JP2782736B2 - Optical fiber fixing structure of laser diode module - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical fiber fixing structure for a laser diode module.

[Conventional technology]

Conventionally, in this type of laser diode module, after adjusting the optical axis in three directions of X, Y, and Z, the end portion of the optical fiber is Sn-Pb soldered to a cylindrical bearing portion attached to a beam emission port of the module body. It is fixed or welded and fixed with a YAG laser via a ring-shaped spacer.

FIG. 3 is a cross-sectional view of an optical fiber fixing section for explaining an example of the related art.

As shown in FIG. 3, the fixed portion of the optical fiber is a spring formed of a metal pipe covered with a jacket 5a covering the optical fiber 5 in a cylindrical bearing portion 4 of the laser diode module. Is fixed by welding. The cylindrical bearing portion 4 and the spacer 7 are fixed at a welded portion 10a, and the metal pipe 5b of the optical fiber 6 is one of 10b when viewed in the axial direction of the optical fiber.
It is fixed at several places (however, several places on the circumference).

[Problems to be solved by the invention]

The above-described conventional optical fiber fixing structure has a drawback that the light output from the optical fiber tends to fluctuate in a temperature cycle test or a high-temperature storage test.

In other words, in a module in which a laser diode element and an SMF are optically coupled, the core diameter of the SMF is very small, about 10 μm. Occurs. However, in the Pb-Sn solder fixing structure, the positional displacement of the fiber is caused by the creep phenomenon of the solder caused by the presence of the stress. In addition, in the fixing structure in which the YAG laser welding is performed via a ring-shaped spacer, the positional displacement due to creep is extremely small as compared with the case where solder is used, and there is no problem, but the welding is performed on the circumference of the end of the ring-shaped spacer. When an external force is applied to the end of the optical fiber in the X, Y or Z directions, stress concentrates on the welded portion and deformation of the welded portion occurs, so that the position displacement or the angular displacement is caused. There is a drawback that the fiber light output is likely to fluctuate as a result.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber fixing structure of a laser diode module which does not cause displacement of a fiber position against a temperature cycle test, a high temperature storage test, and the action of an external force.

[Means for solving the problem]

An optical fiber fixing structure of a laser diode module according to the present invention includes an optical fiber inserted into a cylindrical bearing portion of a module main body, a laser diode, and a lens system that causes a light beam emitted from the laser diode to enter the optical fiber. In the laser diode module, a ring-shaped spacer including a flange portion for fixing to the cylindrical bearing portion and a cylindrical portion formed with a plurality of holes following the flange portion along the optical axis direction is provided. The plurality of holes formed in the cylindrical portion of the ring-shaped spacer and the end portion of the cylindrical portion are joined and held to the end portion of the optical fiber.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an optical fiber fixing portion of a laser diode module for explaining an embodiment of the present invention.

As shown in FIG. 1, the laser diode element 1 and the gradient index rod lens 2 are mounted on a metal substrate 8 with their optical axes aligned. The metal substrate 8 is mounted on a dual in-line type package 3 via an electronic cooler (Peltier) 9, and the beam exit 3 a of the package 3 is provided.
Is mounted with a cylindrical bearing portion 4. Bearing part 4
Is designed to be substantially coincident with the optical axis of the laser diode element 1 and the rod lens 2, and the optical fiber 6 having the optical fiber 5 is fixed by a ring-shaped spacer 7.

 FIG. 2 is an enlarged sectional view of a portion A shown in FIG.

As shown in FIG. 2, the optical fiber 6 has an optical fiber 5 at the center, the outer periphery of the optical fiber 5 is covered with a jacket 5a, and the terminal portion is covered with a metal pipe 5b. The ring-shaped spacer 7 for supporting the optical fiber 6 coaxially with the light beam is provided with a plurality of holes in a cylindrical portion into which the optical fiber 5 is fitted.

In such an optical fiber fixing structure, first, the laser diode element 1 is oscillated, the light beam is made incident on the fiber end portion, and the position where the incident light output is maximized is determined. The optical fiber 6 is held by a chuck jig in a state where the end of the fiber 6 is optically coupled to the end. Next, the flange portion of the ring-shaped spacer 7 inserted and fitted to the end of the optical fiber 6 with high precision is welded to the bearing portion 4. The cylindrical end and hole of the spacer 7 are connected to the metal pipe 5 b of the optical fiber 6. Is fixed by welding with a YAG laser. As a result, when viewed in the axial direction of the fiber, it is fixed at three different positions from the welding points 10a, 10b, 10c.

With such a fixing structure, the welded fixing portion between the metal pipe 5b of the optical fiber 6 and the ring-shaped spacer 7 is supported at two points of the welded portions 10b and 10c when an external force in the X, Y or Z directions acts. In other words, a stable optical coupling state with respect to the position and the angular displacement can be obtained.

〔The invention's effect〕

As described above, the optical fiber fixing structure of the present invention has a structure in which a ring-shaped spacer is attached to a cylindrical bearing portion, and the ends of the optical fiber are bonded and maintained at different positions in the optical axis direction of the spacer, thereby preventing external force. Thus, there is an effect that a laser diode module having no fluctuation in fiber output can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical fiber fixing portion of a laser diode module for explaining an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a portion A shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view of an optical fiber fixing unit for explaining the following. DESCRIPTION OF SYMBOLS 1 ... Laser diode element, 2 ... Gradient index rod lens, 3 ... Module package, 4 ... Cylindrical bearing part of module package, 5 ... Optical fiber strand, 6 ... Optical fiber, 7 ... Ring-shaped spacer.

Claims (1)

(57) [Claims] 1. A laser diode module comprising: an optical fiber inserted into a cylindrical bearing portion of a module body; a laser diode; and a lens system for causing a light beam emitted from the laser diode to enter the optical fiber. A ring-shaped spacer having a flange portion for fixing to a bearing portion and a cylindrical portion following the flange portion along the optical axis direction and having a plurality of holes formed therein, wherein the cylindrical portion of the ring-shaped spacer is provided; An optical fiber fixing structure for a laser diode module, wherein end portions of the optical fiber are joined and held at end positions of the plurality of holes and the cylindrical portion.