JPH0697295B2 - Optical connector manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical connector used for connecting a polarization maintaining fiber to an optical waveguide such as a semiconductor, LiNbO ₃ or silica.

(Prior art and problems) Conventionally, the connection between the optical waveguide such as semiconductor, LiNbO ₃ , and silica and the polarization-maintaining fiber is performed in order to align the main axes with each other.
As shown in the figure, the polarization maintaining fiber was rotated around the Z axis and the angle was adjusted while monitoring the polarization state of the light. That is, if the principal axes x'and y'of the optical waveguide and the principal axes x and y of the polarization maintaining fiber are aligned within an angle error of 5 °, the crosstalk cannot be suppressed to 20 dB or less.

Here, 1 is a polarization maintaining fiber, 2 is an optical waveguide, 3,
4 is a core, 5 is a stress applying part, and 6 is a clad.

However, the conventional method has drawbacks such that it is difficult to adjust the main axes of the polarization maintaining fiber and the optical waveguide, and an angular deviation occurs at the stage of fixing after the adjustment.

(Means for Solving Problems) The present invention realizes a compact and low-priced optical connector by automatically aligning the main axes of the polarization maintaining fiber and the optical waveguide.

The main feature of the present invention is that the flat surface of the optical fiber is exposed by etching, and the upper flat surface is bonded or pressure-bonded to the substrate to automatically adjust the axis, which is different from the conventional technique. .

(Embodiment) FIG. 1 is an embodiment of the present invention, in which 7 is a fiber having a flat surface by etching, 8 is a core, 9 is a stress applying portion, 10 is a Si substrate, and 11 is for crimping. It is a glass plate. An optical fiber used for the optical connector of FIG. 1 and a procedure for manufacturing the optical connector are shown below.

Fig. 2 is a diagram showing the fiber preform before drawing. 12 is a core glass made by flatly polishing both sides of an ordinary columnar preform, and 13 is a stress applying part in which fluorine is added to SiO _2. Glass, 14 is glass for a high etching rate part, which is obtained by polishing a base material obtained by adding B ₂ O ₃ to SiO ₂ in an amount of 15 mol% in a half-moon shape, and 15 is a quartz tube. Each glass was inserted into a quartz tube 15 as shown in FIG. 2, then heated to 2100 ° C. in an electric furnace and drawn.

FIG. 3 shows a cross-sectional view of the obtained fiber. Reference numeral 16 is a core, 17 is a stress applying portion, and 18 is a high etching rate portion.
As can be seen from FIG. 3, the flat surface of the produced fiber is retained.

Next, FIG. 4 shows the etching rates of various dopants added to the high etching rate part for hydrofluoric acid. For example, in the case of boron B, the difference in relative refractive index of the glass added with 15 mol% is | Δ | = 0.5%, so the etching rate for hydrofluoric acid is 5,000Å / sec. Since contrast the etching rate of SiO ₂ is a 220 Å / sec, in the case of the fiber of FIG. 3 is etched with hydrofluoric acid, as shown in FIG. 5, the high etch rate portion is etched SiO ₂ When reaching the flat surface, the etching rate rapidly decreases. Therefore, a fiber having excellent flatness can be obtained. In FIG. 5, 19 is a core, 20 is a stress applying portion, and 21 is a flat clad.

Next, FIG. 6 shows a manufacturing procedure of the Si substrate for disposing the high connector shown in FIG. First, a photoresist 23 is applied on the [110] surface of the Si substrate 22 (Fig. 6a), and exposed through a mask pattern corresponding to the major axis length of the flat fiber in Fig. 5, and then the photoresist is removed. (Fig. 6b).

Next, when Si is etched using KOH, the [111] plane is exposed as shown in FIG. 6c. The optical connector shown in FIG. 1 is manufactured by inserting three flat fibers into the substrate thus obtained and pressing them with a glass plate.

The main axis setting accuracy of this optical connector was Δθ2 °, and the crosstalk deterioration in the connection with the optical waveguide was R = 10 logsin ² Δθ-29 dB (1).

(Effects of the Invention) As described above, in the present invention, since the main axes of the polarization maintaining fiber and the optical waveguide are set automatically and with high accuracy, the performance of the optical connector for connecting the optical fiber and the optical waveguide is improved. However, there is an advantage that the price can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical connector according to the present invention, FIG. 2 is a diagram showing a cross section of a base material for producing an optical fiber used in the present invention, and FIG. FIG. 4 is a cross-sectional view of a fiber obtained by drawing a material, FIG. 4 is a view showing etching rates of various dopants with respect to hydrofluoric acid, FIG. 5 is a cross-sectional view when the fiber of FIG. 3 is etched, and FIG. FIG. 7 is a diagram showing a procedure for producing an optical connector substrate, and FIG. 7 is a diagram showing a conventional method for connecting a polarization maintaining fiber and an optical waveguide. 1 ... Polarization maintaining fiber, 2 ... Optical waveguide 3 ... Core, 4 ... Core 5 ... Stress applying part, 6 ... Clad 7 ... Flat fiber, 8 ... Core 9 ... Stress applying part, 10 …… Si substrate 11 …… Glass plate 12 …… Flat fiber glass 13 …… Stress applying part glass 14 …… High etching rate part glass 15 …… Quartz tube, 16 …… Core 17 …… Stress applying part 18 …… High etching rate part 19 …… Core, 20 …… Stress applying part 21 …… Flat clad, 22 …… Si substrate 23 …… Photoresist

Claims (4)

[Claims] 1. An optical fiber in which half-moon shaped high etching rate parts are arranged in the clads on both sides of the core, and flat surfaces of the high etching rate parts are arranged in parallel with each other facing the core side.
A method for manufacturing an optical connector, wherein etching is performed until a flat surface is exposed, and the flat surface is bonded or pressure-bonded to a substrate to adjust a direction of the substrate and a main axis of an optical fiber. 2. A large number of the fibers whose flat surfaces are exposed,
The optical connector manufacturing method according to claim 1, wherein the optical connectors are arranged in an array on the substrate. 3. B ₂ as a dopant for a high etching rate portion
The method for producing an optical connector according to claim 1, wherein O ₃ , P ₂ O ₅ , GeO ₂ , TiO ₂ , fluorine, or a combination thereof is used. 4. A stress applying portion having a thermal expansion coefficient different from that of the cladding in a cladding surrounded by flat surfaces on both sides of the core in a direction orthogonal to the high etching rate portions on both sides of the core. 2. The method for manufacturing the optical connector according to item 1.