JPS6076710A - Optical coupling device - Google Patents

Abstract

PURPOSE:To enable fixing of a light emitting element and a coupling element at <=2mum deviation from an optimum adjusting position by fitting loosely the cylindrical part of a holder to the groove part of a guide ring then fixing the guide ring and the holder by the fitted part thereof. CONSTITUTION:A semiconductor laser 1 is melt stuck and fixed via a heat sink 2 to a stem 3 and a guide ring 16 is hermetically fixed thereto. A groove-shaped ring 11 is formed to the ring 16 in such a way that the cylindrical part of a holder 15 fits loosely into said part. The light emitting pattern of a semiconductor laser 1 is monitored with an IR television camera or the like through a coupling element 4 fixed to the holder 15 and the positional relation of the stem 3 and the holder 15 is so adjusted as to maximize the coupling efficiency to a prescribed optical coupler. A solder material 17 is then thermally stuck to the holder 15 by a high frequency coil or the like installed around the holder, thereby fixing the holder.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a coupling device between an optical element for transmitting optical information and an optical 7-eyeper.

The development of low-loss optical fibers, coupled with the development of semiconductor lasers and light-emitting diodes using AlGaAs and InGaAsP as base materials, has significantly accelerated the commercialization of optical fiber transmission systems.

Optical 7 Eyebar communication system efficiently uses high-quality light beams emitted from semiconductor lasers and light-emitting diodes.
Developing methods for coupling to optical fibers is an important challenge. For this purpose, methods have been proposed, such as a method in which the tip of the optical fiber is rounded to have a lens effect, and a method in which a coupling element such as a ball lens or a cylindrical lens is placed between the light emitting element and the optical 7 eye bar. These coupling elements must be placed close to the light emitting element within a distance of several micrometers to several tens of micrometers, and various holding and fixing methods are employed. In order to use these coupling elements to obtain a high light coupling efficiency that matches the theoretical value, the position must be determined with extremely high precision.For example, when using a semiconductor laser that oscillates in a single mode, When coupling light into a single mode light 7 eyeper, in order to suppress the coupling efficiency drop to eldB, the coupling element must be adjusted to within about ±201 tm in the beam emission direction and within about ±2 μm in the plane perpendicular to the emission direction.・Must be fixed.

1iIAI coupling element!・Fixing work is usually done by powering a fixed light emitting element to emit light and monitoring this emitted beam with an infrared television or camera, or by attaching it to a removable adjustment jig while measuring the entire optical fiber output. The coupling element thus obtained is adjusted in the x, y, and z three-axis directions to determine the optimum position 1 to . After that, a method is adopted in which the metal members holding the light emitting element and the coupling element are fixed by means such as soldering or welding. At this time, the light emitting element of the semiconductor laser is
To prevent the reflective surface formed by cleavage and the exposed part of the p-n junction from becoming irritated by oxygen in the air, deteriorating operating characteristics and impairing reliability, do not expose the reflective surface to the exposed part of the p-n junction in an inert gas atmosphere such as nitrogen. There is peace of mind that it will stop. However, with the conventionally proposed method, the deviation from the optimal adjustment position was kept within a few μm when the light emitting element and coupling element were identified by soldering or welding.
Achieving an airtightness of less than 10-' atm*cc/see was extremely difficult and rare.

An object of the present invention was to solve the above-mentioned drawbacks, and the purpose of the present invention is to provide a coupling device for a light emitting element and an optical fiber, in which the light emitting element and the coupling element are deviated from the optimal adjustment position.
Can be identified at micrometers or less and at the same time 10-” atm
- It is an object of the present invention to provide a coupling device that realizes airtight sealing of cc/sec or less with good reproducibility.

According to this invention, a base for picking up an optical element, a holder for airtightly holding a coupling element for optically coupling the optical element e,
In this optical coupling device, which consists of a base that holds and fixes the holder and base in an arbitrary positional relationship, and a guide ring that is airtightly fixed, a groove is formed in the guide link, and the groove and the cylindrical part of the holder are loosely connected. An optical coupling device is obtained, which is characterized in that the guide ring and the holder are fitted together, and the guide ring and holder are fixed at the joint.

This invention can be applied regardless of the material of the light emitting element, and regardless of whether it is a semiconductor laser or a light emitting diode.
A detailed explanation will be given with reference to the drawings, focusing on the case of coupling a semiconductor laser and a single mode optical fiber.

FIG. 1 is a conceptual cross-sectional view showing a conventional coupling device, in which a semiconductor laser 1 is fused and fixed to a stem 3 via a heat sink 2 made of diamond or the like.

The coupling element 4 (illustrated in this example as a ball lens) is
It is identified in the holder 5 in an airtight state. The guide link 6, which is airtightly fixed to the stem 3, and the holder 5 are loosely fitted. The stem 3 and holder 5 are each held by a fine movement table (not shown), and the emission pattern of the semiconductor laser 1 is monitored with an infrared television camera or the like through the coupling element 4 to determine the coupling efficiency to a predetermined optical fiber (not shown). Adjust the positional relationship between the stem 3 and holder 5 so that the
By heating and melting the solder material 7 (not shown), it is possible to fix the solder material 7 in an optimal state. Optical semiconductor devices, such as semiconductor lasers 1, are usually exposed to the atmosphere because the reflective surface formed by cleavage and the fallen part of the pn junction are oxidized by oxygen in the air, deteriorating the operating characteristics and impairing reliability. It must be hermetically sealed in an inert gas atmosphere. However, in the conventional method, there is no way to uniformly melt and bond the solder material 7 over the entire circumference of the holder 5 and guide ring 6, so the positional relationship between the ball lens 4 and the semiconductor laser 1 is varied from several μm to several tens of μm.
Fine adjustment is made within the range of 14 degrees, and the 14 related parts are fixed with soldering, and at the same time the speed is 10-8a0-8at/sec or more (it is extremely difficult to make a sealing metal, and the yield rate is had the disadvantage of being extremely small.

FIG. 2 is a conceptual sectional view showing a further embodiment of the invention, in which the same members as in FIG. 1 are given the same numbers. A semiconductor laser 1 is fused and fixed to a stem 3 via a heat sink 2 made of diamond, silicon, or the like. The coupling element 4 (shown as a ball lens in this example) is fixed to the holder 15 in an airtight manner. At this time, in order to obtain a good airtight state, it is preferable that the material of the holder 15 be made of glass and fused using low melting point glass.

A guide link 16 is fixed concentrically to the stem 3 by welding and is airtight. The characteristic point here is that a grooved ring 11 as shown in the figure is formed on the upper part of the guide link 16, and the cylindrical part of the holder 15 fits loosely into the grooved ring 11. It has a shape that bulges outward at the center of the cylinder.

The actual adjustment and fixing work is carried out by holding the stem 3 and holder 15 on the fine movement table with the coupling element 4 facing upward (
(not shown) is essential. In this positional relationship, one of the purposes of the bulging portion of the cylindrical portion of the holder 15 is to set the separately formed ring-shaped solder taplet 17 in a predetermined position with good reproducibility. Next, similarly to the example in FIG.
The entire passage is monitored with an infrared television camera, etc., and the positional relationship between the stem 3 and the holder 15 is adjusted so that the coupling efficiency to a predetermined optical fiber (not shown) is maximized.
The solder material 17 is melted in a heating bath using a high frequency coil (not shown) installed around the solder material 17.

Another purpose of the bulge in the cylindrical portion of the holder 15 is to allow the molten solder material 17 to fall uniformly into the gap between the guide ring 16 and the holder 15. At this time, guide ring 1
By applying high-quality gold plating to the metal parts of the holder 6 and the holder 15, the probability that one heated and melted solder ring 17 will evenly wet the space between the holder and the guide link is 4.
It has been improved by ~5 times, and when 50 prototypes were produced, 130 were 1
An airtight state of 0-810-8 at/sec was obtained. Next, when the number of solder rings 17 was changed to two, the melted solder material accumulated in the groove 11, and the rate was 100-8 at*cc/s.
It was found that the rate of achieving an airtight state of ec or higher was significantly improved to 90% or more. At this time, the fine adjustment between the light emitting element 1 and the coupling element 4 can be made in exactly the same way as in the case of Fig. 1, so that the light for single mode optical fibers, which requires high airtightness and high precision position adjustment, Coupling devices can now be obtained with high yield and good reproducibility.

The present invention has been explained above mainly using a semiconductor laser and a ball lens as the light emitting element 1 and the coupling element 4. Needless to say, the present invention can also be used for optical loft lenses, etc. In the embodiments of the present invention, an optical element is used as an example of an optical element, but a known light-receiving element may also be used.

[Brief explanation of the drawing]

FIG. 1 is a conceptual sectional view showing a conventionally proposed coupling device, and FIG. 2 is a conceptual sectional view showing an embodiment of the present invention. Here, 1 is a semiconductor laser, 2 is a heat sink, 3 is a stem, 4 is a ball lens, 5, 15 holder, 6
, 16 is a guide ring, 7.17 is a solder material, and 11 is a grooved ring.

Claims (1)

[Claims] a base for holding an optical element; a holder for airtightly holding a coupling element optically coupled to the optical element; and an airtight seal for holding and fixing the holder and the front dC base in an arbitrary positional relationship. In the optical coupling device, a groove is formed in the guide ring, and the groove part and the cylindrical part of the boulder are loosely fitted together. An optical coupling arrangement characterized in that the guide ring and the holder are fixed.