JPS6319606A - Optical waveguide - Google Patents

Abstract

PURPOSE:To suppress crosstalk by shifting the intersection of the prolongations of the center lines of two input optical waveguides and the intersection of the prolongations of the center lines of two output waveguides from each other so that two vertexes formed of the center lines are superposed one over the other. CONSTITUTION:A two-input and two-output crossing type optical waveguide is so constituted that the angle theta of intersection is 5 deg., the width of the optical waveguide -2mum, the refractive index of the clads 3 3.15, and the refractive index of the optical waveguide 3.3. When light which has -1.3mum wavelength and a -2mum is incident on one input optical waveguide 1-1 of this crossing type optical waveguide, the power ratios of light beams projected from the two output optical waveguides 2-1 and 2-2 are nearly equal to each other. On the other hand, the intersections (a) and (b) of the prolongations of the two input waveguides and two output waveguides are shifted overlapping by 24mum. Consequently, crosstalk is reduced even in the crossing type optical waveguide whose angle of intersection is small, the loss is reduced, and the length of the intersection part is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to optical devices used in optical communication and optical information processing, and particularly to a crossed optical waveguide with low crosstalk.

[Conventional technology]

The conventional cross-over optical waveguide was introduced in 1986, Proceedings of the General National Conference of the 4-child Communication Society, p. 4-191 (1988).
As described in , the meandering of the optical path at the intersection of straight optical waveguides results in a refractive index profile within the optical waveguide.

Or 1981 IEICE General National Conference Proceedings 8
13-13, p. 4-241 (1982), a plurality of electrodes were attached to the intersection to control the refractive index distribution at the intersection to reduce crosstalk.

[Problem that the invention seeks to solve]

The above conventional technology does not take into account changes in the optical path due to an increase in the width of the optical waveguide at the intersection in optical waveguides with a shallow crossing angle, that is, the bending of the optical path. Due to the considerations taken onboard the ship, the coupling was misaligned, resulting in crosstalk.

The present invention aims to suppress crosstalk by taking into consideration the bending of the optical path due to the increase in the width of the optical waveguide at the intersection of the optical waveguide.

[Means for solving problems]

The above purpose is to arrange the output side optical waveguides so that the coupling is better when the intersection of the center lines of the output side optical waveguides is closer to the input end than the intersection of the center lines of the input side optical waveguides at the intersection of the optical waveguides. This is achieved by arranging wave channels.

[Effect]

In a crossed optical waveguide, the light from the input optical waveguide overlaps with the other input optical waveguide at the intersection, which increases the width of the optical waveguide. The input light wave path will be bent to the side. For this reason, the center line of the output side optical waveguide is shifted from the center line of the input side optical waveguide in the direction in which the optical path is curved, and the optical waveguide is placed on this optical path.

This makes it possible to increase the coupling efficiency to one output-side optical waveguide and at the same time reduce the coupling to the other, thereby lowering crosstalk. In addition, the length of the intersection of the optical waveguides is short, and miniaturization can be achieved at the same time. This effect becomes larger as the intersection angle becomes smaller.

〔Example〕

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

Crossing angle θ is 5 in a crossed optical waveguide with 2 manual power and 2 outputs.
(in degrees), the width of the optical waveguide is ~2 μm. Clad 3
The refractive index of is 3.15. The refractive index of the optical waveguide is 3.3. On one side 1-1 of the input optical waveguide of this crossed optical waveguide,
Light with a wavelength of ~1.3 μm and a beam diameter of ~2 μm is incident. When the output side optical waveguide is arranged on the extension line of the input optical waveguide as in the conventional case, two leading waveguides (2-1, 2-
The power ratio of the light emitted from 2) is almost equal, and the crosstalk is 2-1 output P1 to 2-2 output P2.
It was defined as the ratio when . On the other hand, the arrangement was shifted so that the intersection points (alb) of the respective extension lines of the two input optical waveguides and the output optical waveguide overlapped by 24 μm, and a crosstalk of 125 dB or less was obtained.

〔Effect of the invention〕

According to the present invention, by shifting the center lines of the optical waveguides and intersecting them, it is possible to lower crosstalk, reduce loss, and shorten the length of the intersection even in a crossed optical waveguide with a small crossing angle. , curved optical waveguides and the like for enlarging the crossing angle to reduce crosstalk can be omitted. The structure of the optical integrated circuit can be made simple and compact.

[Brief explanation of the drawing]

FIG. 1 is a schematic layout diagram of an embodiment of the present invention. 1-1.2... Input optical waveguide, 2-1.2... Output optical waveguide, 3... Clad area, θ... Intersection angle, a
... Intersection of the center lines of the input-side leading waveguide, b... Intersection of the output-side optical waveguide.

Claims (1)

[Claims] 1. In a crossed optical waveguide where two optical waveguides intersect, the intersection of the extension lines of the center lines of each of the two input optical waveguides and 2
An optical waveguide characterized in that the intersection of the extension lines of the center lines of each of the two output optical waveguides is shifted so that two vertices formed by the center lines overlap.