JPH0543081B2 - - 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 stem 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 pore 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 cut out into a conical shape using a synthetic resin adhesive as a fixing means. Bonding agents such as adhesives, glass, and solder 8
By flowing in and filling the optical fiber 7, the optical fiber 7 is fixed at a predetermined position and the airtight sealing property of the pore 6 is maintained.

[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 the 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 it 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 the case of welding with low melting point glass, cracks occur in the optical fiber 7 due to the stress caused by the difference in thermal expansion coefficient 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 airtightness is maintained temporarily, the airtightness is likely to be lost over a long period of time, causing air to flow in and reducing the light emitting function of the light emitting element 2 installed in the internal space 3 in an exposed state. There was a drawback of doing so.

[Means for solving problems]

In order to solve the above-mentioned problems, it is necessary to maintain the optical fiber 7 inserted into the pore 6 of the capillary 5 in a good airtight state for a long period of time. A metal film having a hardness at least equal to or less than that of the glass material used for bonding is applied to the surface of the capillary 5, and glass is attached to the capillary 5 so as to surround the metal film. The present invention aims to provide a highly reliable light emitting/receiving device for optical communication that is hermetically sealed.

〔Example〕

Fig. 1 is a cutaway view of the main parts of a light emitting device H as a light emitting and receiving device for optical communication 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. and 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 should protrude from the conical cutout 5a, and the exposed outer peripheral surface of the optical fiber 7 should be fixed. (Excluding the tip) aluminum, nickel, gold,
A metal film M such as silver or copper is deposited, and a glass G having a low melting point is placed in the recessed part 5 so as to surround this metal film M.
The optical fiber 7 is melted and filled into the capillary 5 and is sealed to the capillary 5. In this case, dry plating methods such as sputtering, vapor deposition, and ion plating are suitable for depositing the metal film M on the optical fiber 7, and the thickness of the metal film M is 125 μm in diameter. There is a limit to the thickness of the optical fiber 7 because it is coated on the surface of the optical fiber 7, so a thickness of about 0.1 to 10 μm is appropriate. In addition, as a result of various experiments using a metal for the metal film M, it was found that a metal with a hardness equal to or less than the hardness of the glass G to be welded and bonded (Mohs hardness 6) is desirable, and aluminum is particularly suitable. .

On the other hand, in order to increase the bonding strength of the optical fiber 7 to the capillary 5 and to improve the airtightness, a deeper recess 5b is formed in the capillary 5, as shown in FIG. 2, which shows a fractured surface of the capillary 5. It may be inserted into the recessed notch 5b and filled with glass G so as to surround the optical fiber 7 whose surface is coated with a metal film M and to be welded and bonded.
In this case, the bonding area of the glass G to the inner wall surface of the recessed part 5b of the capillary 5 and the outer surface of the optical fiber 7 is increased, and as a result, the airtightness can be further improved.

The glass G used for bonding should preferably have a melting point as low as possible, but it may be at least as long as it can withstand the temperature at which the casing 4 is brazed to the stem base 1 without melting. Since the metal film M absorbs and tolerates the difference in thermal expansion between the glass G, the capillary 5 made of ceramic, and the optical fiber 7 made of quartz glass, a commonly used low melting point glass can be used.

In the above embodiment, only a light emitting device including the light emitting element 2 has been described, but it is needless to say that the same technique can be applied to a light receiving device including a light receiving element.

〔Effect of the invention〕

As mentioned above, when bonding and sealing an optical fiber to a ceramic capillary to construct a device that emits or receives an optical signal, a metal film is deposited on the surface of the optical fiber at the part to be bonded, and the metal Since the membrane is surrounded by glass and bonded to the capillary, the optical fiber will not break or the airtightness will be compromised due to differences in the expansion of each member, ensuring a high level of airtightness for a long time. As a result, high reliability is maintained over a long period of time without degrading the performance of the light-emitting element or light-receiving element, and without being affected by the thermal effects of brazing the stem base and casing during manufacturing. It has many features, such as the ability to

[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, M: metal film.

Claims (1)

[Scope of Claims] 1. An optical fiber is inserted into a pore of a ceramic capillary so that one end of the optical fiber protrudes from the pore, and a metal film is coated on the outer peripheral surface of the optical fiber that protrudes from the capillary. A light emitting and receiving device for optical communication, characterized in that a glass is welded and sealed so as to surround a metal film. 2. The light emitting/receiving device for optical communication according to claim 1, wherein the metal film is made of a metal such as aluminum, nickel, tin, gold, silver, copper, etc. whose hardness is equal to or lower than that of glass. .