JPS6076709A - Optical coupling device - Google Patents

Abstract

PURPOSE:To enable fixing of a light emitting element and a coupling element at <=1mum deviation from an optimum adjusting position by the constitution in which the coupling element is held by a holder consisting of a plastic material so as to be coupled optically to a photoelectric transducer and these elements are sealed in a hermetic case provided with window pane. CONSTITUTION:A spherical lens 4 is thermocompression bonded to a stem 3 via a holder 5' and a cap 8 is provided on the outside thereof to seal hermetically the lens against the external air. Window pane 9 on which an antirefleting film is formed is attached to the cap 8 in the exit direction of light to constitute an optical coupling device. The holder 5 is preliminarily fixed to the stem 3 by thermocompression bonding or the like at about 100mum mechanical accuracy and thereafter the position of the lens 4 is adjusted to an optimum state while the light emitting pattern of a semiconductor laser 1 is monitored by an IR television camera or the like through the coupling element 4. The holder 5' consists of a plastic metal and therefore the position of the lens 4 is easily adjustable even after the lens is fixed to the stem 3. The lens is subjected to work hardening after the adjustment, by which the mechanical strength is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical coupling device, and more particularly to a coupling device between a photoelectric conversion element and an optical 7-eye for optical information transmission.

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

In optical fiber communication systems, high-quality light beams emitted from semiconductor lasers and light-emitting diodes can be efficiently
Jin is developing a method to connect optical fibers, which is an important issue. To this end, 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 spherical lens or a cylindrical lens is placed between the light emitting element and the optical fiber. The coupling element of Nire et al. needs to 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 in accordance with the theoretical value, their positioning must be performed with extremely high precision.

For example, when coupling a semiconductor laser beam oscillating in a single mode to a single mode optical fiber, in order to suppress the decrease in coupling efficiency to 1 dB, it is necessary to
The coupling element must be adjusted and fixed within about μm, and within about ±2 μm in a plane perpendicular to the emission direction.

The work of adjusting and fixing the coupling element is usually done by energizing the fixed light emitting element to stop it from emitting C, and then monitoring this emitted beam with an infrared television or camera, or attaching and detaching it while measuring the optical fiber output. The coupling element attached to Nako1 adjustment jig and 9
+ )' + Z Adjust in the three axes directions to determine the optimal position. At this time, the light emitting element and the coupling element are attached to a metal member that can be fixed by soldering or welding.
It should be possible to fix it in the i11 position. However,
In actual experiments, when fixing by soldering or welding, due to the temperature difference during bonding, the number/Z
A positional shift of about ln occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coupling device for a light emitting element and an optical fiber, which has been made in order to solve the above-mentioned drawbacks, in which the light emitting element and the coupling element can be fixed with a deviation of 1 .mu.n or less from the optimum adjustment position.

The object of the present invention is to provide a coupling device that achieves high coupling efficiency and good reproducibility.

According to this invention, there is provided a base for holding a photoelectric conversion element, a holder for holding a coupling element optically coupled to the photoelectric conversion element, and an airtight container with a window glass for sealing the photoelectric conversion element and coupling element from outside air. An optical coupling device is obtained, characterized in that the holder material holding the coupling element is made of a plastic metal.

Although this invention can be applied regardless of the material of the light emitting element and regardless of the semiconductor laser or light emitting diode, the combination of a semiconductor laser that oscillates in a single mode and a single mode optical fiber is considered to have the greatest effect. The case will be explained in detail with reference to the drawings.

FIG. 1 is a conceptual cross-sectional view showing a conventionally proposed 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 (shown as a ball lens in this example) is hermetically fixed to the holder 5. The guide ring 6, which is fixed to the stem 3 by a bar, and the holder 5 are loosely fitted. The stem 3 and the 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, and a predetermined optical fiber (not shown) is connected to the stem 3 and the holder 5. By adjusting the positional relationship between the stem 3 and the holder 5 so as to maximize the coupling efficiency to the holder 5, and by heating and melting the solder material 7 in that state, the solder material 7 can be fixed in an optimal state. Optical semiconductor devices such as the laser 1 are usually exposed to nitrogen, etc. because the reflective surface formed by cleavage and the exposed part of the p"-" junction are oxidized by oxygen in the air, deteriorating operating characteristics and impairing reliability. However, in the conventional method, it is not easy to fix the ball lens 4 and the holder 5 hermetically and with sufficient strength. 1 positional relationship from several μm to several tens of μm
If it is extremely difficult to make fine adjustments within the range of m, fix their positional relationship with the solder material 7, and simultaneously perform barmetching and sealing at the same time, there is a drawback that the yield is extremely low.

FIG. 2 is a conceptual sectional view showing one embodiment of the present invention, and the same members as in FIG. 1 are given the same numbers. The ball lens 4 is thermocompression bonded to the stem 3 via a holder 5', and a cap 8 is formed on the outside of the lens 4, and a window glass 9 coated with an anti-reflection film is attached in the light emission direction. It is. The holder 5' is made of a plastic metal such as oxygen-free copper, and has a three-legged or five-legged structure. In this structure, 100 μm
The holder 5' is fixed to the stem 3 by thermocompression bonding or the like with a certain level of mechanical precision, and then the light emitting pattern of the semiconductor laser 1 is passed through the coupling element 4 using an infrared television camera or the like in the same manner as in the case of FIG. The position of the ball lens 4 is adjusted to the optimum state while monitoring. At this time, since the holder 5' is not made of plastic metal such as oxygen-free copper and has a three-legged structure,
Even after the foot is fixed to the stem 3, the position of the ball lens 4 can be easily adjusted, and after adjustment, the mechanical strength is increased by work hardening. v! The range in which I can be adjusted is 20 to 30 μm in the light output direction, and approximately 100 μm in the in-plane direction perpendicular to the light output direction, and the obtained coupling efficiency is 0.5 dB compared to the optimal state.
The following deterioration could be achieved.

Since the holder 5' has a structure that cannot be sealed, a sealing cap 8 is hermetically sealed to the stem 3 on the outside by thermocompression bonding or the like.

In the direction of light emission, there is a window glass 9 with anti-reflection coating.
However, it is a sealed type and is marked 9, so that the light beam emitted through the window glass 9 can be coupled to any optical fiber (not shown) such as an optical fiber.

The coupling device with this structure also showed good results in mechanical strength tests, and for example, no axis deviation of the light beam was observed in 100G acceleration tests, 1m drop tests, and 0 to 100°C temperature cycle tests. No deterioration of coupling efficiency occurred. Further, the deviation of the light beam was extremely small in the temperature range of 0 to 50°C, and no problems occurred in practical equipment.

In this way, after mechanically attaching the coupling elements,
By making fine adjustments using the plasticity of the material and creating a sealing structure with a separate cap,
The man-hours for high N degree R adjustment can be significantly reduced, and the manufacturing yield is
We were able to raise the value to almost the same as a single product without a coupling element.

The above light emitting element and coupling element are combined into a semiconductor laser, a ball lens and [
Although the present invention has been described in detail for the case of 7, the present invention can also be applied to other light emitting devices, such as edge emitting type and surface emitting type light emitting diodes, and also to other coupling elements such as a cylindrical lens instead of a ball lens. Needless to say, it is applicable.

Further, according to the device of the present invention, it is also possible to arrange a light receiving element instead of the light emitting element. Therefore, the present invention is useful as an optical coupling device between a light II conversion element and an optical fiber.

[Brief explanation of drawings]

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. 1...Semiconductor laser, 2...Heat sink, 3...Stem, 4...Coupling element, 5.5'...Holder, 6...Guide ring, 7...Solder material, 8...Gap, 9...Window glass. ,・′−゛− Figure 2

Claims (1)

[Claims] An optical coupling consisting of a base that holds a photoelectric conversion element, a holder that holds a coupling element that optically couples to the photoelectric conversion element, and an airtight container with a window glass that protects the photoelectric conversion element and coupling element from outside air. An optical coupling device characterized in that the holder material holding the coupling element is made of a plastic metal.