JPH05273436A - Working method and working device for end face of optical fiber - Google Patents

Abstract

(57) [Abstract] [Object] The present invention provides a method and apparatus for processing an end face of an optical fiber used in an optical connecting element, and more particularly, an inner side of an end face of an optical fiber clad where an optical fiber core face serves as a connecting face with an optical waveguide. And a method for etching an optical fiber end face suitable for optical coupling. The present invention relates to a method and apparatus for processing an optical fiber end face used in an optical connecting element, wherein the optical fiber end face is brought into contact with the liquid surface of the etching solution, and then the optical fiber end face is brought into contact with the liquid surface of the etching solution. Move it to a slightly higher position to etch only the end face of the optical fiber, and detect the contact state between the end face of the optical fiber and the liquid surface of the etching solution by measuring the reflected return light from the contact face and controlling the end face of the optical fiber. An etching processing method and processing apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for processing an end face of an optical fiber used for an optical connecting element, and more particularly, an optical fiber core face is located inside an end face of an optical fiber clad serving as a connecting face with an optical waveguide. The present invention relates to an etching method and an etching apparatus for an optical fiber end face suitable for optical coupling.

[0002]

2. Description of the Related Art Conventionally, as a method of processing an end face of an optical fiber by etching, there are ion beam etching, etching with hydrofluoric acid, and the like (for example, Japanese Patent Laid-Open No. 3-163406). However, the so-called ion beam method, in which a solid material is subjected to ion bombardment to scatter surface atoms in a vacuum, requires a large amount of equipment and requires a high processing cost. Further, since the etching speed is slow, it takes time to process. Further, in the case of etching with hydrofluoric acid, since the end of the optical fiber is simply immersed in the hydrofluoric acid solution for etching, the equipment and processing method are simpler than the ion beam method, and the optical fiber is etched. Although the speed is high and the time required for processing is short, the etched optical fiber is etched at the same time with the outer periphery of the portion immersed in hydrofluoric acid as shown in FIG. The outer diameter 1b of the portion becomes small. For example, FIG. 4 shows an example in which a single mode optical fiber is etched with a 46% hydrofluoric acid solution, but the outer diameter near the end face of the optical fiber becomes smaller with the processing time.

When the optical fiber having such a structure is used as it is, for example, when molten glass or the like is adhered to the concave portion of the etched optical fiber to form a microlens, which is used for coupling a light source or the like. (For example, JP-A-3-163406), there is no problem in reducing the outer diameter of the end face of the optical fiber. However, when the optical fiber is used without changing the outer diameter, the etched optical fiber used for coupling is used. When it is attached to the ferrule to reinforce, a gap is formed between the outer diameter of the etching optical fiber and the inner diameter of the ferrule, and it is difficult to fix the etching optical fiber in a stable and concentric state. Further, when the clad portion of the end face of the optical fiber is used as the adhesive fixing face, if the outer periphery of the optical fiber is etched and the contact area of the end face portion becomes small, the adhesive strength becomes poor.

As a method of etching only the end face portion in order to solve such a problem, a method of coating only the end face on the cylindrical side surface of the optical fiber by coating a material inert to the etchant and immersing in the etchant. Can be considered. For example, if a silica-based optical fiber is to be etched with hydrofluoric acid, coating the side of the optical fiber cylinder with polychlorinated biphenyl or lead means that only the end face of the optical fiber will be etched when immersed in a hydrofluoric acid solution. Become. However, this method has a problem that the process of coating only the side surface of the cylinder is not easy except for the end surface of the optical fiber, and the number of steps is increased as a whole.

[0005]

In order to solve these problems, the present invention provides a method and an apparatus for processing an end face of an optical fiber used in an optical connecting element, wherein the end face of the optical fiber is on the liquid surface of an etching solution. After contacting, the optical fiber end surface is moved to a position slightly above the liquid surface of the etching solution, and only the end surface of the optical fiber is etched, and the contact state between the optical fiber end surface and the liquid surface of the etching solution is changed from the contact surface. Provided are an etching processing method and a processing apparatus for an end face of an optical fiber, which measures, detects, and controls reflected return light.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention, FIG. 1 is a schematic view of an apparatus of this embodiment, and FIG. 2 is a schematic view showing an etching process according to the present invention. In the drawings, the same members are designated by the same reference numerals, 1 is an optical fiber, 2 and 3 are holders for holding the optical fibers, 4 is an optical branching / coupling device, 5 is a light source, 6 is a light receiver,
7 is a controller, 8 is a fine movement stage, 10 is a substrate, 1
1 is an etching solution.

In the figure, an optical fiber 1 to be etched
Is set in a holder 2 for fixing an optical fiber, and the end of the optical fiber 1 opposite to the end face 1a to be etched is connected to an optical branching / coupling device 4 via an optical fiber holder 3. A light source 5 and a light receiver 6 are connected to the opposite ports of the optical branching / coupling device 4, respectively. Further, the detection value of the light receiver 6 is loaded into the control controller 7 in real time. The optical fiber holder 2 is fixed to the fine movement stage 8, and the fine movement stage 8 receives the signal from the controller 7 and moves along the guide 9 in the vertical direction. The substrate 10 on which the apparatus is installed preferably has a vibration-proof structure in order to avoid vibration of the liquid surface 11a of the hydrofluoric acid solution.

The light emitted from the light source 5 enters the optical fiber 1 through the optical branching coupler 4 and is output from the end face 1a. At this time, the reflected return light at the end face passes through the optical branching coupler 4. Is detected by the light receiver 6. The amount of reflection on the end surface 1a is determined by the difference in the refractive index of the reflection surface. Before the end face 1a of the optical fiber 1 to be etched comes into contact with the end face 11a of the hydrofluoric acid solution, the reflection is the reflection at the interface between the optical fiber and air.

As shown in FIG. 1, the fine movement stage 8 is gradually lowered so that the end face 1a of the optical fiber is at the liquid level 11 of the hydrofluoric acid solution.
2a, when the optical fiber end face 1a contacts the liquid surface 11a of the hydrofluoric acid solution as shown in FIG. 2B, the reflection surface of the optical fiber end face 1a is the boundary between the optical fiber and the hydrofluoric acid solution. It becomes a reflection on the surface. The reflectance R at the interface between two media having different refractive indices is calculated by the following equation, where n1 is the refractive index of the medium 1 and n2 is the refractive index of the medium 2.

R = ((n2-n1) / (n1 + n2)) ^{2 As} can be seen from this, the larger the difference in refractive index between the two media, the larger the amount of reflection. The refractive index of the core of the optical fiber, the air, and the hydrofluoric acid solution are about 1.46 to 1.5, respectively.
Since 1.00 and 1.33, the optical fiber end face 1a
When the liquid comes into contact with the liquid surface 11a of the hydrofluoric acid solution, the amount of reflected light detected by the light receiver 6 becomes small. When the amount of reflected light changes, the fine movement stage 8 stops descending, and the fine movement stage 8 is pulled up so that the position of the end face of the optical fiber is several μm above the stopped position. At this time, the optical fiber end face 1a
There is a slight difference in height between the position and the liquid surface 11a, but due to the surface tension of the liquid, the liquid surface is in contact with only the optical fiber end surface 1a as shown in FIG. 2 (c). If etching is performed for a required processing time in such a state, only the end face portion can be etched without impairing the outer diameter near the end face of the optical fiber.

Further, when the etching time is relatively long, the position of the optical fiber end face 1a is set to the liquid surface 11a.
Even if it is not placed at a position slightly pulled up from above, the entire end face of the optical fiber is etched, and the position of the end face naturally becomes higher than the liquid level.Therefore, depending on the etching amount, the position of the first end face of the optical fiber Should be selected.

In this way, the position of the end face of the optical fiber is slightly separated from the liquid surface, and the etching progresses in a state where the etching liquid is in contact with only the end face due to the surface tension. Only the end face can be etched.

[0013]

As described in detail above, according to the method and apparatus of the present invention, it is possible to fabricate an etching fiber having a uniform outer diameter, and it is not necessary to coat the side surface. Since the number of steps is small and can be easily manufactured, the contact of the etching liquid on the end surface of the optical fiber with the liquid surface of the etching liquid is controlled by using the reflected return light from the end surface, so strict positioning is required when setting the optical fiber in advance. It has advantages such as no work and easy work.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example device of the present invention.

FIG. 2 is a schematic view showing a process of etching according to the present invention.

FIG. 3 is a schematic view showing an etching process according to a conventional method.

FIG. 4 is a diagram showing changes in the outer circumference of an optical fiber due to a conventional etching process.

[Explanation of symbols]

 1 Optical fiber 2 Holder 3 Holder 4 Optical branching / coupling device 5 Light source 6 Light receiver 7 Controller 8 Fine movement stage 9 Guide 10 Substrate 11 Etching liquid

Claims (2)

[Claims] 1. A method for processing an end face of an optical fiber used for an optical connecting element, wherein the end face of the optical fiber is brought into contact with the liquid surface of the etching solution, and then the end face of the optical fiber is moved to a position slightly above the liquid surface of the etching solution. A method for processing an optical fiber end face, characterized in that only the end face of the optical fiber is etched and the contact state between the end face of the optical fiber and the liquid surface of the etching solution is detected by measuring the reflected return light from the contact face. 2. In an optical fiber end face processing apparatus used for an optical connecting element, after the optical fiber end face is brought into contact with the liquid surface of the etching solution, the optical fiber end face is moved to a position slightly above the liquid surface of the etching solution. A fine movement stage,
An apparatus for processing an optical fiber end face, comprising a mechanism for measuring a contact state between the end face of the optical fiber and a liquid surface of an etching solution by measuring reflected light from the contact face.