JPS61121042A - Optical switch - Google Patents

Abstract

PURPOSE:To make a device including coupling parts small-sized by arranging optical waveguides for incident light in parallel approximately on a substrate and providing another output-side optical waveguide of a multiplexer crossing said optical waveguides and providing an optical switch of total reflection type at each intersection of optical waveguides. CONSTITUTION:Optical waveguides of load type coated with a tantalum oxide are used as the first - the fourth optical waveguides 2-5. Input-side and output-side end faces 16 and 17 of a substrate 1 are produced by cleavage along the R surface of a sapphire. The first - the fifth optical waveguides 2-6 are produced in parallel and vertically to the input end face in accordance with the core diameter of an optical fiber. Another optical waveguide, namely, the fifth optical waveguide 6 is provided to cross the first - the fourth optical waveguides 2-5 at 2 deg. and is bent at a low curvature before the output end face 17 to be vertical to the output end face. The thickness of an aluminum oxide of the waveguide is increased twice in crossing parts, and 1A-4A optical switches 8-11 are provided there.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical switch used for transmitting optical signals, and particularly to an optical switch that is particularly effective when having a plurality of transmission paths.

2. Description of the Related Art Optical switches used in optical signal transmission systems are used to switch transmission paths and selectively extract and send out optical signals. Conventionally, optical switches have been used to change the optical path by mechanically driving a prism or mirror, but because they are mechanical, the response speed is slow, and recently electronic optical switches that use electro-optic or acousto-optic effects have been used. has begun to be studied. Among these, total internal reflection type optical switches are ultra-high speed and ultra-compact.
The most practical. (C.S., Tsai, IEICK
J.

Quantum, Electronics & People pp
lications, vol.

QE-14PI) 513.1978) Problems to be Solved by the Invention When configuring an optical multiplexer using conventional total reflection type optical switches, it is difficult to combine two optical waveguides on the input side with one total reflection type optical switch. A control electrode is placed at the intersection of the waveguides, and the electro-optic effect changes the isolateral refractive index at the intersection to cause the guided light to be transmitted or totally reflected, thereby switching the optical path. In this case, if one of the output sides is used as an output waveguide, by controlling the electric field at the intersection, it is possible to select the optical signal on the total reflection side when an electric field is applied, and the optical signal on the straight transmission side when no electric field is applied. An optical multiplexer is constructed by connecting such total reflection type optical switches in a multi-stage pyramid shape.

In other words, if N stages are connected, it becomes a multiplexer with two input ports. Of course, if the input and output are reversed, it becomes a demultiplexer.

In the conventional configuration, the optical waveguides intersect at an angle, so when the optical waveguides are multistage, the difference in angle between the many optical waveguides becomes large at the input end, making coupling to an external optical fiber etc. extremely difficult. Conventionally, a part of the substrate had a gentle curvature and the optical waveguides were arranged in parallel, but since the curvature could not be made large, the overall size of the substrate became large. In addition, the angle of the optical switch part on the crystal axis of the substrate differs depending on the switch, and the electro-optic effect varies depending on the switch, so the efficiency of the optical switch also changes, causing the problem that the applied voltage for control differs. Ta. In addition, the loss in an optical switch differs depending on the transmitted guided light and the totally reflected guided light, so when connecting multiple stages, the difference in intensity between the light transmitted through all stages and the light transmitted through all stages can be ignored. The problem was that I couldn't do it. Furthermore, due to the structure, it is difficult to configure the number of input ports other than 2N, and the drive circuit is also extremely complicated.

Means for Solving the Problems In order to solve the conventional problems, the present invention first arranges optical waveguides for incident light almost parallel on a substrate, and then connects the output side of another multiplexer that intersects these optical waveguides. An optical waveguide is provided. A total reflection type optical switch is provided at the intersection of each optical waveguide.

Operation The optical switch according to the present invention operates by applying an electric field only to the optical switch disposed in the optical waveguide of the desired channel to be detected.

By sequentially applying an electric field to each optical switch, it operates as an optical multiplexer that sequentially detects a large number of incident optical signals.

Of course, if reversed, it also works as a demultiplexer.

In the present invention, in a total reflection type optical switch, when no electric field is applied, that is, there is almost no loss in the transmitted guided light, but the guided light that is totally reflected has a loss of about 1 decibel at the switch part. In this case, since the incident light of any channel is totally reflected only - times, the optical signal loss due to the channels has little variation and is almost constant.

Further, the number of incident optical signals is arbitrary and is not limited to 2, and the application of an electric field can be easily implemented using a circuit such as a shift register.

Furthermore, since the waveguides to which each incident light beam is connected can also be constructed in parallel, there is an effect that the light beams can be collectively coupled to an optical fiber array using a prism, a lens, or the like. Therefore, it can be made extremely compact including the coupling portion. Furthermore, since the optical switches are arranged in parallel, the electro-optic effect is the same and the drive circuit can be the same, which is convenient.

Example FIG. 1 is a schematic diagram showing an embodiment of the present invention.

For the substrate 1, a PLZT thin film, which is a material that has a large electro-optic effect and is free from optical damage, was epitaxially grown on a sapphire C surface. The first to fourth optical waveguides were so-called road-type optical waveguides in which a thin layer of aluminum oxide was provided in a band shape and the entire structure was covered with mental oxide. The input side and output side end faces 16 and 17 of the substrate 1 are made of sapphire.
As a result of cleavage according to the plane, the cleaved plane is extremely smooth and almost perpendicular to the multiple optical waveguides.
It was suitable for end face bonding. The first to fifth optical waveguides 2 to 6 were fabricated parallel to each other at a pitch of 126 microns to match the core diameter of the optical fiber and perpendicular to the input end surface. Another optical waveguide intersects these optical waveguides, that is, the sixth optical waveguide.
The optical waveguide 6 was provided at an intersecting angle of 2 degrees with the first to fourth optical waveguides 2 to 5, and was bent with a gentle curvature before the output end face 17 so as to be perpendicular to the output end face. The thickness of the aluminum oxide of the waveguide is 2 at the intersection of each optical waveguide.
There are 1 person light switch 8 to 4 person light switch 11.
has been established. When no electric field is applied between the electrodes of these optical switches, the guided light in the first to fourth optical waveguides travels straight,
It does not move to the sixth optical waveguide 6. Here, since the thickness of the aluminum oxide at the intersection is thick, there is little light leakage.

Here, when an electric field is applied to any optical switch, the guided light traveling through that optical waveguide transfers to the sixth optical waveguide 6. Therefore, by sequentially operating one to four optical switches, it was possible to operate it as a four-person multiplexer. In this embodiment, a sixth optical waveguide 7, which is another optical waveguide, is provided on the same substrate 1, and a function of demultiplexing one input to a plurality of optical waveguides is also incorporated. Since the operation of the optical switch section is the same, the explanation will be omitted, but it can also be used as an accessor for the optical transmission line. That is, for example, if an attempt is made to access an optical signal propagating through the second optical waveguide 3, an electric field is applied to the two-person optical switch 9, and the optical signal can be extracted as an output signal from the fifth optical waveguide 6. This signal can be returned to the second optical waveguide as it is or after data processing from the sixth optical waveguide 7 to the 2B optical switch 13, thereby functioning as an accessor. In this case, it is convenient for the optical signals in the other waveguides to propagate and pass through the accessor part. Of course, it is also possible to switch the optical signal from any optical waveguide to any optical waveguide by simple signal processing.

Effects of the Invention As described in the embodiments above, the present invention includes a multiplexer,
It has a wide range of uses, including demultiplexers, accessors, and exchanges, and is extremely effective in transmitting optical signals, making it highly effective in industrial applications.

[Brief explanation of the drawing]

The figure is a schematic plan view of an optical switch according to an embodiment of the present invention. 1... Substrate, 2-7... Optical waveguide, 8
~15... Optical switch, 16.17...
・Output end face.

Claims (4)

[Claims] (1) A total internal reflection type optical switch is constructed by arranging multiple optical waveguides arranged almost in parallel on a substrate and another optical waveguide that intersects these optical waveguides, and forming a total internal reflection type optical switch at the intersection of each optical waveguide. and an optical switch that detects or transmits an optical signal from any one of the plurality of optical waveguides by controlling a group of these total reflection type optical switches. (2) Another optical waveguide is arranged so as to intersect with the plurality of optical waveguides, and a total internal reflection type optical switch is constructed at the intersection of each optical waveguide. 2. The optical switch according to claim 1, wherein the optical switch is configured to be capable of detecting or transmitting an optical signal from any one of the plurality of optical waveguides by controlling the optical waveguide. (3) The optical switch according to claim 2, wherein the optical signal detected through one switch group is transmitted directly or after signal processing through the other switch group. (4) The optical switch according to claim 1, wherein the end face of the substrate is formed substantially perpendicular to the plurality of optical waveguides.