JPH06148449A - Optical fiber coupling device - Google Patents

Abstract

PURPOSE:To make efficient welding possible which does not affect coupling characteristics and to easily know the direction and position of the tip of an optical fiber from outside by mutually welding a holder and a ferrule in a through hole. CONSTITUTION:The tubular holder 10 has radius-directional through holes 15 and 17 for welding and those holes 16 and 17 are formed at positions which are shifted by about 180 deg. in the circumferential direction and are shifted >=a minimum distance even in the axial direction. This distance is so set that the coupling device becomes mechanically stable and the influence upon the optical coupling characteristics is reduced below a desired level. Zones 18 and 20 of welding to the tubular ferrule 12 are each three places of the internal edges of the through holes, and consequently mechanical strength is obtained to prevent vibration. The ferrule 12 has a axially extending flat surface of constant width on its outer peripheral surface and this flat surface extends from the tip 22 to a position beyond the upper end of the holder 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber coupling device, and more particularly to an optical fiber coupling device in which the direction of an optical fiber can be easily discriminated.

[0002]

2. Description of the Related Art In optical communication, a means for coupling a light emitting element such as a semiconductor laser and a light receiving element to an optical fiber is indispensable, and a module in which a semiconductor laser and an optical fiber are coupled and integrated is used. . Extremely high precision is required for assembling such a coupling means, the optical fiber is firmly supported in the inner hole of the ferrule, and the ferrule is installed in the laser device after precise setting of the predetermined inner end position and angle of the optical fiber. It is welded to an optical holder which is fixed to the metal housing by welding.

FIG. 4 shows a typical example of a conventional optical fiber coupling device as described in, for example, Japanese Patent Application Laid-Open No. 1-145608, in which an optical element 1 (or a light receiving element) for generating a laser beam is made of stainless steel. A metal tubular ferrule 3 made of stainless steel or the like, which is housed in a metal housing 2 made of stainless steel or the like and holds an optical fiber 4 in a shaft hole, is welded to a metal holder 6 made of stainless steel or the like via a welding point or line 5 by laser welding. Then, the holder 6 is welded and fixed to the housing 2 via the welding point or line 7 by laser welding. In order to perform proper optical coupling, the tip of the optical fiber is fixed to a predetermined position with respect to the optical element 1 and the lens system 8 prior to welding, and is oriented in a predetermined direction and mechanically stable against external force. The positioning and fixing of each such member must be done correctly. In the welding method as shown in Fig. 3, since the welding of the ferrule and the holder is formed at several points or along the circumference in the same plane perpendicular to the axis, vibration may occur at the welding point as an axis. If there is a defect even in the place, a deviation occurs in the direction perpendicular to the optical fiber axis, and the optical coupling characteristics are greatly affected. This problem is, like Jitsukaihei 3-92610,
This is avoided by providing the welding points of the ferrule and the holder at equal intervals in two planes perpendicular to the axis.

[0004]

However, this method requires a large number of welding points, which impairs workability. Therefore, an object of the present invention is to provide an optical fiber coupling device having a structure capable of efficient welding without affecting the coupling characteristics. Further, in the conventional optical fiber coupling device, it is not possible to directly observe the fiber tip by performing welding and fixing between the members while properly setting the direction of the tip (ferrule end surface) of the obliquely polished fiber in a predetermined direction. Therefore, the adjustment work took a lot of trouble. Therefore, another object of the present invention is to provide an optical fiber coupling device having a structure in which the direction of the tip of an optical fiber can be easily known from the outside. Further, in the conventional optical fiber coupling device, since the fiber tip cannot be directly observed, it takes a lot of time and labor to adjust the tip position when welding the members. Therefore, another object of the present invention is to provide an optical fiber coupling device having a structure in which the tip position of an optical fiber can be easily known from the outside.

[0005]

An optical fiber coupling device according to the present invention comprises a tubular holder, a tubular ferrule supported by an inner hole of the tubular holder, and an optical fiber supported by an axial hole of the ferrule. In the optical fiber coupling device, the holder has a radial through hole at a position displaced by approximately 180 degrees in the circumferential direction and axially, and the holder and the ferrule are welded to each other in the through hole. It is characterized by According to another aspect, an optical fiber coupling device of the present invention comprises a tubular holder, a tubular ferrule supported by an inner hole of the tubular holder, and an optical fiber supported by an axial hole of the ferrule. In the above, the ferrule has a flat surface on its outer peripheral surface that extends to the outside of the holder with a constant width. This flat surface of constant width preferably extends a fixed length from the tip of the optical fiber.

According to the present invention, an optical coupling portion having a predetermined mechanical stability can be obtained without the complicated and troublesome work required in the prior art. The flat surface of the ferrule makes it possible to easily know the orientation of the tip of the fiber and the welding operation can be carried out accurately and quickly.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical fiber coupling device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an elevational view of the optical fiber coupling device of the present invention, which is partially cut away, FIG. 2 is a plan view of the same, and FIG. 3 is a central longitudinal cross-sectional view of FIG. 1 seen from the left. An optical element or a light receiving element for generating a laser beam and a lens system are housed in a metal housing such as stainless steel (not shown) and are positioned below the optical fiber coupling device shown in FIG. 1. I will not explain it because it has nothing to do with.

1 to 3, reference numeral 10 is a stainless steel tubular holder having a flange 11 for welding and fixing to a housing. Reference numeral 12 is a stainless steel tubular ferrule welded to the inner hole of the holder 10. The ferrule 12 fixedly houses the optical fiber 14 in its axial hole. The optical fiber 14 generally has a ceramic guide (capillary).

The holder 10 is formed with radial through holes 16 and 17 for welding. These holes 16, 1
7 is formed at a position displaced by approximately 180 degrees in the circumferential direction and displaced by a minimum distance in the axial direction. Such a distance is such that the coupling device is mechanically stable and reduces its effect on the optical coupling properties below a desired level. As shown in FIG. 2, welding points 18 and 20 with the ferrule 12 are at least three points on each of the inner edges of the through holes. As a result, an effect equivalent to that of the above-mentioned welding method of Japanese Utility Model Laid-Open No. 3-92610 can be obtained, mechanically strengthened and vibration can be prevented. The screw holes 26 (or 27) are formed at arbitrary positions deviated from these through holes by about 90 degrees. This screw hole is for inserting a set screw for fixing the positional relationship of the ferrule 12 with respect to the holder 10 prior to welding.

The ferrule 12 has a flat surface 24 having a constant width and extending in the axial direction on the outer peripheral surface thereof. The flat surface 24 extends from the tip 22 to a position beyond the upper end of the holder 10 as shown in FIG. If the relative position and relative orientation of the optical fiber 14 and the flat surface 24 are predetermined, the direction of the fiber tip can be easily known by observing the flat surface 24 from the outside with, for example, an optical measuring device, and the welding work can be performed accurately. Can be implemented quickly. Further, if the flat surface having a constant width is placed with a constant length, the position of the tip of the optical fiber can be easily known by measuring the position of the upper end 28 thereof, so that the welding operation can be performed accurately and promptly. If the tip 22 of the ferrule 12 is cut with an oblique plane, the return light can be reflected and blocked.

The fixing between the members is performed by aligning and positioning the tip of the optical fiber 14 and the optical system using a predetermined flat surface 24, welding to the optical system housing of the holder, and laser light to the ferrule of the holder. Weld. The holder and the ferrule are set by inserting a set screw into the screw hole 26. At this time, if the flat surface 24 is sufficiently long, it may be used to fix the set screw to this surface.

[0012]

According to the present invention, the following effects and benefits are obtained. (1) Since the holder has a radial through hole at a position shifted by 180 degrees in the circumferential direction and shifted in the axial direction, and the holder and the ferrule are welded to each other in the through hole. An optical coupling unit having a predetermined mechanical stability can be obtained without complicated and troublesome work. (2) Since the ferrule has a flat surface on its outer peripheral surface that extends to the outside of the holder with a constant width, the direction of the fiber tip can be easily known, and welding work can be performed accurately and quickly. In addition, if the length of a flat surface with a certain width is set constant,
Since you can easily know the position of the optical fiber tip,
Welding work can be performed accurately and quickly.

[Brief description of drawings]

FIG. 1 is an elevational view of an optical fiber coupling device of the present invention, shown partially broken away.

2 is a plan view of the optical fiber coupling device of FIG. 1. FIG.

3 is a central longitudinal cross-sectional view of the optical fiber coupling device of FIG. 1 as viewed from the left.

FIG. 4 is a schematic view of a conventional optical fiber coupling device.

[Explanation of symbols]

 10: Tubular holder 12: Tubular ferrule 14: Optical fiber 15: Clad 16, 17: Through hole 18, 20: Welding point 22: Tip 24: Flat surface 26 (27): Screw hole 28: Upper end

Claims (5)

[Claims] 1. An optical fiber coupling device comprising a tubular holder, a tubular ferrule supported in an inner hole of the tubular holder, and an optical fiber supported in an axial hole of the ferrule, wherein the holder is substantially circumferentially aligned. An optical fiber coupling device, characterized in that a radial through hole is provided at a position shifted by 180 degrees and axially, and the holder and the ferrule are welded to each other in the through hole. 2. An optical fiber coupling device comprising a tubular holder, a tubular ferrule supported by an inner hole of the tubular holder, and an optical fiber supported by an axial hole of the ferrule, wherein the ferrule has an optical fiber on an outer peripheral surface thereof. An optical fiber coupling device having a flat surface extending to the outside of the holder along the axis of the fiber. 3. The optical fiber coupling device according to claim 2, wherein the flat surface extends from the tip of the optical fiber to a constant length. 4. The optical fiber coupling device according to claim 1, wherein the ferrule has an outer peripheral surface having a flat surface extending to the outside of the holder. 5. The optical fiber coupling device according to claim 4, wherein the flat surface having a constant width extends from the tip of the optical fiber to a constant length.