JPH04168405A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To use only one kind of optical fiber to reduce a stock and shorten a constructing period by constituting a semiconductor laser device of optical fiber from a semiconductor laser, a lens, an optical fiber having the top obliquely polished and having a light attenuating plate thereon, and its parts. CONSTITUTION:The optical axis of a semiconductor laser 1 is fitted and fixed to a radiating plate 3 together with a lens 4 through a heat sink 2. The top end of an optical fiber 6 is obliquely polished at an angle possible to prevent the reflected light from returning to the semiconductor later and disturbing the oscillating mode. A light attenuating plate 5 is provided on the obliquely polished part. Thus, when a material the attenuating quantity of which is changed according to the range of a desired optical fiber output is prepared and adhered to the top end as occasion demands, the desired optical fiber output can be obtained. Therefore, one kind of optical fiber suffices, and a reduction in stock and the shortening of construction period can be attained. Further, as the obliquely polished optical fiber is used, the optical axis adjustment is simplified, allowing an improvement in stability of the fiber output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a so-called low output type semiconductor laser device with an optical fiber, in which the optical output is reduced to a predetermined value.

[Conventional technology]

Semiconductor lasers with an optical fiber output of 0.1 mW class are used for short-distance optical communications. In a normal optical coupling method, an optical fiber output of 1 mW class can be obtained, but methods are being used to obtain a lower optical fiber output by shifting the coupling adjustment from the optimum position or attenuating it. A conventional example is shown in FIG. Semiconductor laser 1 is heat sink 2
It is attached to the heat dissipation plate 3 via the lens 4, and is fixed with the optical axis aligned with the lens 4. Light beam 7 focused by a lens
The optical axis is adjusted so that the laser beam enters the optical fiber 6, and it is fixed to an envelope (not shown), forming an integrated module together with the semiconductor laser and lens. The tip of the optical fiber 6 has an obliquely polished finish that is tilted by an angle θ with respect to a plane perpendicular to the optical axis.In order to obtain the desired optical fiber output, the angle θ must be set to a predetermined value and the optical axis must be adjusted. Fine adjustments are made by moving it slightly from the optimal position before it is fixed to the package.

[Problem to be solved by the invention]

Since the desired value of the optical fiber output varies depending on the application, conventionally, several types of optical fibers with different oblique polishing angles θ have been prepared and used depending on the application. For this reason, there was a heavy burden on production management, such as keeping a large number of expensive optical fiber parts with obliquely polished finishes in stock. The present invention provides an optical fiber output adjustment method that uses one type of optical fiber and can be adapted to various uses.

[Means to solve the problem]

The semiconductor laser device with optical fiber of the present invention is composed of a semiconductor laser, a lens, an optical fiber whose tip is obliquely polished, and a package for optically aligning and fixing these components, and an optical attenuation plate is provided at the tip of the optical fiber. It is characterized by being glued.

The angle θ at the tip of the optical fiber is set to the angle required to prevent reflected light from returning to the semiconductor laser and disturbing the oscillation mode, and only one type is prepared. Prepare as many types of optical attenuation plates as necessary with different attenuation amounts depending on the range of desired optical fiber output, and glue the desired optical attenuation plate to the tip of the optical fiber as needed to achieve the desired result. of optical fiber output can be obtained.

〔Example〕 Next, the present invention will be explained based on examples.

FIG. 1 shows the configuration of the present invention, in which a semiconductor laser 1 and a lens 4 are fixed on a heat sink 3 via a heat sink 2 with their optical axes aligned. The tip of the optical fiber 6 is obliquely polished to θ=10°, and a light attenuation plate 5 is bonded to the tip.

FIG. 2 is an enlarged view of the tip of the optical fiber, in which the optical fiber wire 63 is covered with an inner glass tube 62 and further protected by a metal outer vibro 1. The tip of this fiber is obliquely polished, and before adjustment, an optical attenuation plate 51 having an amount of attenuation corresponding to the target optical fiber output value is adhered and used. The light attenuation plate has a thickness of 0.5 to 1. A glass filter with an attenuation of 2 to 10 times greater than On+a may be used. For adhesion, transparent epoxy resin gives good results.

FIG. 3 is an enlarged view of the tip of an optical fiber showing another embodiment of the present invention. The overall structure is the same as that shown in FIG. 1, or the light attenuation plate is replaced with one in which an attenuation film 53 is formed on the surface of a transparent plate 52. The transparent plate is easy to use because the glass plate has a good thermal expansion coefficient that matches that of the optical fiber. The attenuation film is formed by depositing or attaching a metal film onto the surface of the glass plate. A desired amount of attenuation is obtained by adjusting the film thickness. It is desirable to form a dielectric film on the surface of the film to provide an antireflection effect.

〔Effect of the invention〕

As described above, a small optical attenuation plate can be selected and used before adjustment, and only one type of expensive optical fiber is required, so there are great economic effects such as reduction of inventory and shortening of construction period. As a secondary effect, the use of optical fibers with a fixed angle θ of 5 simplifies the work of adjusting the optical axis, resulting in improved workability and improved stability of the optical fiber output.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a partially enlarged view showing the features of the present invention. FIG. 3 is an enlarged view of the tip of an optical fiber showing a second embodiment of the present invention. Figure 3 is a configuration diagram showing a conventional example. 1... Semiconductor laser, 2... Heat sink, 3...
・Heat sink, 4...Lens, 5...Light attenuation plate, 6...
- Optical fiber, 7... Light beam, 51... Light attenuation plate, 52... Transparent plate, 53... Attenuation film, 61...
Exterior pipe, 62...Interior glass tube, 63...Optical fiber wire.

Claims (1)

[Claims] A semiconductor laser device in which a semiconductor laser, a lens, and an optical fiber whose tip is obliquely polished are optically aligned and fixed and housed in a package, characterized in that an optical attenuation plate is bonded to the tip of the optical fiber. Semiconductor laser equipment.