JPH01133026A - Optical parts - Google Patents

Abstract

PURPOSE:To reduce the size of optical parts by forming at least one layer of spiral thin films which are coated with insulating layers and consist of a superconducting material on the side faces of a magneto-optical crystal and generating a magneto-optical effect by the magnetic field generated when electric current is passed to the thin films. CONSTITUTION:The superconducting layer 202 is formed on the side faces of the yttrium-garnet (YIG) crystal 201. The layer 202 is worked to a spiral shape. The insulating layer 203 consisting of SiO2 and the superconducting layer 204 consisting of the same material as the material of the layer 202 are then successively formed thereon. However, the end part of the insulating layer 203 is partially removed in order to conduct the superconducting layers 202, 204. The superconducting layer 204 is then worked to a spiral shape and finally, the insulating layer 206 is formed. Polarizers 102, 103 are disposed to the YIG crystal 101 formed with the superconducting coils along the optical axis thereof so that light can pass the same only from the left to the right. Since the need for using a permanent magnet is thereby eliminated, the size of the optical parts is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to optical components using magneto-optic crystals, such as optical isolators, used in optical communication, optical measurement, and the like.

2. Description of the Related Art In recent technologies such as optical communication and optical measurement, optical components such as optical demultiplexers and wavelength filters are indispensable. Among these, devices using magneto-optic crystals, such as optical isolators and magnetic field sensors, are extremely important because they have the unique function of rotating the plane of polarization in the same direction as the direction of travel, regardless of the direction of light incidence. be. An example of a conventional optical isolator is shown in FIG.
7 years) is shown. In the figure, 1 is a garnet crystal (hereinafter referred to as YIG crystal) made of yttrium and iron oxides, and due to the application of a magnetic field by a permanent magnet 2, an optical anisotropy called the Faraday effect occurs. The plane of polarization of light rotates. This rotation angle depends on the strength of the magnetic field and YI
It is determined by the optical path length of the G connection and high school, and is currently set to rotate by 45 degrees. At this time, the light with the plane of polarization selected by the polarizer 6 enters another polarizer 7, but by adjusting the angle of this polarizer 7, the loss in intensity of the output light 110 relative to the input light 10 is approximately 1 It can be suppressed to about 2 to 2 decibels. On the other hand, when the above settings are made and the incident light 12 is made to enter from the opposite direction, the light having the polarization component selected by the polarizer T will have a polarization direction that allows it to pass through the polarizer 5 when passing through the YIG crystal. The plane of polarization is rotated so that it is perpendicular to Therefore, the light intensity of the emitted light 13 is very small, and the loss is about 30 decibels compared to that of the incident light 12. The above is the operating principle of the optical isolator.

Problems to be Solved by the Invention However, according to the above configuration, in order to generate a magnetic field of sufficient strength, a permanent magnet with a volume several to ten times as large as that of a YIG crystal is required, and the optical isolator is It was preventing miniaturization. This problem is not limited to optical isolators, but applies to all optical components using magneto-optic crystals.

Means for Solving the Problems In order to solve the problems, the present invention provides a configuration in which light is incident along the center line of a cylindrical or prismatic magneto-optic crystal, and an insulating layer is provided on the side surface of the magneto-optic crystal. covered,
The present invention also provides an optical component characterized in that at least one spiral thin film made of a superconducting material is formed, and a magneto-optic effect is caused by a magnetic field generated by shunting current through the thin film.

Effect: According to the above-mentioned configuration, the size of the optical component can be reduced because no permanent magnet is required. Furthermore, since a superconducting material is used, if a current is generated at the time of shipment, the current will continue to flow permanently after that, so there is no need for a permanent power source.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention, taking an optical isolator as an example. Reference numeral 101 is a YIG crystal on which a spiral thin film (hereinafter referred to as a superconducting coil) made of a superconducting substance is formed on the side surface.

A polarizer 10 is installed so that light passes through this YIG crystal only from left to right along the optical axis indicated by the dotted chain line in the figure.
2, 103 are arranged. YIG with superconducting coil
A method for manufacturing the crystal 101 will be explained using the cross-sectional view of FIG. First, as shown in the figure, a superconducting layer 202 is formed on the side surface of a YIG crystal 201 by sputtering or the like. The superconducting material used is, for example, strontium-doped Y+ Ba,
Cu50. −δ. This layer 201 is processed into a spiral shape using a precision lathe as shown in FIG. The dashed line indicates the shape of the spiral. Next, an insulating layer 203 consisting of 5in2
and a superconducting layer 204 made of the same material as 202 are sequentially formed by sputtering. However, superconducting layer 202.2
In order to make the insulating layer 203 conductive, the end portion of the insulating layer 203 is partially removed as shown in FIG. Next, the superconducting layer 204 is processed into a spiral shape using a precision lathe, and finally the insulating layer 204 is processed into a spiral shape.
Form 06. The dashed line shows this spiral state (d).

The superconducting coil created in this way has an electrically closed loop. Therefore, if a wire is broken at one point, a power supply is connected, a direct current is applied, and the broken wire is repaired using a superconducting material, the current continues to flow through the coil, and a steady magnetic field 205 is applied to the YIG crystal. The rotation angle of the polarization plane is determined by the length of the YIG crystal, the amount of current flowing through the coil, and the number of turns of the coil.

In this example, the superconducting coil has a two-layer structure, but one
There is no problem with a layer or three or more layers. Furthermore, although this embodiment takes an optical isolator as an example, the present invention is not limited to optical isolators.

Effects of the Invention According to the present invention, since permanent magnets are not required, the number of parts can be reduced and the assembly process can be simplified.

Furthermore, since a superconducting material is used for the coil, a large current can be passed through it, and a strong magnetic field can be generated.

Furthermore, the magnetic field can be easily strengthened by increasing the number of turns of the coil.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an electronic component according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the manufacturing process of the YIG crystal with superconducting coil in FIG. 1, and FIG. 3 is a conventional electronic component. FIG. 101...YIG crystal with superconducting coil, 102゜1
03...Polarizer, 104,105...YI
(, crystal holder, 106.107... polarizer holder, 108... holder.

Claims (1)

[Claims] A magnetic field comprising at least one spiral first thin film made of a superconducting material and at least one second thin film made of an insulator covering the surface of the first thin film on a main surface through which light does not pass. An optical component including an optical crystal, wherein the direction of a magnetic field generated when a current is passed through the first thin film is parallel to the direction of propagation of light passing through the magneto-optic crystal.