JPH04223412A - Receptacle-type semiconductor laser module - Google Patents

Abstract

PURPOSE:To provide a receptacle-type semiconductor laser module capable of controlling the reflected light at the end face of an optical fiber without reducing the optical coupling efficiency with a semiconductor laser. CONSTITUTION:A glass rod 3, for example, is provided in the receptacle-type semiconductor laser module. An antireflection film is formed on the face A of the rod 3, and the face B is spherically ground. The face B of the rod 3 is brought into contact with a ferrule 4 to be inserted, hence there is not air layer between the end face of the ferrule 4 and the face B of the rod 3, and the return of the reflected light to a semiconductor laser 1 which was conventionally caused by the refractive index difference between the air and the optical fiber is controlled at the end face of an optical fiber.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receptacle-type semiconductor laser module used in optical communications and which can be freely attached to and detached from an optical fiber ferrule.

0002

2. Description of the Related Art A conventional receptacle type semiconductor laser module is shown in FIG. In FIG. 1, 1 is a semiconductor laser, and 2 is an optical lens 2 that focuses laser light emitted from the semiconductor laser 1. In FIG. 4 is an optical fiber ferrule (hereinafter referred to as ferrule) inserted into this receptacle type semiconductor laser module. 4a is an optical fiber held by this ferrule 4, into which laser light from the semiconductor laser 1 is incident via the optical lens 2. At this time, it is necessary to position the ferrule in order to obtain higher optical coupling at the end face of the optical fiber 4a. Furthermore, in a receptacle-type semiconductor laser module, it is necessary to allow the ferrule to be attached and detached as many times as desired. Therefore, there is a mechanism in the module that allows the ferrule to be re-inserted in the same position once removed. 5 is a stopper provided for positioning the ferrule 4. This stopper 5 allows the insertion position of the ferrule 4 to be determined correctly, and highly efficient optical coupling can be obtained on the end face of the optical fiber 4a.

However, in the above structure,
Since the laser beam after passing through the optical lens 2 is focused on the core of the optical fiber 4a of the ferrule 4 through space, the laser beam is focused at the end face of the optical fiber 4a due to the difference in refractive index between the air and the fiber core. There was a problem in that the reflected light returned to the end face of the semiconductor laser 1 again, making the operation of the semiconductor laser 1 unstable.

0004

[Problems to be Solved by the Invention] As mentioned above, in conventional receptacle-type semiconductor laser modules, the efficiency of optical coupling with the semiconductor laser can be increased by positioning the ferrule, but There is a problem in that the light returns to the end face of the semiconductor laser again, making the operation of the semiconductor laser unstable.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a receptacle-type semiconductor laser module that suppresses reflected light at the end face of an optical fiber without reducing the optical coupling efficiency with the semiconductor laser. With the goal. [Structure of the invention]

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention houses a semiconductor laser and an optical lens for condensing laser light emitted from the semiconductor laser at a predetermined position. In a receptacle-type semiconductor laser module into which a ferrule holding an optical fiber can be inserted, the ferrule is positioned by contacting an end face of the ferrule inserted from the outside, and the surface in contact with the ferrule is polished to a spherical surface. It is composed of a rod made of optical material.

[0007]

[Operation] In the receptacle type semiconductor laser module having the above configuration, the rod is in contact with the end face of the ferrule, and the air layer that conventionally existed between them is eliminated.
Reflected return light caused by the difference in refractive index is suppressed. Furthermore, the rod also acts as a positioner for the ferrule, and it is possible to eliminate a factor causing instability in the operation of the semiconductor laser without reducing the optical coupling efficiency.

[0008]

Embodiment FIG. 1 is a diagram showing a receptacle-type semiconductor laser module which is an embodiment of the present invention. Similar to FIG. 2, it is a diagram in which a ferrule 4 holding an optical fiber 4a is inserted. The same parts as in FIG. 2 are given the same reference numerals and detailed explanations will be omitted.

The difference between FIG. 1 and FIG. 2 is that a rod 3 is provided. The rod 3 is made of an optical material such as glass, and has a surface (A) adjacent to the optical lens 2.
The ferrule 4 side surface (B surface) is spherically polished. This rod 3 is fixed at a position where, for example, the laser beam from the semiconductor laser 1 is focused on the B surface of the rod 3, and the ferrule 4 is inserted until its tip surface contacts the B surface of the rod 3. Ru. Therefore, the B side of the rod 3 is connected to the optical fiber 4a held by the ferrule 4 without any gap, and there is no air layer between the two. In particular, since the end face of the ferrule 4 is polished to a spherical surface like the rod 3, air is less likely to be present between the contacting surfaces compared to a case where both are flat. Furthermore, since the refractive index of the rod is sufficiently close to the refractive index of the optical fiber compared to the refractive index of air, the refractive index of the semiconductor laser, which was previously caused by the difference in refractive index between the air layer and the optical fiber, can be reduced. Reflected return light can be sufficiently suppressed.

Furthermore, since the rod 3 also acts as a positioner for the ferrule 4, if the B surface of the rod 3 is used as the focal point of the laser beam as described above, the optical coupling efficiency with the semiconductor laser will not be reduced. Reflected light at the end face of the optical fiber can be suppressed. Note that the present invention is not limited to the above embodiments. For example, a condensing lens for condensing laser light may be an aspherical lens in order to obtain high optical coupling efficiency. Further, the material of the rod is not limited to glass material, and may be any optical material that transmits light of a necessary wavelength. Furthermore, the coupling efficiency can be further improved by using a converging rod lens or a double-sided spherical lens as the rod, and by forming the coupling optical system into a two-group lens system.

[0011]

Effects of the Invention As detailed above, the receptacle type semiconductor laser module of the present invention is equipped with a rod, and when the rod comes into contact with the optical fiber ferrule to be inserted, the air gap that conventionally occurs is eliminated. There is no difference in refractive index between the optical fiber and the optical fiber, and this rod also acts as a positioner for the optical fiber ferrule, so it is possible to sufficiently suppress reflected light from the optical fiber end face without reducing the optical coupling efficiency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a receptacle-type semiconductor laser module according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional receptacle-type semiconductor laser module.

[Explanation of symbols]

1 Semiconductor laser 2 Optical lens 3 Rod 4 Ferrule 4a Optical fiber

Claims (4)

[Claims] 1. A receptacle-type semiconductor laser module that houses a semiconductor laser and an optical lens that focuses laser light emitted from the semiconductor laser at a predetermined position, and into which an optical fiber ferrule can be inserted from the outside. The optical fiber ferrule is positioned by contacting with the end face of the optical fiber ferrule, and the rod is made of an optical material whose surface in contact with the optical fiber ferrule is polished to a spherical surface. Receptacle type semiconductor laser module. 2. The receptacle-type semiconductor laser module according to claim 1, wherein the optical lens is an aspherical lens. 3. The receptacle-type semiconductor laser module according to claim 1, wherein the optical material forming the rod is glass. 4. The receptacle-type semiconductor laser module according to claim 1, wherein the rod is a rod lens.