to the optical fiber axis 12 and the base line 11, and the light incident on the incident end face 9 along the base line 11 is refracted and then refracted along the optical fiber axis 12. Further, the shape of the light emission distribution 10 of the semiconductor laser 1 and the incident end face 9 of the optical fiber viewed from the light emitting surface 2 are explained.
The optical fiber 4 is arranged so that the shape of the optical fiber 4 almost matches the shape of the
Especially in the method of coupling a striped semiconductor laser and an optical fiber, (i) the reflected light at the input end face 9 of the optical fiber does not return to the light emitting surface 2; There is little noise in the output light and stable operation is achieved.

(ii) In accordance with the emission distribution 10 of the semiconductor laser 1,
By arranging the optical fiber 4, there is almost no loss in coupling efficiency.

It has this excellent effect.

As described above, the present invention provides an industrially excellent coupling that dramatically reduces noise in the output light of the semiconductor laser and stabilizes the light emission operation without impairing the coupling efficiency when coupling a semiconductor laser and an optical fiber. It provides a method.

[Brief explanation of the drawing]

Fig. 1 is a perspective view illustrating a conventional coupling method, Fig. 2 is a perspective view illustrating an embodiment of the coupling method of the present invention, and Fig. 3 is a top view illustrating main parts of the present embodiment.
FIG. 4 is a front view illustrating the main parts of this embodiment. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Light emitting surface, 4... Optical fiber, 7... Bonding surface, 8... Bonding plane, 9...
...Incidence end face, 11...Base line, 12...Optical fiber axis, 13...Long axis of incidence end face, 14...Short axis of incidence end face, 15...Light perpendicular to light emitting surface, 19...Optical fiber axis Light traveling along.

Claims (1)

[Claims] 1. The input end face of the optical fiber coupled to the light emitting surface of the semiconductor laser is oblique to the axis of the optical fiber, and the long axis of the input end face is in the same plane as the bonding surface of the semiconductor laser. and arranged so that the minor axis of the incident end surface is perpendicular to the bonding surface,
A method for coupling a semiconductor laser and an optical fiber, characterized in that the axis of the optical fiber is tilted on the same plane as the bonding surface with respect to a direction perpendicular to the light emitting surface of the semiconductor laser. 2. The optical fiber axis is arranged such that light emitted from the center of the light emitting surface of the semiconductor laser and perpendicular to the light emitting surface, which enters from the oblique entrance end face, travels within the optical fiber almost along the optical fiber axis. 2. The method of coupling a semiconductor laser and an optical fiber according to claim 1, wherein the optical fiber axis is tilted with respect to the direction of light perpendicular to the light emitting surface.