JP2871444B2 - Method and apparatus for processing micro concave portion of optical waveguide - 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 manufacturing an optical waveguide having a coupling portion with high precision.
In particular, the present invention relates to a technique for facilitating connection between an optical waveguide and an optical component or an optical fiber.

[0002]

2. Description of the Related Art An optical fiber as an optical transmission line is widely used not only for public line communication but also for data transmission, a dedicated line, and an information transmission medium for vehicles and aircraft. On the other hand, optical waveguides having functions such as light branching, demultiplexing, coupling, modulation, and switching are also used in various fields.

[0003] At this time, what is important is a coupling loss at the time of connection between the optical waveguide and another optical component such as an optical fiber. Since the coupling loss at the connection point has a large effect on the system, it is desirable to reduce the coupling loss as much as possible.

[0004] In addition, cost is important for the wide use of optical waveguides in various fields, and it is also important to easily connect optical waveguides to other optical components such as optical fibers. Come.

To solve the above problems, (1) Japanese Patent Application Laid-Open No. 57-141610 discloses a method of fusion splicing an optical waveguide and an optical fiber by using a laser beam. Method of coupling optical waveguide and optical fiber using block having coupling groove (3) JP-A-2-33105 discloses a method of forming a hole in a core portion of an optical waveguide with a laser.

In order to solve the above-mentioned problems (1) to (3), Japanese Patent Laid-Open No. 5-1134 has been disclosed.
Discloses a method and an apparatus for forming a coupling hole in a core portion of an optical waveguide using a processing jig.

[0007]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 5-1 has been disclosed.
No. 1134 discloses an example in which a microdrill, a micro end mill, and an electrodeposition grindstone are used as the processing jig. However, in these jigs, the tip of the jig must be precisely processed to about 10 μm in order to obtain a coupling hole having a desired shape and size. In addition, when the substrate on which the optical waveguide is formed is a brittle material such as a quartz substrate or a glass substrate, microcracks are generated in the processed holes, which may adversely affect optical characteristics and reliability.

Accordingly, an object of the present invention is to provide a method and an apparatus for processing a minute concave portion of an optical waveguide which solves the above problems.

Accordingly, the present invention provides an optical waveguide in which a portion having a higher refractive index than a transparent substrate is formed in a desired pattern.
, The pressure of the indenter heating at least the tip portion of the conical shape, the core portion of the waveguide which is exposed to the substrate edge
And forming a concave portion by transferring the shape of the tip portion of the indenter.

[0010] Further, there is provided a processing apparatus for forming a minute concave portion in the core of the optical waveguide for connecting the core of the optical waveguide and the optical fiber, wherein (a) an indenter, (b) a mechanism for heating the indenter, ) A mechanism for linearly moving the indenter, (d) a mechanism for applying a load to the indenter, (e) a stage having a function of fixing the optical waveguide substrate and finely adjusting the position thereof, and (f) a core portion of the optical waveguide. Light microscope for observing
(G) a slider mechanism for moving the stage between the processing section described in (a) to (d) and the observation section described in (f), and (h) illumination for illuminating the waveguide. An apparatus, (i) a minute displacement meter for monitoring displacement of an indenter, and an apparatus for processing a minute concave portion of an optical waveguide comprising the above.

[0011]

Only the indenter having the desired shape is locally heated and brought into contact with the core portion of the optical waveguide so that this portion exhibits a ductile behavior, and the indenter is further press-fitted to form a concave shape. . Therefore, it is possible to form a concave portion having a shape in a range where the indenter can be processed.

Furthermore, since the core portion forms the concave shape in a state where the core portion exhibits ductile behavior, the occurrence of the micro crack can be prevented.

[0013]

【Example】

(Embodiment 1) First, a processing method of the present invention will be described with reference to FIG. Stage 4 of the optical waveguide substrate 70
Fix to 0. The stage is moved to a microscope observation position. The center position of the core portion of the optical waveguide is determined by illuminating transmitted light from an opposite surface to a target surface using an illumination device (not shown) or the like, and performing image processing on an observation image of the optical waveguide. , The center position of the core part is obtained.

The stage 40 is adjusted so that the obtained center position of the core portion coincides with the center 46 of the observation position. When the adjustment is completed, the stage 40 is moved to the processing position 45. This processing position center is located at a position equivalent to the observation position center, and the axis of the indenter coincides with the processing position center.
(See Fig. 5)

Next, a processing method will be described with reference to FIG. The tip of the indenter 11 is heated, an appropriate weight 19 is placed on the weight base 14, and the indenter is gradually lowered. When the indenter 11 comes into contact with the optical waveguide substrate 70, the position of the indenter 11 can be determined by the minute displacement meter 20. Further, the indenter is pressed into the core portion by the weight of the weight. Hold that state for a certain time. Thereafter, by removing the indenter, a minute concave portion 72 to which the shape of the indenter is transferred is formed.

The indenter shape is the shape 7 of the tip of the optical fiber 73.
Although it is determined by 4, the conical projection is easily formed by the etching method. The material must be harder than the glass substrate, and diamond, corundum (sapphire, ruby), cemented carbide, or the like is used.

The method of heating the indenter includes radiant heating by an external heater, heating by an embedded heater, high-frequency heating, and heating by a burner.

The conditions for press-fitting differ depending on the type of glass, the material and the shape of the indenter. The range of each conceivable condition is as follows. (1) Weight: 5 to 100 g (2) Pushing speed: 1 to 10 μm / sec. (3) Retention time: 1 to 10 sec. (4) Indenter temperature: 250 to 1000 ° C. When the temperature of the indenter is fixed, the indentation depth of the indenter is determined by the weight of the weight. Note that the temperature of the indenter is
1 and a calibration curve is prepared and used from the set temperature of the heater and the temperature of the tip of the indenter.

Next, a specific example will be described. First, the used optical waveguide will be described. This is manufactured using a borosilicate glass substrate 70 by an electric field application ion exchange method. The formed waveguide 71 is a single-mode waveguide having a diameter of 10 μm and an embedded depth at the center of 10 μm. The pattern is
This is a 1 × 4 branch pattern. (See Fig. 4)

Next, an optical fiber having a convex portion corresponding to the concave portion is processed. A tip of an optical fiber 73 (for example, a single mode fiber manufactured by Sumitomo Electric Industries, Ltd.) is treated with a mixed etching solution of hydrofluoric acid and ammonium fluoride (HF: 4.5% by weight, NH ₄ F: 36.4% by weight, liquid temperature). : 50 ° C) 6
After immersion for 0 minutes, the core portion becomes conical (vertical angle: 105
°, height: 7 μm).

The processing conditions selected at this time are as follows. (1) Weight: 30 g (2) Pushing speed: 2 μm / sec. (3) Retention time: 2 sec. (4) Indenter temperature: 350 ° C

With the above processing method, the apex angle is about 10
At 5 °, a conical recess 72 having a depth of about 7 μm could be formed. At this time, no crack was observed in this concave portion.

When the optical waveguide having a concave shape and the optical fiber having a convex shape processed as described above are connected by using the concave and convex portions, it is assumed that there is an axis deviation of, for example, about 1 to 2 μm. Also, it was found that the connection can be accurately performed by the self-centering action of the uneven shape. (See Fig. 3)

Comparative Example 1 In Comparative Example 1, the indenter was pressed into borosilicate glass without heating. As a result, in this case, many cracks occurred inside and around the conical indentation.

(Embodiment 2) Next, a processing apparatus will be described with reference to the drawings. This processing device (Fig. 1)
It comprises a processing part, an observation part, a stage part, a slider part for moving the stage between the processing part and the observation part, and a base for supporting the whole. An optical microscope is attached to the observation unit. Although not shown, there is an illumination device for observing the core of the optical waveguide.

FIG. 5 shows the stage section 40 and the slider section 44. The stage unit 40 includes a stage (41, 42) and a micrometer (not shown) in the X-axis and Y-axis directions for fine adjustment of the position for processing the concave portion.
There is. Further, there is a clamp mechanism 43 for fixing the optical waveguide substrate. In the processing section and the observation section, the center of the stage is adapted to coincide with the axis of the indenter and the optical axis of the microscope.
When the slider is moved in parallel by a later-described slider portion, the processing position coincides with the axis of the indenter.

FIG. 6 shows a processing portion. The processing unit includes an indenter 11, a heater unit 30 for heating the indenter, a stage 14 on which a weight is placed, a minute displacement meter 20, and a drive unit for vertically moving a part including the indenter. The indenter is attached to the tip of the shaft 12. The shaft is a linear guide 1
3, a stand 14 for mounting a weight is mounted on the side opposite to the indenter. A coil spring 15 is mounted between the linear guide 13 and the base 14. The linear guide 13 is fixed to the arm 10 protruding from the driving unit. At the tip of the arm, there is a stopper 16 for determining the lower limit position of the weight base. The stopper 16 is attached to the arm 10 via a stage 17 and a micrometer 18.

The indenter 11, the shaft 12, and the weight base 14 are
These weights are integrated with the coil spring 15.
It is supported by. The position at which the coil spring 15 contracts due to its own weight and is just in an equilibrium state is the lower limit position of the weight base. The position of the stopper 16 is adjusted so as not to fall below the lower limit position. In this state, the weight 19 is placed on the weight base, and when the indenter comes into contact with the workpiece and the position of the weight base comes to a position above the lower limit position, the weight of the weight is directly applied to the indenter. Will be.

Further, a small displacement gauge 20 for measuring the contact between the indenter and the workpiece and the depth of the indentation is attached to the arm 10. This fine displacement meter 20 also has a stage 22 and a micrometer 2 for fine adjustment.
3 is attached to the arm 10. The micro displacement meter 20 uses an electric micrometer probe 21.

The above-described linear guide 13, stopper 16,
The minute displacement meter 20 is fixed to the same arm 10 and moves. The shaft 12 with the indenter also moves as the arm 10 moves. However, when the tip of the indenter 11 comes into contact with the workpiece, the relative positional relationship between the weight base 14 and the micro displacement gauge 20 changes. The contact between the indenter and the workpiece can be sensed by monitoring the value of the scale of the minute displacement meter. The press-in depth of the indenter can be determined from the difference between the contact position and the end of press-fitting.

FIG. 7 shows the heater section 30. Indenter 1
The heater 30 for heating 1 is configured by winding a heating wire 31 around a stainless steel tube 32 via a heat insulating material 33. Although not shown, a thermocouple is provided for temperature control. Further, a mechanism 34 is attached to adjust the vertical position of the entire heater section.

The driving section comprises a stepping motor 51 and a ball screw 52. When the stepping motor 51 is rotated, the ball screw 52 is rotated, and the arm 10 is rotated.
The linear guide 53 to which is attached is moved up and down. The slider section 44 moves the stage between the processing section and the observation section.

[0033]

According to the present invention described above, the core portion of the optical waveguide formed on the glass substrate, which is a brittle material,
A conical minute concave portion can be formed without generating a crack. Furthermore, if this is combined with a fiber having a conical convex portion at the tip, a self-centering function works with the concave and convex shapes of each other, and optical connection can be easily performed.

For this reason, an expensive alignment device is not required,
Since the process is simple, the cost for connecting the optical waveguide and the fiber can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a micro-recess processing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a process of processing a minute concave portion of an optical waveguide according to the present invention.

FIG. 3 is a diagram illustrating a connection state between a minute concave portion of an optical waveguide manufactured according to the present invention and a convex portion of an optical fiber.

FIG. 4 is a diagram of a 1 × 4 optical waveguide and an optical fiber manufactured by the processing method of the present invention.

FIG. 5 is a view for explaining a stage section and a slider section of the micro-recess processing apparatus according to the present invention.

FIG. 6 is a view for explaining a processing section of the micro-recess processing apparatus according to the present invention.

FIG. 7 is a view for explaining a heater section of the minute recess processing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Arm 11 Indenter 12 Shaft 13 Linear guide 14 Weight stand 15 Coil spring 16 Stopper 17 Stopper fine adjustment stage 18 Stopper fine adjustment micrometer 19 Weight 20 Micro displacement gauge 21 Electric micrometer probe 22 Probe fine adjustment stage 23 Probe fine adjustment micrometer 30 Heater part 31 Heating wire heater 32 Stainless steel tube 33 Insulation material 34 Heater part vertical movement mechanism 40 (Sample fixing) stage 41 X-axis stage 42 Y-axis stage 43 (Sample fixing) clamp 44 Slider mechanism 45 Processing position origin 46 Observation position Origin 50 Base stand 51 Stepping motor 52 Ball screw 53 Linear guide 60 Optical microscope 70 Optical waveguide board 71 Optical waveguide 72 Micro concave portion of optical waveguide 73 Optical fiber 74 Optical fiber Part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Nishizawa 3-5-11, Doshomachi, Chuo-ku, Osaka-shi, Osaka Nippon Sheet Glass Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 6/13 G02B 6/30

Claims (2)

(57) [Claims] An indenter having at least a conical tip heated at an end portion of the light guide , the guide being exposed to an end of the substrate; A method of processing a minute concave portion of an optical waveguide , wherein the concave portion is formed by press-fitting into a core portion of a waveguide and transferring the shape of the tip portion of the indenter. 2. A processing apparatus for forming a minute concave portion in a core of an optical waveguide for connecting the core of the optical waveguide to an optical fiber, comprising: (a) an indenter, (b) a mechanism for heating the indenter,
(C) a mechanism for linearly moving the indenter, (d) a mechanism for applying a load to the indenter, (e) a stage having a function of fixing the optical waveguide substrate and fine-tuning the position thereof, and (f) a stage of the optical waveguide. An optical microscope for observing the core; (g) a slider mechanism for moving the stage between the processing section described in (a) to (d) and the observation section described in (f); An illumination device for illuminating said waveguide;
(I) A minute displacement meter for monitoring the displacement of an indenter, and a device for processing a minute concave portion of an optical waveguide comprising the above.