JPH0576603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for emitting and deriving an electrical signal using a light emitting element in an optical communication system, or for receiving a transmitted optical signal.

[Conventional technology]

A conventional light-emitting and receiving device for optical communication (hereinafter, a light-emitting device will be explained as an example) has a stem base 1 and a light-emitting element 2 equipped with a lead 1a, as shown in FIG. A casing 4 is joined to the system base 1 so as to be housed in the internal space 3 airtightly with the outside air, and an optical fiber 7 is inserted into a thin light 6 formed in a capillary 5 in the center of the casing 4. The tip of the optical fiber 7 is fixed at a position protruding from the capillary 5, facing the light emitting element 2. In this case, after the optical fiber 7 is inserted into the pore 6 of the capillary 5, in order to fix it, the end of the capillary 5 is bonded into the recessed part 5a, which is cut into a conical shape, using a synthetic resin adhesive as a fixing means. , glass, solder, or other bonding agent 8 is injected and filled into the optical fiber 7 .
is fixed in a predetermined position, and maintains the airtight sealing property of the pore 6.

Note that the conventional capillary 5 was made of metal.

[Problem that the invention seeks to solve]

However, when a resin adhesive is used as a means for bonding and fixing the optical fiber 7, it can be easily filled and fixed, but the adhesive may peel off over a long period of time, or the optical fiber 7 may not be fixed. The casing 4 has a capillary 5 brazed in advance.
This had a major drawback in that the reliability was low, such as the bonding force being reduced even at high temperatures when brazing the 2-piece to the stem base 1. Further, even if the solder is injected and fixed, there is a risk that the casing 4 will melt due to the high temperature when brazing the casing 4 to the stem base 1. Furthermore, in cases where the optical fiber 7 is welded with low melting point glass, cracks may occur in the optical fiber 7 due to stress caused by the difference in thermal expansion coefficients between the optical fiber 7, which is surrounded and fixed by the low melting point glass, and the glass. It had drawbacks such as stopping the guiding function. Furthermore, in any of the above cases, it is difficult to maintain complete airtightness of 1×10 ^-8 cc/sec or more between the optical fiber 7 and the capillary 5.
Even if the airtightness is maintained for one hour, the airtightness is likely to be impaired over a long period of time, and air will flow in, resulting in a decline in the light emitting function of the light emitting element 2 installed in the internal space 3 in an exposed state. There was a drawback.

[Means for solving problems]

In order to solve the above-mentioned problems, it is necessary to maintain the joint of the optical fiber 7 inserted into the pore 6 of the capillary 5 in a good airtight state for a long period of time. The coefficient of thermal expansion is brought closer to that of optical fiber,
For optical communications, the capillary 5 and the optical fiber 7 are fixed with glass having a thermal expansion coefficient equal to or lower than that of the optical fiber 7 to be inserted, and a completely airtight seal is achieved. The present invention aims to provide a light emitting light receiving device.

〔Example〕

FIG. 1 is a cutaway view of the main parts of a light emitting device H as an optical communication light emitting and receiving device according to an embodiment of the present invention, and the same parts as in the conventional example (FIG. 3) are given the same reference numerals. I will explain.

Reference numeral 1 denotes a stem base, and a light-emitting element 2 that is activated to emit light by supplying electricity through a lead 1a is attached to the stem base 1 in an exposed state, and this light-emitting element 2 is housed in an internal space 3 without being exposed to the outside air. In order to do this, the casing 4 is brazed to the stem base 1 and sealed. Further, a capillary 5 made of ceramic is airtightly attached to the center of the casing 4, and an optical fiber 7 is inserted into a pore 6 made in the capillary 5. They face each other so as to be able to receive light from the element 2, and are fixed in a protruding state from the capillary 5.

In this case, in order to fix the optical fiber 7 inserted into the pore 6 of the capillary 5, the end of the capillary 5 is fixed by filling the concave notch 5a cut out in a conical shape with glass G. Ru. Also,
In order to increase the bonding strength of the optical fiber 7 to the capillary 5 and to improve the airtightness, the capillary 5 is
A deep recessed part 5b is formed in the recessed part 5.
It may be filled with glass G so as to surround and weld the fiber 7 inserted through the inside of the capillary 5. In this case, the inner wall surface of the concave notch 5b of the capillary 5 and the outer surface of the optical fiber Since the bonding area of the glass G is increased, airtightness can be further improved.

By the way, as mentioned above, the glass G to be filled in the recessed parts 5a and 5b of the capillary 5 has heat resistance and good weldability to the fiber 7 and the capillary 5 made of ceramic material, thereby achieving high airtightness. It is desirable to have something that can be maintained for a long period of time.

In addition to the above characteristics, an important factor is the relationship with the coefficient of thermal expansion of the optical fiber 7 and the capillary 5.

Therefore, when we measured the thermal expansion coefficients of each of the capillary 5 made of ceramic material (mainly alumina ceramic) and the optical fiber 7 made of silica glass, we found that the capillary 5 made of ceramic was 7 to 8
Fiber 7 had a coefficient of thermal expansion of 0.5× ^{10 -6} /°C. Capillary 5 like this
We repeated various experiments to examine the suitability of the thermal expansion coefficient of the glass G used to join the optical fiber 7 and the capillary 5, and found that this glass G has a thermal expansion coefficient between the capillary 5 and the optical fiber 7. It has been found that a stable bonding state can be maintained without causing breakage of the optical fiber 7 or deterioration of airtightness, especially during thermal changes.

Therefore, examples of glass materials having a coefficient of thermal expansion within this range include borosilicate glass (2×10 ^-6 /°C);
Lead glass (4 to 5 x 10 ^-6 /°C) was the most practical.

In this way, the concave notches 5a and 5b of the capillary 5
Among them, the glass G for bonding and sealing the optical fiber 7 is at least one having a thermal expansion coefficient equal to or lower than that of the capillary 5, and more preferably one having a thermal expansion coefficient of the optical fiber 7. The above-described materials exhibited excellent characteristics under various conditions after bonding.

In the above embodiment, a light emitting device including a light emitting element 2 has been described, but the present invention is not limited to this, and the same applies to a light receiving device including a light receiving element.

〔Effect of the invention〕

When an optical fiber is bonded and sealed to a capillary made of ceramic in order to configure a device that emits or receives an optical signal as described above, a ceramic capillary having a coefficient of thermal expansion equal to or lower than that of the capillary is used. Since the fiber is fixed with a glass material, the optical fiber will not break ^or lose its airtightness, and the
It is possible to maintain airtightness over sec, therefore,
It has many advantages, such as not reducing the performance of the light-emitting element and light-receiving element, and also not being affected by the heat during brazing the stem base and casing during manufacturing, and maintaining high reliability over a long period of time. It has unique characteristics and its contribution to high-quality optical communications is enormous.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of the light emitting and receiving device for optical communication according to the embodiment of the present invention, and FIG. FIG. 3 is a partially broken sectional view showing an example of a conventional light emitting/receiving device for optical communication. 1... Stem base, 2... Light emitting element, 4...
Casing, 5... Capillary, 7... Optical fiber, G... Glass.

Claims (1)

[Scope of Claims] 1. One end of an optical fiber is inserted into a pore of a capillary made of ceramic so as to protrude from the pore of the capillary so as to lead out light from a light emitting element or introduce it into a light receiving element, The optical fiber is fixed to the capillary by melting and filling glass having a coefficient of thermal expansion equal to or lower than that of the capillary into a concave notch formed continuously at the end of the capillary. A light emitting and receiving device for optical communication. 2. The light emitting/receiving device for optical communication according to claim 1, wherein the glass has a thermal expansion coefficient between that of the capillary and the optical fiber.