JP2002071976A - Method of working optical fiber having wedge type lens and working device used in it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber having a lens which is small in dispersion, has high optical coupling efficiency, moreover has excellent precision and has an excellent yield. SOLUTION: In the optical fiber having a lens at the end part in which the lens is formed, light is made incident from the opposite end of the lens part of the optical fiber, and the lens of the optical fiber is worked by polishing or the like while measuring the light emitting pattern of incident light or reflected return light from the lens part.

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 optical fiber with a lens used for optical coupling between a light emitting source used for optical communication and an optical fiber.

[0002]

2. Description of the Related Art As a light emitting source for optical communication, a laser diode (hereinafter referred to as an LD), a light emitting diode or the like is used. When the light emitted from the LD 12 is coupled to the optical fiber 13 with a small loss as shown in FIG. 5, a tip-shaped fiber in which the tip of the optical fiber 13 is processed into a lens shape, an optical fiber with a wedge lens, or the like is used.

As shown in FIG. 6A, a conventional method for processing an optical fiber with a wedge-shaped lens is to hold the optical fiber 13 on an optical fiber holding jig 15,
After making the tip of the wedge into a wedge shape, the tip is melted by heat as shown in FIG. 6 (b) or is rounded by polishing as shown in FIG. 6 (c) (see US Pat. No. 3,910,677). ).

The end face of the optical fiber is polished from one side by mechanical grinding and mechanical polishing from one side of the optical fiber. After the fiber is polished to the center of the fiber, it is rotated by 180 ° and ground from the opposite direction to obtain a wedge-shaped fiber. And then polishing the tip to form a cylindrical optical fiber with a lens (US Pat. No. 5,845,502).
No. 4).

[0005]

However, in the conventional method of processing an optical fiber with a lens described above, the lens portion at the tip of the optical fiber is polished by using a grindstone or the like based on the outer diameter of the optical fiber. Is made,
As shown in FIG. 7, there is a problem that the center of the core 13a of the optical fiber 13 is deviated from the center of the lens portion 13b. When light is incident on the lens portion 13b of the optical fiber 13, the light is not incident straight, and However, there is a problem that the optical coupling efficiency is significantly reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a method of processing an optical fiber with a lens having a wedge-shaped lens at the tip thereof is provided.
Light is incident from the rear end of the optical fiber, and while measuring the light emission pattern and / or the reflected return light from the front end of the optical fiber, the incident light exits from the front end of the optical fiber. It is characterized by processing.

In a device for processing an optical fiber with a lens having a wedge-shaped lens at the distal end, a polishing or grinding means for processing the distal end of the optical fiber, a light source for inputting light from the rear end of the optical fiber, and a light source. It is characterized by comprising a measuring device for a light emission pattern emitted from the fiber tip and / or a device for measuring the amount of reflected return light from the optical fiber tip.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a method for processing a lens of an optical fiber with a lens according to an embodiment of the present invention. The apparatus for processing an optical fiber with a lens includes a polishing machine 1 for processing a lens shape, a light source 2 and a camera 3 for measuring a light emission pattern. The wavelength of the light used for the light source 2 is preferably the wavelength when the fiber with a wedge-shaped lens is actually used, but may be any other wavelength as long as the light pattern can be measured. Further, since the wavelength actually used is longer than the visible light, it is preferable to use an imaging tube for infrared light as the measurement camera 3.

Using this apparatus, light from the light source 2 is incident from the rear end of the optical fiber 4, and the tip of the optical fiber 4 is polished by the polishing machine 1 while the light emission pattern from the tip is measured by the measuring camera 3. .

First, as shown in FIG. 2 (a), after polishing one surface of the wedge-shaped optical fiber 4, the light pattern 5 is measured in a direction deviated from the center of the measuring system on the extension of the optical fiber 4. .

Next, as shown in FIG. 2 (b), when processing the opposite surface, as the polishing progresses, the light pattern 6 transmitted through the lens-shaped portion from the light source 2 and emitted to the center of the measurement system. On the other hand, when the center of the light pattern 7 coincides with the center of the measurement system as shown in FIG. If the polishing is further continued, the center of the light pattern 8 passes through the center of the measurement system as shown in FIG.

Therefore, by polishing this end while measuring the light pattern when polishing the optical fiber 4, the polishing is performed when the center of the light pattern 7 coincides with the measurement center as shown in FIG. 2 (c). If stopped, it is possible to prevent the tip of the optical fiber 4 from being shifted from the apex of the tip lens portion.

After that, the tip is melted by heat, or rounded by polishing or the like to form a lens shape.

FIG. 3 is a view showing a method of processing a lens of an optical fiber with a lens according to another embodiment of the present invention. The apparatus for processing an optical fiber with a lens according to the present embodiment includes a polishing machine 1 for processing a lens shape, a light source 2, a reflection return light quantity measuring device 9,
It comprises an optical splitter 10. The reflected return light amount measuring device 9 is a measuring device for measuring the light amount.

Light from the light source 2 passes through the optical splitter 10, and the split light enters the rear end of the optical fiber 4 and is reflected at the front end for lens processing. The reflected light passes through the optical splitter 10 again, and the split light is reflected back to the light quantity measuring device 9.
And measure the amount of reflected and returned light.

In this embodiment, the tip of the optical fiber 4 is polished while measuring the amount of reflected return light.

First, the wedge-shaped one surface at the tip of the optical fiber 4 is polished, and then the amount of reflected light returning from the end face of the fiber processing portion when the opposite side of the wedge is polished changes as shown in FIG.
This is because the light reflected on one side of the wedge is further reflected on the opposite side and returns to the optical fiber, so if the opposite side starts to be polished, the reflected return light increases, and the wedge at the tip moves relative to the core. When it becomes symmetrical, it reaches a peak 11, and thereafter the amount of returning light decreases. Therefore, the tip shape becomes the optimum position when the amount of returning light reaches the peak 11.

As described above, the tip is polished while measuring the time change of the amount of reflected return light, and the polishing is finished at a position where the amount of reflected return light increases and the amount of change becomes almost zero. Become. At that time, the center of the light pattern coincides with the center of measurement, and the apex deviation from the core of the fiber is eliminated.

After that, the tip is melted by heat or subjected to rounding using polishing or the like to form a lens shape.

In the above-mentioned processing method, the polishing machine 1 for processing the wedge-shaped lens portion performs polishing by pressing the optical fiber 4 while supplying abrasive grains made of diamond onto the rotating disk. The same polishing machine is used for processing. The shape of the wedge-shaped lens portion is such that the angle of the wedge is 50 to 120 ° and the radius of curvature of the tip R is 3 to 15 μm.
m is preferable.

[0022]

EXAMPLE An optical coupling efficiency of an optical fiber with a wedge lens was measured. The intensity distribution (mode field) pattern of the light emitted from the LD 12 has an elliptical shape with an aspect ratio of 4: 1. The optical fiber has a mode field diameter of 6.
A 0 μm circularly symmetric single mode optical fiber 13 was used.

A sample prepared by measuring the amount of reflected return light using the apparatus shown in FIG. 3 by the processing method of the present invention and a polishing time as shown in FIG. The binding efficiencies were measured using samples prepared under control and compared. The measurement was performed for each of ten samples, and the measurement was performed using the same LD.

As shown in Table 1, the average value of the coupling efficiency of the embodiment of the present invention in which the amount of reflected return light was measured was 1.
Since it is 5% higher and the standard deviation is small, it can be seen that processing variations can be reduced.

[0025]

[Table 1]

[0026]

According to the present invention, in a method of processing an optical fiber with a lens having a wedge-shaped lens at the tip, light is incident from the rear end of the optical fiber and the incident light is emitted from the tip of the optical fiber. And / or by subjecting the tip of the optical fiber to lens processing by polishing or the like while measuring the reflected return light from the tip of the optical fiber. In addition, it is possible to provide an optical fiber with a lens with high accuracy and excellent yield.

[Brief description of the drawings]

FIG. 1 is a view showing an apparatus for processing an optical fiber with a wedge-shaped lens according to the present invention.

2 (a) to 2 (d) are diagrams showing a change in an optical pattern in a processing method using the apparatus of FIG.

FIG. 3 is a view showing another embodiment of the processing device for an optical fiber with a wedge-shaped lens according to the present invention.

FIG. 4 is a diagram showing a change in the amount of reflected return light in a processing method using the apparatus of FIG. 3;

FIG. 5 is a diagram for explaining the coupling efficiency between an optical fiber and an LD.

FIGS. 6A to 6D are views showing a conventional method for processing an optical fiber with a lens.

FIG. 7 is a diagram for explaining a problem in a conventional optical fiber with a lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 16 Polisher 2 Light source 3 Light emission pattern measuring camera 4, 13 Optical fiber 5, 6, 7, 8 Light pattern 9 Reflection return light measuring device 10 Optical splitter 11 Peak 12 LD 15 Optical fiber holding jig

Claims (2)

[Claims] 1. A method for processing an optical fiber with a lens having a wedge-shaped lens formed at the end thereof, wherein light is incident from the rear end of the optical fiber, and the incident light is emitted from the optical fiber end and / or the optical fiber end. A method of processing an optical fiber with a wedge-shaped lens, characterized in that a lens processing is performed on the tip of the optical fiber by polishing or the like while measuring reflected return light from the lens. 2. An apparatus for processing an optical fiber with a lens having a wedge-shaped lens at the tip, a polishing or grinding means for processing the tip of the optical fiber, a light source for inputting light from the rear end of the optical fiber, and a light source. An apparatus for processing an optical fiber with a wedge-shaped lens, comprising: a measuring device for a light emission pattern emitted from the tip of the fiber and / or a device for measuring the amount of reflected return light from the tip of the optical fiber.