JPH1010587A - Magneto-optical effect optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical effect optical switch of a two inputs two outputs type capable of realizing low cross talk of -30dB or below with simple and inexpensive constitution. SOLUTION: This optical switch is provided with two magneto-optical effect optical switch parts 101, 102 of a one input two outputs structure provided with a first polarization beam splitter 1 splitting incident light P1 (P2) to transmission light Q1 and reflection light Q2, a second polarization beam splitter 2 superposing the transmission light Q1 and the reflection light Q2 and emitting it, Faraday rotators 11, 12 respectively provided in the optical paths of the transmission light Q1 and the reflection light Q2 and a third polarizing beam splitter 3 provided to separate and eliminate a P polarization component incorporated in the reflection light Q2. and selectively emitting the light from two output parts 2a, 2b of the second polarizing beam splitter 2 by changing the Faraday rotational angles of the Faraday rotators 11, 12, two half mirrors 201, 202 and optical fiber transmission lines 301-304 connecting them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-mechanical optical switch used for switching an optical signal in an optical communication transmission system, and more particularly to a two-input two-input type two-input type two-output type optical switch. The present invention relates to an output type magneto-optical effect optical switch.

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a conventional relatively inexpensive two-input two-output type magneto-optical effect optical switch. This magneto-optical effect optical switch includes two polarization beam splitters 51 and 52 and two Faraday rotation elements 61 and 62.
And two reflecting prisms 71 and 72. Incident lights P1 and P2 are incident on the first polarizing beam splitter 51 from two directions orthogonal to each other. Most of the P-polarized light component in the first incident light P1 passes through the first polarization beam splitter 51 and is incident on the first Faraday rotation element 61, where the polarization plane is rotated, and then the second The light enters the polarization beam splitter 52. On the other hand, the first incident light P1
Most of the S-polarized light components therein are reflected by the first polarizing beam splitter 51, enter the second Faraday rotator 62 through the first reflecting prism 71, and rotate the polarization plane here. The light enters the second polarization beam splitter 52 via the second reflection prism 72.

Similarly, most of the S-polarized light component of the second incident light P2 is reflected by the first polarization beam splitter 51 and enters the first Faraday rotation element 61, where the polarization plane is rotated. After that, the second polarization beam splitter 52
Incident on. On the other hand, most of the P-polarized light component of the second incident light P2 passes through the first polarization beam splitter 51, passes through the first reflection prism 71, and passes through the second Faraday rotation element 62.
After the polarization plane is rotated here, the light enters the second polarization beam splitter 52 via the second reflection prism 72. First and second Faraday rotation elements 61, 62
Is set such that when the magnetic fields M1 and M2 are applied up to the saturation magnetic field strength, the polarization plane rotation angle of the outgoing light with respect to the incident light becomes 90 degrees. In this magneto-optical effect optical switch, the first and second Faraday rotators 6
When the intensity of the magnetic fields M1 and M2 applied to the first and second magnetic fields M1 and M2 is 0, most of the first incident light P1 is output as the outgoing light P3 in the same direction as the first direction. It is output as outgoing light P4 orthogonal to P1. Similarly, the second incident light P2 has a magnetic field M
When the intensities of M1 and M2 are 0, most are output as the outgoing light P4, and when the intensities of the magnetic fields M1 and M2 are the saturation intensity, most of them are output as the outgoing light P3.

[0004]

However, in the above-mentioned conventional magneto-optical effect optical switch, the reflected light from the first polarizing beam splitter 51 is reduced from 1% to 0.1%.
% Of P-polarized light components, it is extremely difficult to realize low crosstalk of -30 dB or less. An object of the present invention is to provide a simple and inexpensive configuration with -30 dB.
An object of the present invention is to provide a two-input two-output type magneto-optical effect optical switch capable of realizing the following low crosstalk.

[0005]

In order to solve the above-mentioned problems, a magneto-optical effect optical switch according to the present invention separates incident light into transmitted light (P-polarized component) and reflected light (S-polarized component). A first polarization beam splitter, a second polarization beam splitter that superimposes and transmits transmitted light and reflected light from the first polarization beam splitter, and a second polarization beam splitter from the first polarization beam splitter. A Faraday rotator provided on the optical path of the transmitted light and the reflected light, and a Faraday rotator provided on the optical path of the reflected light from the first polarizing beam splitter to separate and remove the P-polarized component contained in the reflected light. A third polarization beam splitter, and changing the Faraday rotation angle of the Faraday rotation element to switch the light emission direction from the second polarization beam splitter. Provided with more two two magneto-optical effect optical switching unit of one input and two outputs structure without to output a selectively emit light from the output section, and two optical output,
The light emitted from the first output unit of the one magneto-optical effect optical switch unit and the light emitted from the second output unit of the other magneto-optical effect optical switch unit are emitted from the one optical output unit, and The light emitted from the second output portion of the magneto-optical effect optical switch portion and the light emitted from the first output portion of the other magneto-optical effect optical switch portion are emitted from the other optical output portion. It is characterized by having done. In the magneto-optical effect optical switch of the present invention configured as described above, a third polarization beam splitter is provided on the optical path of the reflected light from the first polarization beam splitter constituting each magneto-optical effect optical switch unit,
Since the light of the P polarization component included in the reflected light from the first polarization beam splitter is separated and removed, low crosstalk of −30 dB or less can be sufficiently achieved in each magneto-optical effect optical switch unit. With this optical switch as a whole, low crosstalk of -30 dB or less can be achieved.

[0006]

Embodiments of the present invention will be described below. FIG. 1A is a schematic configuration diagram showing an example of an embodiment of a magneto-optical effect optical switch according to the present invention. This magneto-optical effect optical switch includes two magneto-optical effect optical switches 101 and 102 having a one-input two-output structure,
Two half mirrors 201 and 202 and 4 connecting them
The optical fiber transmission lines 301 to 304 are provided. Each of the magneto-optic effect optical switch units 101 and 102 has one input unit 401 and two output units 501 and 502, respectively. Each of the half mirrors 201 and 202 includes a first light input unit 201a and 202a, a second light input unit 201b and 202b, and a light output unit 201c and 202, respectively.
c. Then, one half mirror 201
The first optical input unit 201a has a first optical switch 10
One first output unit 501 is connected to the second optical input unit 201b, and the second output unit 502 of the second optical switch 102 is connected via optical fiber transmission lines 301 and 303, respectively. The first output section 501 of the second optical switch 102 is connected to the first optical input section 202a of the half mirror 202, and the second output section 501 of the first optical switch 101 is connected to the second optical input section 202b. The output unit 502 is connected via the optical fiber transmission lines 302 and 304, respectively.

FIG. 1B is a schematic configuration diagram showing an example of an embodiment of the first and second magneto-optical effect optical switch units 101 and 102. As shown in FIG. The first and second magneto-optical effect optical switches 101 and 102 each include three polarization beam splitters 1, 2, and 3; two Faraday rotators 11 and 12; and two reflection prisms 21 and 22. . The first polarizing beam splitter 1 includes an incident light P1,
Most of the P-polarized component in P2 is transmitted as it is, and the S-polarized component is reflected. The transmitted light Q1 transmitted through the first polarization beam splitter 1 is incident on the first Faraday rotation element 11, where it is incident on the second polarization beam splitter 2 while being rotated in the polarization direction. On the other hand, the reflected light Q2 from the first polarizing beam splitter 1 enters the third polarizing beam splitter 3, where the P-polarized light component included in the reflected light Q2 is separated and removed, and then the first reflecting prism The light is incident on the second Faraday rotator 12 via 21, and is incident on the second polarization beam splitter 2 via the second reflecting prism 22 while being rotated in the polarization direction. The second polarization beam splitter 2 emits light from the first emission part 2a or the second emission part 2b depending on the angle of the plane of polarization of the incident light.

[0008] First and second Faraday rotation elements 11,
Reference numeral 12 denotes a case where a magneto-optical material is provided inside an electromagnetic coil. When the magnetic fields M1 and M2 are applied to the magneto-optical material up to the saturation magnetic field strength by the electromagnetic coil, the polarization plane rotation angle of the outgoing light with respect to the incident light becomes 90 degrees. It is set to be a degree. When the intensity of the magnetic fields M1 and M2 applied to the first and second Faraday rotation elements 11 and 12, respectively, is zero, the first and second magneto-optical effect optical switch units 101 and 102 respectively output the incident light P1 and P2. Is output from the first output unit 2a of the second polarization beam splitter 2 as the outgoing light R1 in the same direction as the incident lights P1 and P2, and when the magnetic fields M1 and M2 have the saturation intensity, the second polarization The incident light P1, from the second output unit 2b of the beam splitter 2,
It is set so as to be output as emission light R2 in a direction orthogonal to P2.

In the magneto-optical effect optical switch of the present embodiment configured as described above, the magnetic field applied to the Faraday rotator elements 11 and 12 inside the first and second magneto-optical effect optical switch units 101 and 102. When the intensities are all 0, the first incident light P1 is output from the first output unit 501 of the first optical switch 101, and then output as the output light P3 via the optical fiber transmission path 301 and the half mirror 201. , The second incident light P2 is the first incident light of the second optical switch 102.
Output from the output unit 501 of the optical fiber transmission line 3
The light is output as output light P <b> 4 via the light source 04 and the half mirror 202. Conversely, when a magnetic field having a saturation magnetic field strength is applied to the Faraday rotation elements 11 and 12, the first incident light P1
Is output from the second output section 502 of the first optical switch 101, is output as output light P4 via the optical fiber transmission path 302 and the half mirror 202, and the second incident light P2 is output from the second optical switch 101. After being output from the second output unit 501 of 102, the light is output as output light P <b> 3 via the optical fiber transmission path 303 and the half mirror 201.

In the magneto-optical effect optical switch, the third polarization beam splitter 3 is provided between the first polarization beam splitter 1 and the first reflection prism 21 constituting each of the magneto-optical effect optical switches 101 and 102. Provided in the reflected light Q2 from the first polarizing beam splitter 1.
Since the light of the polarized light component (1% to 0.1% of the reflected light P3) is separated and removed by the third polarizing beam splitter 3, only the S-polarized light components of the incident lights P1 and P2 are converted to the first light. The light can be guided to the second polarization beam splitter 2 via the reflection prism 21, the Faraday rotation element 12, and the second reflection prism 22. Further, regarding the S-polarized light component mixed in the transmitted light Q1 from the first polarization beam splitter 1, the polarization filter 4 and the like are disposed between the first polarization beam splitter 1 and the first Faraday rotation element 11. Can be easily removed and a crosstalk of -50 dB or less can be realized. Therefore, low crosstalk of −30 dB or less can be sufficiently achieved in each of the optical switch units 101 and 102, and the optical switch as a whole can also achieve −
Low crosstalk of 30 dB or less can be sufficiently achieved. The installation position of the third polarizing beam splitter 3 is the first position.
Anywhere on the optical path between the polarization beam splitter 1 and the second Faraday rotator 12, for example,
First reflection prism 21 and second Faraday rotation element 1
A third polarizing beam splitter 3 may be provided between the second polarizing beam splitter 3 and the second polarizing beam splitter 3.

[0011]

As described above, according to the present invention,
One input in which a polarizing beam splitter is provided on the optical path of the reflected light from the first polarizing beam splitter to prevent the P-polarized component from being mixed into the S-polarized component which causes crosstalk deterioration of the optical switch. By using a combination of two magneto-optical effect optical switches having a two-output structure, it is possible to provide a low-crosstalk, two-input, two-output magneto-optical effect optical switch of -30 dB or less with a simple and inexpensive configuration. it can.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram illustrating an example of an embodiment of a magneto-optical effect optical switch according to the present invention, and FIG. 1B is a diagram of a magneto-optical effect optical switch unit that is a component of the magneto-optical effect optical switch. 1 is a schematic configuration diagram illustrating an example of an embodiment.

FIG. 2 is a schematic configuration diagram illustrating an example of a conventional magneto-optical effect optical switch.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 first polarizing beam splitter, 2 second polarizing beam splitter, 3 third polarizing beam splitter, 11
1st Faraday rotation element, 12 2nd Faraday rotation element, 21 1st reflection prism, 22 2nd reflection prism, 101, 102 Magneto-optical effect optical switch part, 201, 202 Half mirror, 301-304
Optical fiber transmission line, 501 first output section, 502 second output section, 201a, 202a first optical input section, 2
01b, 202b Second light input unit, 201c, 202
c Light output unit.

Claims (1)

[Claims] 1. A first polarization beam splitter for separating incident light into transmitted light and reflected light, and a second polarized beam emitted by superimposing transmitted light and reflected light from the first polarized beam splitter. A splitter; a Faraday rotator provided on an optical path of transmitted light and a reflected light from the first polarizing beam splitter to the second polarizing beam splitter; and an optical path of the reflected light from the first polarizing beam splitter. A third polarizing beam splitter provided for separating and removing a P-polarized component included in the reflected light, and changing the Faraday rotation angle of the Faraday rotation element to change the light from the second polarizing beam splitter. Two magneto-optical effect optical switch units having a one-input two-output structure in which the output directions are switched to selectively output the output light from the two output units. And two light output sections, one of which outputs light emitted from a first output section of one magneto-optical effect optical switch section and light emitted from a second output section of the other magneto-optical effect optical switch section. And the light emitted from the second output part of the one magneto-optical effect optical switch and the light emitted from the first output part of the other magneto-optical effect optical switch A magneto-optical effect light switch, wherein the light is emitted from the light output section.