JP2971237B2 - Optical fiber end face processing method and processing apparatus - Google Patents

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 connection element, and more particularly, to a method in which an optical fiber core face is located inside an optical fiber clad end face to be a connection face with an optical waveguide. The present invention relates to a method and an apparatus for etching an end face of an optical fiber 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 and etching with hydrofluoric acid (for example, Japanese Patent Laid-Open No. 163406/1991). However, the so-called ion beam method, in which a solid material is subjected to ion bombardment in a vacuum to scatter surface atoms, requires large-scale equipment and high processing costs. Further, since the etching speed is low, it takes time to process. In addition, in the case of etching with hydrofluoric acid, since the end of the optical fiber is only immersed in a 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 simultaneously with the end face, as well as the outer periphery of the portion immersed in hydrofluoric acid. 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 optical fiber end face becomes smaller with the processing time.

When an optical fiber having such a structure is used as it is, for example, when a molten glass or the like is attached to a concave portion of an etched optical fiber to form a microlens and 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 at the end face of the optical fiber, but when used without changing the outer diameter of the optical fiber, an etched optical fiber used for coupling is used. When mounting the ferrule to reinforce the ferrule, 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 optical fiber in a state where it is stable and concentric. Further, when the clad portion of the end face of the optical fiber is used as the bonding and fixing surface, the outer periphery of the optical fiber is etched, and if the contact area of the end face portion is reduced, the bonding strength is deteriorated.

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

[0005]

SUMMARY OF THE INVENTION In order to solve these problems, the present invention relates to a method and an apparatus for processing an end face of an optical fiber used for an optical connection element. Then, the end face of the optical fiber is moved to a position slightly higher than the liquid level of the etching solution, and 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 level of the etching solution is changed from the contact surface. Provided is an optical fiber end face etching method and apparatus for measuring, detecting, and controlling 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 the present invention, and FIG. 2 is a schematic view showing an etching process according to the present invention. In the drawings, the same members are denoted by the same reference numerals, 1 is an optical fiber, 2 and 3 are holders for holding the optical fiber, 4 is an optical branching coupler, 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 coupler 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 coupler 4, respectively. Further, the detection value of the light receiver 6 is taken into the control controller 7 in real time. The optical fiber holder 2 is fixed to a fine movement stage 8, and the fine movement stage 8 receives a signal from the controller 7 and moves in a vertical direction along a guide 9. The substrate 10 on which the apparatus is installed preferably has an anti-vibration 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 via the optical branching coupler 4 and exits from the end face 1a. At this time, the return light reflected at the end face is transmitted through the optical branching coupler 4 And is detected by the light receiver 6. The amount of reflection at 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 contacts the end face 11a of the hydrofluoric acid solution, the reflection is a reflection at the interface between the optical fiber and air.

As shown in FIG. 1, the fine movement stage 8 is gradually lowered, and the optical fiber end face 1a is brought into contact with the liquid surface 11 of the hydrofluoric acid solution.
When the optical fiber end face 1a comes into contact with the liquid surface 11a of the hydrofluoric acid solution as shown in FIG. 2B, the reflection surface of the optical fiber end face 1a becomes the boundary between the optical fiber and the hydrofluoric acid solution. Reflection on the surface. The reflectance R at the interface between two media having different refractive indices is obtained 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 = ((n 2 −n 1) / (n 1 + n 2)) ^{2 As} can be seen, the greater the difference between the refractive indices of the two media, the greater the amount of reflection. The refractive indices of the core of the optical fiber, air, and hydrofluoric acid solution are about 1.46 to 1.5, respectively.
1.00, 1.33 or more, the optical fiber end face 1a
When light 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 smaller. When the amount of reflected light changes, the movement of the fine movement stage 8 is stopped, and the fine movement stage 8 is raised so that the position of the end face of the optical fiber is several μm higher than 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 comes into contact only with the optical fiber end surface 1a as shown in FIG. 2 (c). In such a state, if etching is performed for a required processing time, only the end face can be etched without damaging the outer diameter near the end face of the optical fiber.

When the etching time is relatively long, the position of the optical fiber end face 1a is changed to the liquid level 11a.
Even if it is not placed at a position slightly raised from the position, the entire end face of the optical fiber is etched and the position of the end face naturally becomes higher than the liquid level. You just have to select

As described above, the position of the end face of the optical fiber is slightly separated from the liquid surface, and the etching proceeds with only the end face in contact with the etching liquid due to the surface tension. Etching of only the end face can be performed.

[0013]

As described in detail above, according to the method and apparatus of the present invention, it is possible to produce an etched fiber having a uniform outer diameter of an optical fiber, and it is not necessary to coat the side surface. Since the contact of the etchant on the optical fiber end surface with the liquid surface is controlled using the reflected light reflected from the end surface, strict positioning is required when setting the optical fiber in advance. There is an advantage that the work is simple because there is no.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an etching process according to the present invention.

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Holder 3 Holder 4 Optical branching coupler 5 Light source 6 Receiver 7 Controller 8 Fine movement stage 9 Guide 10 Substrate 11 Etching liquid

Claims (2)

(57) [Claims] In a method for processing an end face of an optical fiber used for an optical connection element, an end face of an optical fiber is brought into contact with a liquid surface of an etching solution, and then the end surface of the optical fiber is moved to a position slightly higher than the liquid surface of the etching solution. A method of processing an end face of an optical fiber, wherein only the end face of the optical fiber is etched, and the state of contact between the end face of the optical fiber and the liquid surface of the etching solution is detected by measuring reflected light reflected from the contact surface. 2. An apparatus for processing an end face of an optical fiber used for an optical connection element, wherein the end face of the optical fiber is brought into contact with a liquid surface of the etching solution, and then the end surface of the optical fiber is moved to a position slightly higher than the liquid surface of the etching solution. A fine movement stage,
A mechanism for measuring the state of contact between the optical fiber end face and the liquid surface of the etching solution by measuring reflected return light from the contact face and detecting the contact state.