JPH07167664A - Optical waveguide device - Google Patents

Abstract

PURPOSE:To obtain an optical waveguide device which is so designed as to attain improvement in a light radiation loss at an inputoutput part for a spiral main waveguide and also a mutual crosstalk characteristic of optical waveguides. CONSTITUTION:A spiral main waveguide 11 is formed of continued semicircles drawn around a first center O1 and a second center O2 so set as to correspond to a diametric line. A third center O3 is set at a distance of R11 from a point P6 which is an end part of the innermost circumference of this waveguide 11. A first curved waveguide 12 is formed by drawing a circular arc of a radius R11 in the sphere of a central angle 225 deg. around the third center, and a circular arc of the radius R11 around a fourth center O4 located at a distance R11 from a point P13 being a point of intersection of a line intersecting the diametric line perpendicularly and passing through the second center O2 and of the innermost circumference of the main waveguide 11 is made continuous to the first curved waveguide 12, as a second curved waveguide 13, on a line drawn in parallel with the diametric line from the point P13. This waveguide is made to intersect the aforesaid main waveguide 11 perpendicularly and led outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device which is used, for example, as a sensing loop portion of an integrated optical gyro and has an improved structure for drawing out to the outside.

[0002]

2. Description of the Related Art For example, an optical fiber gyro has been developed as a moving body angular velocity detecting device used in a navigation system for a moving body such as an automobile. In this case, the smaller the size of the optical fiber gyro, the wider the range of application thereof, such as automobiles. For example, an optical integrated circuit disclosed in Japanese Patent Laid-Open No. 64-64283 is proposed. .

However, in such an optical integrated circuit, with respect to the spiral optical waveguide relating to the detection of the angular velocity,
In particular, the specific structure of the innermost peripheral portion has not been examined. In the innermost circumference of this spiral waveguide, it is necessary to lead the tip to the outside by intersecting the spiral portion of the waveguide, but to reduce the loss due to bending of the optical waveguide. , There is a trade-off relationship between increasing the curvature of the innermost circumference and increasing the crossing angle with other waveguides (spiral parts) when the optical waveguide is pulled out to the outside. The composition has not been clarified.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in particular, in the lead-out portion from the spiral optical waveguide, the sensitivity can be surely improved and the waveguide can be surely improved. It is an object of the present invention to provide an optical waveguide device capable of effectively reducing the radiation loss due to the bending and further setting the crossing angle at another crossing portion surely large.

[0005]

An optical waveguide device according to the present invention is provided with a tip end of the innermost waveguide of a spiral main waveguide in which the waveguides are spirally formed at a predetermined pitch interval.
A first curved waveguide is continuously formed for extraction, and the first curved waveguide has a predetermined curvature in the same direction as the innermost waveguide of the spiral waveguide. Composed. A second curved waveguide is continuously formed at the tip of the first curved waveguide, and the second curved waveguide has a curvature in a direction opposite to that of the first curved waveguide. The straight line portion continuous with the second curved waveguide intersects the spiral waveguide and is led to the outside.

[0006]

In the optical waveguide device configured as described above, for example, the curvature of the first and second curved waveguides is 1/2 ^{(1 (1) of the} radius of curvature of the innermost peripheral portion of the spiral waveguide. ^By setting ^{/ 2)} , the bending radius of this portion can be set to be sufficiently large, and the extension line of the second curved waveguide can be configured to intersect the spiral waveguide at, for example, 90 °. This is made possible, and the radiation loss of light can be sufficiently reduced as well as the sensitivity is improved, and the angular velocity sensor of the moving body can be configured with high accuracy and high sensitivity.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a planar configuration of the optical waveguide device. A spiral main waveguide 11 in which the optical waveguide is formed into a loop by continuous circles, and a first main waveguide 11 continuous to the innermost peripheral portion of the main waveguide 11 are shown. The curved waveguide 12 and a second curved waveguide 13 which is a continuation of the first curved waveguide 12 are further provided. A first lead-out path 14 is formed at the tip of the outermost loop of the spiral main waveguide 11 so as to extend in the tangential direction of this loop, and a straight line is formed at the tip of the second curved waveguide 13. The second lead-out path 15 is formed so as to be extended to the outside, and the second lead-out path 15 intersects the spiral main waveguide 11 at a right angle (90 °) and is led out to the outside.

The manufacturing procedure of the optical waveguide device having such a structure will be described as follows. First, in order to form the spiral main waveguide 11,
From the point P1 on the diameter line A to the point P centering on the center O1 of the
Draw a radius R1 up to 7. Next, a semicircle having a radius R2 is drawn from the point P7 to the point P2 with the second center O2 separated by a distance d (mm) from the center O1 as the center. Therefore, the radius R2 in this case is set to a value smaller than the radius R1 by d (mm), the interval between the points P1 and P2 is set to 2d (mm), and this is the pitch interval of each loop.

Then, the points P2 to P8 are centered around the point O1.
Draw a semi-circle with radius R3 up to point P centered on point O2
Draw a semicircle with radius R4 from 8 to point P3. After that, similarly, draw a semicircle with radius R5 from P3 to point P9 centering on the point O1.
A semicircle of radius R6 is drawn from point P9 to point P4 centering on point O2, and a semicircle of radius R7 is drawn from point P4 to point P10 about point O1. Then, draw a semicircle of radius R8 from point P10 to point P5 centering on point O2, draw a semicircle of radius R9 from point P5 to point P11 centering on point O1, and finally draw point P11 centering on point O2. The spiral main waveguide 11 is formed by drawing a semicircle with a radius R10 from the point P6 to the point P6.

Next, a diameter line A connecting the centers O1 and O2
On the top of the loop, the point O3 at a distance R11 from the point P6 at the innermost circumference of the loop
A third center is set at, and a circular arc having a radius R11 is drawn within the range of the center angle of 225 ° from the point P6 to the point P12 with the third center O3 as the center. In this state, a center line is drawn parallel to the line A passing through the centers O1 to O3 and passing through the center O2 and passing through an intersection point P13 intersecting with the semicircle having the radius R10.
A fourth center O4 is set at a distance R11 from 13. Then, an arc having a radius R11 is drawn within a range of a central angle of 45 ° from the point P12 to the point P13 with the center O4 as the center. After that, on the extension of the straight line from the second center O2 to the point P13,
Draw a straight line from the point P13 to the intersection R14 with the semicircle having the radius R2, and then extend this straight line to P16 for the second derivation path.
Allow 15 to form. Further, the first lead-out path 14 is formed by extending from the point P1 which is the starting point of the spiral main waveguide 11 to the point P15 in parallel with the second lead-out path 15.

In a curved waveguide having a curvature like the spiral main waveguide 11, the larger the radius of curvature, the smaller the loss for the light wave propagating in the optical waveguide. Here, in the waveguide device shown in FIG. 1, a waveguide having a radius R11 having the smallest radius of curvature will be focused on and described in detail below.

FIG. 2 is a view for explaining the essence of the optical waveguide device configured as described above, and particularly shows the first curved waveguide 12 and the second curved waveguide 13 parts. The first curved waveguide 12 is constituted by an arc having a radius R11 formed continuously from a semicircle having a radius R10 at the innermost circumference of the spiral main waveguide 11, and at this time, the radius R
To guide the waveguide to the outside by making it orthogonal to the ten semicircles, that is, at the point P13, the two waveguides are made to be orthogonal, and the first and second curved waveguides for guiding this are provided.
In order to make the radii of the 12 and 13 arcs as large as possible, the radii of the two small circles centered on the points O3 and O4 must be made equal.

The reason is that if the radius of the circle centered on the third center O3 is made larger than this condition, the radius of the circle centered on the fourth center O4 becomes larger than the condition shown here. It gets smaller. This condition is expressed by the following equation, as is clear from the figure.

[0014]

[Equation 1] Further, when the optical waveguide is guided from the inside of the spiral main waveguide 11 to the outside, the light wave propagating in one of the waveguides leaks to the other waveguide, that is, the so-called crosstalk is minimized under the condition that two crossings are crossed. That is, the waveguides are orthogonal. Therefore, in this example, the two optical waveguides are set to intersect each other at a relationship of 90 ° at the point P13.

As described above, the spiral main waveguide 11
By setting the radius R11 of the smallest circular arc inside of the above to the relationship as shown in the above equation, the radiation loss of the propagating light wave caused by the bending of the optical waveguide is minimized, and the internal optical waveguide is When leading out to the outside of the loop portion, the crossing angle between the optical waveguides can be set to the orthogonal relationship which is the condition of the smallest crosstalk.

In this embodiment, the first and second derivation paths which are the input / output terminals for the spiral main waveguide 11 are provided.
Although 14 and 15 are set at a large interval, if configured as shown in FIG. 3, the first and second waveguides 14 and 15 that are the input / output ends can be set at a small interval. .

That is, a center line passing through the point P14 is formed in parallel with the center line passing through the point P13 and the fourth center O4, and the fifth center O is located on the center line at a distance R11 from the point P14.
Set 5. An arc of radius R11 is drawn from the point P14 to the point P17 with the central angle α around the center O5. Also,
An arc of radius R12 is drawn from the point P1 to the point P15 with the central angle α around the second center O2. And the fifth center O5
The first lead-out path 14 is formed by drawing a straight line from the point P17 to the point P15 at a distance w (mm) from the point P17 on the straight line passing through the point P17.

With this structure, the distance between the input and output ends of the first and second outlet paths 14 and 15 can be set to an arbitrary distance w.
And the condition of the angle α at this time is as follows.

[0019]

[Equation 2] It should be noted that, in the embodiment, it is described that the optical waveguide is formed as a continuous arc. However, in this embodiment, since the basic purpose is to reduce the propagation loss for the light wave propagating in the spiral optical waveguide, within the range where the loss can be ignored, the middle line of the ellipse or circle, or the straight line The optical waveguide may be formed as a part of the continuity.

[0020]

As described above, according to the optical waveguide device of the present invention, it is possible to surely improve the sensitivity, particularly in the portion of the loop-shaped optical waveguide having the spiral structure, and to improve the sensitivity. It is possible to effectively reduce the radiation loss due to bending, and the crossing angle can be surely set to be large at the crossing part of the other waveguides, so that an optical transmission line having good light propagation characteristics can be obtained. .

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration of an optical waveguide device according to an embodiment of the present invention in a planar development.

FIG. 2 is a diagram for explaining an essential operation of the above embodiment.

FIG. 3 is a diagram illustrating a second embodiment of the present invention.

[Explanation of symbols]

11 ... Spiral main waveguide, 12 ... First curved waveguide, 13
... second curved waveguide, 14 ... first derivation path, 15 ... second derivation path.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G02B 6/122

Claims (2)

[Claims] 1. A spiral main waveguide in which a waveguide is formed in a spiral shape at a predetermined pitch, and a waveguide at the innermost periphery formed continuously with the tip of the innermost waveguide of the main waveguide. A first curved waveguide having a predetermined curvature in the same direction as the first curved waveguide and a first curved waveguide formed continuously at the tip of the first curved waveguide, and having a curvature in the opposite direction to the first waveguide. An optical waveguide device comprising: a second curved waveguide having the second curved waveguide, wherein a straight line portion continuous to the second curved waveguide intersects the spiral waveguide and is led out to the outside. . 2. The curvature of the first and second curved waveguides is set to be approximately 1/2 ^{(1/2) of the} radius of curvature of the innermost peripheral portion of the spiral waveguide. Characterized optical waveguide device.