JPH01156707A - Optical coupler for laser diode - Google Patents

Abstract

PURPOSE:To oscillate a laser diode stably by inserting a specific shield plate so that the axially symmetrical part of a light transmission part becomes the shield part about the center axis of an optical path. CONSTITUTION:The transmission part 7 and shield part 8 are formed in the optical path consisting of the laser diode LD 1, a rod lens 2, and an optical fiber 3. Then, the shield plate 6 is inserted into part of the optical path so that the axially symmetrical part of the transmission part 7 becomes the shield part 8 about the center axis of the optical path without fail. Consequently, a half of the light beam from the LD 1 which is not cut off is converged by a lens 2 and made incident on the optical fiber 3 and several % of the light is reflected by a fiber end surface to return to the lens 2, but cut off by the shield plate 6. Consequently, no reflected light returns to the LD 2, so the oscillation is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical coupler for a laser diode in which a laser diode and an optical fiber are optically coupled.

[Conventional technology]

Figure 6 shows a conventional optical coupler for laser diodes (LD
FIG.

In the figure, (l) is a laser diode (hereinafter referred to as LD), 12+ is a rod lens (square gradient index lens) for condensing the light emitted from the LD +11, +31 is an optical fiber, (4) is ray 1, and 151 is ray 2.

The light emitted from the LD (11) is focused by the rod lens (2) and enters the optical fiber (3).
The light is ray 1141. It is reflected from the end face of the optical fiber (3) like ray 2 (5) and returns to LD +11.

[Problem that the invention seeks to solve]

The conventional optical coupler for LD as described above is
The light emitted from L is condensed by a rod lens (2) and enters an optical fiber (3). However, a few percent of the light is reflected from the end face of the optical fiber (3) like ray 1 (41, ray 2 (5)) and returns to the LD ill, making the oscillation of the LD ill unstable. there were.

This invention was made to solve these problems, and its purpose is to prevent the light reflected from the end face of the optical fiber from returning to the LD, thereby stabilizing the oscillation of the LD.

[Means for solving problems]

In the optical coupler for LD according to the present invention, a transmitting part and a shielding part are formed in an optical path formed by the LD, a lens, and an optical fiber, and a part that is axially symmetrical to the transmitting part with respect to the central axis of the optical path is always provided. A shielding plate is inserted into a part of the optical path so as to serve as the above-mentioned shielding part, and an optical coupler for LD is constructed.

[Effect]

In this invention, a transmitting part and a shielding part are formed in the optical path formed by the LD, the lens, and the optical fiber, and the part axially symmetrical to the transmitting part with respect to the central axis of the optical path always becomes the shielding part. Since a shield plate is inserted in a part of the optical path, the light reflected from the end face of the optical fiber does not return to the LD.

〔Example〕

FIG. 1 is a sectional view of an optical coupler for LD showing one embodiment of the present invention.

In the figure, (1) is LD, +21 is the above LD +1
A rod lens for condensing the light emitted from 1.
(3) is an optical fiber, (4) is a light beam 1. +51 is ray 2
．． It is a +61 shielding board.

Approximately half of the light emitted from the LD [11 is blocked by the shielding plate (6), and light rays such as ray 1 (4) are blocked.

Approximately half of the light that is not blocked is collected by the rod lens (2) and enters the optical fiber (3). At this time, several percent of the light is reflected by the end face of the optical fiber [3] like ray 2 (5) and returns to the rod lens (2), but is blocked by the shielding plate (6).

FIG. 2 is a sectional view of an optical coupler for LD showing another embodiment of the present invention.

In the figure, the installation of the shielding plate (6) is the same as that of the LD optical coupler shown in FIG. 1 except for the position.

The light emitted from the LD ill is focused by the rod lens (2), and about half is blocked by the shielding plate (6), resulting in light beam 11.
Light m#is cut off like 4+. Approximately half of the light that is not blocked enters the optical fiber (3). At this time, several percent of the light is reflected by the end face of the optical fiber (3) like ray 2 (5), but is blocked by the shielding plate (6).

FIGS. 3, 4 and 5 are cross-sectional views showing embodiments of a transparent part and a transparent part, respectively, according to the present invention.

In the figure, (7) is a transparent part, and t8) is a Tfia side part.

The optical coupler for LD of this invention has a transmitting part (7) and a shielding part (8) formed in the optical path formed by the LD (1), the rod lens (21, the optical fiber (3), and the trap), and the optical path is By completely inserting the shielding plate (6) in a part of the optical path so that the part that is axially symmetrical to the transmitting part (7) with respect to the central axis of the optical fiber becomes the shielding part (8), the light reflected by the end face of the optical fiber can be prevented. This is to avoid returning to LE full.

〔Effect of the invention〕

As explained above, this invention prevents the light reflected from the end face of the single fiber from returning to the LD, so that the light emitted from the LD is reduced.
It can be made stable.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an optical coupler for LD showing one embodiment of the present invention, and FIGS. 3, 4, and 5 are embodiments of the transmitting part and connecting part of the present invention. FIG. 6 is a cross-sectional view showing a conventional optical coupler for LD. In the figure, (1) is the LD, +21 is the rod lens,
(3) is an optical fiber, (4) is a shielding plate for light rays 1, 151 and 2, 161, C7) is a transmitting part, and +81 is a shielding part. Note that the same or corresponding parts in FIG. 9 are designated by the same reference numerals.

Claims (1)

[Claims] In an optical coupler for a laser diode, which is composed of a laser diode, one or more lenses, and an optical fiber whose incident end face is substantially perpendicular, the light beam passes through the optical path formed by the laser diode, the lens, and the optical fiber. one or more shields that absorb, reflect, or scatter light in a part of the optical path so that a portion and a shielding portion are formed, and a portion that is axially symmetrical with the transmitting portion with respect to the central axis of the optical path becomes the shielding portion; An optical coupler for a laser diode characterized by inserting a plate.