JPH03155509A - Optical module - Google Patents

Abstract

PURPOSE:To obtain an optical module with low optically coupled loss and high productivity and reliability by arranging the tip plane at the optical device side of an optical fiber so as to be almost flush with the joining plane of an engaging ring and a package. CONSTITUTION:The tip plane 7a at the optical device side of the optical fiber 7 is arranged so as to be almost flush with the joining plane of the engaging ring 9 and the package 2. Since the deviation of an optical axis from the inclination of the optical fiber is nearly proportional to a distance between the joining plane of the optical fiber 7 with the package 2 and an optical fiber input terminal 7a, the deviation of the optical axis due to the inclination of the optical fiber can be almost neglected in such constitution. In such a way, it is possible to suppress the deterioration of coupling efficiency, and to attain the reduction of the assembling man-hours of the optical module and the improvement of the productivity and the reliability.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a transmitting/receiving module for optical communication.

[Conventional technology]

BACKGROUND OF THE INVENTION With the demand for higher speed and larger capacity of optical communication, there is a demand for higher performance and higher reliability of various optical modules such as light emitting and light receiving components, which are the constituent elements thereof. FIGS. 2(a) and 2(b) show an example of a communication semiconductor laser (LD) module. FIG. 2(a) is a top view, and FIG. 2(b) is a cross-sectional view taken along line BB'. The box-shaped package 2 is composed of a plurality of in-line leads 1 and a metal rod 3. In the metal rod 3, the central notch has an LD mounted on a heat sink 5, a lens 4 is located in the hollow part 3a, and a metal (ferrule) is connected to the tip via a ring-shaped connecting member (slide ring) 9. It holds an optical fiber 7 coated with.

The tip 7a of the optical fiber 7 protrudes from the slide ring end face 9a and is located in the hollow portion 3a of the metal rod 3. Here, the emitted light from the LD 6 is magnified and imaged through the lens 4, and efficiently coupled to the optical fiber 7 whose end face is disposed at the image formation position. The optical fiber is first aligned in the optical axis direction (Z)
The slide ring 9 is fixed after alignment in the x and y directions.
It is held in the package by fixing the package 2 and the package 2. The fixing is YAG, which is considered to be highly reliable.
Laser spot welding and solder joining are commonly used.

[Problem to be solved by the invention]

As described above, the slide ring 9 and the optical fiber 7, and the slide ring 9 and the package 2 are bonded together by YAG laser welding or solder bonding. In the case of YAG laser welding, spot welding is performed at 3 or 6 points, but optical axis deviation (lateral deviation) within the joint surface due to power imbalance between multiple laser beams, area degree and parallelism of the joint surface The optical axis of the optical fiber may be tilted due to a malfunction or the like, and the optical coupling efficiency may deteriorate. Figures 3 (a) and (b) show the lateral deviation (Δy) and inclination (Δθ) of the optical axis of the optical fiber at the joint.
This shows an enlarged cross-section of the joint.

The amount of axis deviation Δy due to the optical axis inclination Δθ is proportional to the distance d between the joint 10 and the tip of the optical fiber. A similar problem occurs in solder joints due to non-uniformity in the amount of solder. In addition, changes over time and external forces may cause displacement in the bonded portion, deteriorating the optical coupling efficiency. To reduce this deviation, there are measures such as controlling component accuracy, carefully assembling, and using the module in an environment with small temperature changes, but considering manufacturing costs and user usage conditions, it is not necessary to take drastic measures. It's not a solution.

An object of the present invention is to solve the above-mentioned problems and provide an optical module with low optical coupling loss, low cost, and high reliability.

[Means to solve the problem]

The present invention includes an optical element that is a light emitting or light receiving element installed in a package, a coupling lens placed in front of the optical element, and a cylindrical ferrule that is secured to the package through a fitted ring. , an optical module comprising an optical fiber whose distal end surface is located at the image formation position of the coupling lens, such that the distal end surface of the optical fiber on the optical element side is substantially flush with the joining surface between the fitting ring and the package. [Operation] In the optical module of the present invention, the optical module emits light so that the input end of the optical fiber protected by the ferrule is located at the joint surface between the optical fiber and the optical module package. , or a light receiving element,
A combination lens is placed. Since the deviation of the optical axis due to the tilt of the optical fiber is approximately compared to the distance between the joint surface of the optical fiber and the package and the input end of the optical fiber, in this configuration, the deviation of the optical axis due to the tilt of the optical fiber can be almost ignored.

Therefore, it is possible to eliminate one of the two main causes of optical axis deviation, optical fiber lateral deviation and optical fiber inclination, and to significantly suppress deterioration of coupling efficiency, reducing the number of assembly units, increasing productivity, and Improved reliability can be measured.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view of a module illustrating the present invention. The components are the same as those of the conventional example shown in FIG. 2, and the package 2 is composed of a plurality of in-line leads 1 and a metal rod 3. In the metal bar 3, the notch in the center is a heat sink 5.
A lens 4 is located in the center of the LD 6 mounted above, and an optical fiber 7 coated with metal (ferrule) is held at the tip via a slide ring 9. The tip 7a of the optical fiber 7 is located on the same plane as the end surface 9a of the slide ring 9. The emitted light from the LD 6 is imaged by the lens 4 in substantially the same plane as the joining surface of the package 2 and the slide ring 9, and is coupled to the optical fiber 7. First, alignment in the optical axis direction (Z) is performed to fix the optical fiber 7 and the slide ring 9, and then, after alignment in the x and y force directions, the slide ring 9 and the package 2 are fixed. Fixation is performed by spot welding using a YAG laser or soldering. The input end of the optical fiber 7 is located almost within the joint surface with the package, and even if the optical axis of the optical fiber is tilted due to external pressure or changes over time, the optical axis misalignment will occur between the fiber end surface and the joint surface between the package and the optical fiber, as described above. Since this is proportional to the distance, the optical axis deviation can be almost ignored in this configuration. Therefore, in addition to reducing coupling loss compared to the conventional configuration,
Significantly reduces adjustment man-hours and improves productivity and reliability.

In this embodiment, an LD with an optical element is shown, but the same applies to a PD. Further, although the imaging system is configured with one lens, it may be an imaging system with two or more lenses.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to realize an optical module with low optical coupling loss, high productivity, and high reliability.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2(a),
(b) is a configuration diagram of a conventional optical module, and Fig. 3 (a>,
(b) is a diagram showing the optical axis deviation of the optical fiber. 1・
...Lead, 2...Package, 3...Metal rod, 4
...Lens, 5...Heat sink, 6...Semiconductor laser, 7...Optical fiber 9...Slide ring, 10...Joint surface.

Claims (1)

[Claims] An optical element consisting of a light-emitting or light-receiving element installed in a package, a coupling lens placed in front of the optical element, and a cylindrical ferrule fixed to the package through a fitted ring are protected, and the tip surface is In an optical module comprising an optical fiber located at an image forming position of a coupling lens, the optical fiber is arranged so that its tip end face on the optical element side is substantially flush with the joining surface of the fitting ring and the package. An optical module characterized by: