JPH07199003A - Housing structure for optical element - Google Patents

Abstract

PURPOSE:To fix an optical fiber at an oblique incidence angle without applying any unreasonable force to the optical fiber by setting the axis of a pipe for fiber penetration at an angle of deviation to the prolongation of a terminal to which the optical fiber of the optical element is connected. CONSTITUTION:The axis 2 of the pipe for fiber penetration for leading the optical fiber out of a housing 1 is provided at the angle theta of deviation to the prolongation 3 of the terminal to which the optical fiber of the optical element is connected. Consequently, even when the light from the optical fiber is made incident slantingly on the end surface of an optical waveguide (parallel to the length axis of the element) formed on the element, the degree of curvature of the optical fiber is small, so the optical fiber can be sealed and fixed at the oblique incidence angle which is ideal for the coupling between the element and optical fiber without applying any unreasonable force to the optical fiber. When this angle of deflection is 2-5 deg.', an excellent result is obtained for the angle of oblique incidence on the optical element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing structure for hermetically sealing an optical element such as a waveguide type optical modulator.

[0002]

2. Description of the Related Art Solder sealing and seam welding are already known as a housing structure and means for hermetically sealing an optical element. As described above, as a means for introducing the optical fiber into the housing in a hermetically sealed state, a vapor phase film deposition technique such as a vapor deposition method or a sputtering method is formed on the surface of the bare optical fiber.
Alternatively, a method (metallizing process) of forming a metal layer made of one or both of nickel and gold by electroless plating and soldering the metal layer and a corresponding portion of the housing (made of metal) to each other is taken.

The tubular sleeve portion, which is a penetrating pipe for guiding the optical fiber into the housing, has an inner diameter of about 1 mm corresponding to the outer diameter (0.9 mm) of the coating of the optical fiber, and needs to be filled with solder. , Bare optical fiber (diameter 0.125
mm) and the inner diameter of the pipe, the inner diameter of the pipe may be reduced to, for example, about 0.6 mm.

Conventionally, such a pipe (sleeve) for penetrating an optical fiber is generally parallel to the axis of the housing, as in the case of a laser device which has already been proven as a hermetically sealed optical device. .

[0005]

By the way, in the waveguide type electro-optical element, which is attracting attention as an external modulator of an optical communication system, the coupling efficiency between the waveguide and the optical fiber is increased,
Specifically, it is generally performed to fill the interface with an adhesive having a low refractive index and to adopt an oblique incidence method in order to reduce the light reflection at the coupling portion.

By the way, in the case of a structure parallel to the axis of the housing (which can be said to be the normal to the mounting surface of the housing) like a conventional optical fiber penetrating pipe (sleeve), the fiber is placed in a narrow space of 1 mm or less in inner diameter. When the optical fiber is bent to give an angle of oblique incidence (for example, an angle of 5 to 7 ° is common) to the optical element in a passed state, the bare optical fiber collides with the end edge of the penetrating pipe and Fiber breaks,
Problems such as scratches occur.

On the other hand, in the case of a very small element, the above problem can be solved by mounting the element relatively obliquely inside the housing so that a desired incident angle can be obtained. However, if the element length is as long as several centimeters and the parts / structure of the electrode introduction part is specified to a specific shape for inputting a high frequency external signal, such as a waveguide type high speed modulator, The operation to mount diagonally
Not always easy.

Therefore, there is a demand for a housing structure that has both a high-performance structure such as oblique fiber incidence for reducing reflection at the coupling portion and a high-reliability structure such as hermetic sealing. Therefore, the present invention provides an optical element casing structure capable of sealing and fixing an optical fiber at an oblique incident angle ideal for coupling the element and the optical fiber without applying an excessive force to the optical fiber. The purpose is to do.

[0009]

In the present invention, the first means for solving the above problems is, as shown in FIG. 1, a casing structure for enclosing an optical element to which an optical fiber is connected, The axis 2 of the fiber-penetrating pipe for pulling out the optical fiber to the outside of the housing 1 is provided with a deviation angle θ with respect to the extension line 3 of the terminal to which the optical fiber of the optical element is connected.

The second means of the present invention is to set the deflection angle θ between the axis 2 of the fiber penetrating pipe of the first means and the extension line 3 to 2 ° to 5 °. And in the present invention, the third means is that the inner end of the housing of the fiber penetrating pipe of the first or second means and the optical fiber passing through this penetrating pipe are joined by solder, and The outer end of the housing of the penetrating pipe and the optical fiber are bonded with an adhesive.

[0011]

According to the present invention, the shaft of the penetrating pipe is provided with an angle of deviation with respect to the extension line of the terminal to which the optical fiber of the optical element is connected. Therefore, the optical fiber is formed in the element. Even if the light is obliquely incident on the end face of the optical waveguide (parallel to the longitudinal axis of the element), the bending of the optical fiber is at least as small as possible, so the element and the optical fiber can be coupled without applying excessive force to the optical fiber. The optical fiber can be sealed and fixed at an ideal oblique incident angle.

If the angle of deviation is 2 ° to 5 °,
Good results can be obtained for the angle of oblique incidence on the optical element. The reason for this is that, as shown in FIG. 1, the element end face 4a is tilted by 5 ° from the plane perpendicular to the waveguide axis 5 and cut and ground, while the glass for reinforcing the adhesion between the optical fiber and the element end. The end face of the capillary 6 (the side in contact with the element) is cut at an angle of 7 ° from the plane perpendicular to the fiber hole axis. Therefore, this formation angle allows the fiber to be incident at an angle of 7 ° with respect to the element end face and 7−5 = 2 ° with respect to the waveguide. These angles are set in accordance with the desired reflection loss amount, but such values are often taken because the insertion loss from the fiber to the waveguide increases if the angle becomes too large. Therefore,
As a housing structure for guiding the fiber in such a state, it is preferable that an angle between the axis of the fiber-penetrating pipe and the housing side direction is 2 to 5 °.

The inner end of the housing of the fiber-penetrating pipe and the optical fiber passing through the penetrating pipe are joined by solder, and the outer side of the casing of the penetrating pipe and the optical fiber are joined by an adhesive. Is being done
It is suitable from the viewpoints of hermetic sealing and fiber fixing strength.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical element housing structure according to the present invention will be described below with reference to the drawings. 2 to 7 show an embodiment of an optical element housing structure according to the present invention. In this example, as shown in FIGS. 7 (1), 7 (2) and 2 (1), the housing 10 has two optical fibers 1 for input and one for output.
An optical element 15 such as a waveguide type high speed modulator, which is connected to the optical fiber, is arranged inside of which both 1 and 12 are connected and which has two high frequency electrode connectors 13 and 14.

Referring to the enlarged views shown in FIGS. 2 (2) and 2 (3), a fiber-penetrating pipe is brazed and joined to the wall surfaces 16 and 17 of the housing through which the fiber penetrates. Guide holes 18 and 19 for the shaft 3
3, 34 are provided at an angle of 2 ° with respect to the extension line of the terminal to which the optical fiber of the optical element is connected, that is, the normal lines 31, 32 of the wall surface. The guide holes 18 and 19 are formed by coaxially forming the large diameter portions 18a and 19a on the outside of the wall surface and the small diameter portions 18b and 19b on the inside in two steps.

The guide holes 18 and 19 are shown in FIG.
As shown in, the fiber-penetrating pipe 20 is inserted. FIG. 3 shows the fiber penetrating pipe 20 joined to the guide hole of FIG. The pipe 20 is a tubular member having a through hole 24, a distal end 21 formed obliquely, and a flange portion 22 formed therein. The flange portion 22 is inserted into the large diameter portions 18a and 19a of the guide hole to form a casing. It has been brazed to the housing in advance at the manufacturing stage.

Then, the optical fiber is fixed using a core 25 and a rubber hood 27 as shown in FIGS. The core 25 is a member for positioning the fiber shaft substantially at the center of the pipe and fixing the coated portion of the fiber and the pipe with an adhesive, and is a tubular member having a crack 26. The rubber hood 28 is shown in FIG.
The large-diameter portion 2 that covers the fiber-penetrating pipe 20 as shown in FIG.
8 and a small diameter portion 29 that covers the optical fiber, and is fixed in the state shown in FIG.

According to this example, the fiber penetrating pipe 20
Is fixed in advance along the introduction path of the optical fiber, so that the bare portion 1a of the optical fiber 1 can be held substantially at the center of the fiber-penetrating pipe 20, and scratches and the like due to contact with the pipe can be imparted. There is no. Then, the bare portion 1a of the optical fiber whose surface is metallized and the fiber penetrating pipe 20 are soldered at the tip portion 21 of the pipe as shown in FIG. 6, and the airtightness is maintained at this portion. .

On the other hand, the joint between the core 25 and the optical fiber 1 is sealed with an adhesive inside the rubber hood 27. Therefore, according to the optical element housing structure according to the present embodiment, it is possible to seal and fix the optical fiber at an ideal oblique incident angle for coupling the element and the optical fiber without applying an unreasonable force to the optical fiber. It is possible to provide a housing structure of an optical element capable of

FIG. 8 shows another embodiment of the optical element housing structure according to the present invention. In this embodiment, the wall surface 40 of the housing through which the optical fiber penetrates,
A guide hole 41 for brazing and joining the fiber-penetrating pipe is provided with its axis inclined by 2 ° with respect to the extension line of the terminal to which the optical fiber of the optical element is connected, that is, the normal line of the wall surface. Unlike the first embodiment, the guide hole 41 is not provided with a different diameter portion. Then, the optical fiber is penetrated by using a fiber penetration pipe 42 having a shape different from that of the first embodiment, a core 43 similar to that of the first embodiment, and a rubber hood 44.

In this embodiment, the bare portion 1a of the metallized optical fiber 1 is soldered 45 at the tip of the fiber-penetrating pipe 42, and the fiber-penetrating pipe 42 and the core 43 are connected. An adhesive is filled in the gap 46 between the two. Therefore, even in the optical element housing structure according to this embodiment, the optical fiber can be sealed and fixed at an oblique incident angle ideal for coupling the element and the optical fiber without applying an excessive force to the optical fiber. It may be a casing structure of an optical element.

[0022]

As described above, according to the present invention,
Since the axis of the fiber-penetrating pipe for pulling out the optical fiber from the housing is provided with a declination with respect to the extension line of the terminal to which the optical fiber of the optical element is connected, an unreasonable force is applied to the optical fiber. The optical fiber can be sealed and fixed at an oblique incident angle that is ideal for coupling the element and the optical fiber.

[Brief description of drawings]

FIG. 1 is a diagram showing a housing structure for an optical element according to the present invention.

2A and 2B are views showing an embodiment of a housing structure for an optical element according to the present invention, in which (1) is a schematic sectional view and (2) is II in (1).
An enlarged cross-sectional view of the portion, (3) is an enlarged cross-sectional view of the III portion in (1).

3 is a cross-sectional view showing a fiber penetrating pipe used in the optical element housing structure shown in FIG.

4A and 4B are views showing a fiber centering core used in the optical element housing structure shown in FIG. 2, where FIG. 4A is a sectional view and FIG.

5 is a cross-sectional view showing a protective rubber hood used in the optical element housing structure shown in FIG.

6 is a sectional view showing a state in which an optical fiber is attached to the optical element housing structure shown in FIG.

7A and 7B are views showing an overview of an optical element housing to which the present invention is applied, where FIG. 7A is a top view and FIG. 2B is a plan view.

FIG. 8 is a cross-sectional view showing a structure of an optical element housing according to another embodiment of the present invention.

[Explanation of symbols]

 1 case 2 axis of penetrating pipe 3 extension line 4 optical element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Sakuma 585 Tomimachi, Funabashi, Chiba Sumitomo Cement Corporation Optoelectronics Division (72) Inventor Hirotoshi Nagata 585 Tomimachi, Funabashi, Chiba Sumitomo Cement Co., Ltd. Central Research Center

Claims (3)

[Claims] 1. A housing structure for enclosing an optical element (4) to which an optical fiber is connected, wherein an axis (2) of a fiber-penetrating pipe for pulling the optical fiber out of the housing (1) is an optical element. The optical element casing structure is characterized in that a deviation angle (θ) is provided with respect to the extension line (3) of the terminal to which the optical fiber is connected. 2. A shaft (2) of the fiber-penetrating pipe.
And the deviation angle (θ) formed by the extension line (3) is 2 ° to 5 °
The optical element casing structure according to claim 1, wherein: 3. The inner end of the housing of the fiber penetrating pipe and an optical fiber passing through the penetrating pipe are joined by solder, and the outer end of the housing of the penetrating pipe and the optical fiber are bonded to each other. The optical element housing structure according to claim 1 or 2, wherein the optical element housing is bonded by an agent.