JPH0380287B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to improving the loss of a 1×N high-speed optical switch that utilizes the electro-optic effect.

<Prior art> The optical switch that has been reported so far for switching each sensor in an optical fiber sensor system is a 1×6 optical switch that mechanically moves a mirror.
There are optical switches and N×N matrix switches.
There are also N×N matrix switches for switching image signals using electro-optic crystals or liquid crystals.

<<Problems to be Solved by the Invention>> However, the principle of mechanically moving the mirror is poor in reliability for sensor signal switching. Further, since the matrix switch for image signal switching uses a 1×N branching element and an N×1 merging element, the theoretical loss (1/N in one way) is large and the configuration is complicated.

The present invention has been made to solve the above problems, and its object is to realize a 1×N high-speed optical switch that has low loss, has no moving parts, is highly reliable, and has a simple configuration.

<Means for Solving the Problems> The optical switch according to the present invention includes a first polarizing beam splitter that separates input light, and a first polarizing beam splitter that is arranged in series on the same straight line. a plurality of second polarizing beam splitters into which one end of the polarized light is inputted; a first total reflection prism into which the other polarized light outputted from the first polarized beam splitter is input; A plurality of third polarizing beam splitters arranged in series on the same straight line input the output of the first total reflection prism into one end thereof, and output the output from the other end of the plurality of third polarizing beam splitters. a second total reflection prism that inputs light and outputs the light to the other end of the plurality of second polarization beam splitters; an electro-optical element disposed between the third polarizing beam splitters of the second total reflection prism and the plurality of third polarizing beam splitters and the plurality of second polarizing beam splitters. a half-wave plate arranged;
The present invention is characterized in that the combination of the first and second polarizing beam splitters through which light is input and output is switched by driving a predetermined electro-optical element.

The optical switch according to the second aspect of the present invention includes a first polarized beam splitter that separates input light, and one polarized light that is arranged in series on the same straight line and outputted from the first polarized beam splitter. a plurality of second polarizing beam splitters that input the polarized light to one end thereof, and a first total reflection prism that inputs the other polarized light output from the first polarized beam splitter, arranged in series on the same straight line. A plurality of third polarizing beam splitters input the output of the first total reflection prism to one end thereof, and a plurality of third polarizing beam splitters inputting the light output from the other end of the plurality of third polarizing beam splitters to one end thereof. a second total reflection prism outputting to the other end of the second polarizing beam splitter;
and an electro-optical element disposed between the plurality of second polarizing beam splitters and between the total reflection prism and the plurality of third polarization beam splitters, and the total reflection prism and the plurality of third polarization beam splitters. The first and second polarizing beam splitters include a half-wave plate disposed between a plurality of polarizing beam splitters and a plurality of polarizing beam splitters, and light is input/output by driving a predetermined electro-optic element. It is characterized in that the combination of polarizing beam splitters can be switched.

<<Operation>> According to the configuration according to the present invention, the input light is polarized and separated, and then the two linearly polarized lights are combined again and output. Therefore, by driving a predetermined electro-optical element, any combination Light can be input and output from the two polarizing beam splitters with low loss.

"Example" The present invention will be explained in detail below using the drawings.

FIG. 1 is a configuration explanatory diagram showing one embodiment of an optical switch according to the present invention. 1 to 6 are optical fibers, 7
- 12 are rod lenses for focusing light coupled to the optical fibers 1 - 6, respectively; 13 - 17 are polarizing beam splitters arranged in series on a straight line and connected to the rod lenses 7 - 12, respectively; and 21 are polarizing beam splitters. a total reflection prism that reflects the linearly polarized light from the splitter 13; polarized beam splitters 18 to 20 arranged in series on a straight line corresponding to the polarized beam splitters 14 to 16, respectively;
22 reflects the light that has passed through the polarizing beam splitters 18 to 20 and returns it to the polarizing beam splitter 1.
A total reflection prism 7 is added, 23 to 26 are electro-optical elements provided between the polarization beam splitters 13 to 17, and 27 to 30 are total reflection prisms 21 and 22 and polarization beam splitters 18 to 2.
PLZT is used here as an electro-optical element provided between 0 and 0. Electro-optical elements 23-3
0 is provided with signal lines and electrodes for applying control signals (not shown in the figure). 31 to 35 are polarizing beam splitters 18 to 20 and half-wave plates (which rotate the polarization plane of light by 90 degrees) installed between the total reflection prisms 22 and 21 and the polarizing beam splitters 14 to 17 and 13, respectively. polarizer). 1
31 to 201 are beam splitter surfaces (BS surfaces) of the polarizing beam splitters 13 to 20, respectively. Polarizing beam splitters 14 and 17 correspond to one end and the other end of the plurality of second polarizing beam splitters, respectively, and polarizing beam splitters 18 and 20 correspond to one end and the other end of the plurality of third polarizing beam splitters, respectively. It corresponds to

The operation of the optical switch having such a configuration will be explained next. Since the light incident from the fiber 1 through the rod lens 7 is non-polarized light, the planes of polarization make an angle of 90° to each other due to the beam splitter surface (BS surface) 131 of the polarized beam splitter 13 (first polarized beam splitter). It is separated into two linearly polarized S waves and P waves. The P wave (parallel to the paper) passes through the BS plane 131 and proceeds in the X direction of the figure, and the S wave (perpendicular to the paper)
It is reflected by the BS surface 131 and travels in the Y direction in the figure. B.S.
The P wave transmitted through the surface 131 passes through the electro-optical elements 23 to 2.
If no control signal is added to 6, BS planes 141 to 1
71 and is output to the optical fiber 6 via the rod lens 12. S reflected by BS surface 131
When the wave passes through the half-wave plate 35, the plane of polarization is rotated by 90 degrees and becomes a P wave. The P wave reflected by the total reflection prism 21 passes through the BS surfaces 181 to 201 unless a control signal is applied to the electro-optical elements 27 to 30.
After being reflected by the total reflection prism 22, the polarization plane is rotated by 90° again by the half-wave plate 34 to become an S wave, which becomes a BS wave.
It is combined with the P wave reflected by the surface 171 and transmitted through the BS surface 171. Here, for example, a control signal (half wavelength voltage - polarization plane of light is changed to 90°) is sent to the electro-optical element 25.
When applying a rotating voltage), the BS surface 131,1
41, 151, the polarization plane is rotated by 90 degrees when passing through the electro-optical element 25 and becomes an S wave, so it is reflected by the BS surface 161 and output to the optical fiber 4 via the rod lens 10. be done. Furthermore, when a control signal is applied to the electro-optical element 29, the BS
When the P wave that has passed through the surfaces 181 and 191 passes through the electro-optical element 29, the plane of polarization is rotated by 90° and becomes S.
The wave is reflected by the BS plane 201, and the polarization plane is rotated by 90 degrees by the half-wave plate 33 to become a P wave, which is reflected by the BS plane 1.
Pass through 61. That is, if the electro-optical elements 25 and 29 are driven simultaneously, all the light input from the optical fiber 1 is output to the optical fiber 4.

Similarly, the electro-optical elements 23, 27, 2
When control signals are applied to 4 and 28, 26 and 30, they are output to optical fibers 2, 3 and 5 via rod lenses 8, 9 and 11, respectively. FIG. 2 summarizes the above operating modes in a list (the circles indicate electro-optical elements to be driven in accordance with the output optical fibers).

That is, according to the optical switch configured as described above, the light incident from the fiber 1 can be arbitrarily switched to any one of the optical fibers 2 to 6 by applying a control signal to any of the electro-optic elements 23 to 30. be able to. Conversely, the light incident from any of the optical fibers 2 to 6 can be switched to the fiber 1 as desired. As a result, a highly reliable 1×N optical switch without moving parts can be realized with a simple configuration.

Also, after polarization separation, both linearly polarized light (P wave and S wave
waves) are combined again to produce output light, so in principle there is almost no loss.

In the above embodiment, instead of the optical fiber 1 and the rod lens 7, an optical fiber 1' and a rod lens 7' can be provided at the position shown by the dotted line in FIG. 1 (however, the driving mode is slightly different).

Furthermore, by selecting the voltages applied to the electro-optical elements 23 to 30, it is possible to branch the input light from the optical fiber 1 to the optical fibers 2 to 6 at any ratio (control voltages with intermediate values can be used). (By adding this, you can obtain intermediate transmittance or reflectance.) Conversely, it is also possible to combine at any ratio.

FIG. 3 shows a second embodiment of the optical switch according to the present invention, and is an explanatory diagram showing the structure of the device shown in FIG. 1, with the half-wave plate 35 omitted. The operating principle is the same as in the first embodiment, except that the half-wave plate 35
Since this is omitted, the drive mode of the electro-optical element is different, as shown in FIG.

If the configuration is as shown in FIG. 3, the same effects as the first embodiment can be produced, and the configuration can be simplified.

FIG. 5 is an explanatory diagram of a configuration shown in a third embodiment of the present invention. This is the apparatus shown in FIG. 1, configured so that two optical paths are input and output from the first polarizing beam splitter 13 and the second polarizing beam splitters 14 to 17, respectively, and the optical fibers 1 to 6
Optical fibers 1a to 6a and optical fibers 1b to 6b are provided in place of the rod lenses 7 to 12, and optical fibers 7a to 12a and optical fibers 7b are provided in place of the rod lenses 7 to 12.
~12b are provided. By using the drive mode shown in FIG. 2, the optical paths can be switched two at a time.

A device having such a configuration can be applied to a transmission type fiber sensor as shown in FIG. In Figure 6,
The light output from the light source 41 is sent to the sensor unit 42 via the optical fiber 40a, and (reflected light, etc.) returns to the optical sensor 43 via the optical fiber 40b. To apply the apparatus shown in FIG. 5 to this, for example, the light source 41 and the optical fiber 1a are coupled, and the optical fiber 2
a and the optical fiber 40a, and the optical fiber 40
b to the optical fiber 2b, and then the optical fiber 1b to the optical sensor 43.

When an optical switch switches optical paths in both directions at the same time, as in the above application example, the loss usually increases as the losses in both directions are multiplied together, but the device shown in Figure 5 is particularly advantageous because the loss is extremely small. becomes.

Note that in each of the above embodiments, the number of branches N is 5, but it is not limited to this and can be any number of branches.

Furthermore, since the loss is the same in both directions, it can be operated reversibly.

Further, although PLZT is used as the electro-optical element, it is not limited to this, and for example, liquid crystal or the like may be used.

<<Effects of the Invention>> As described above, according to the present invention, it is possible to realize a 1×N high-speed optical switch with a simple configuration that has low loss in principle, has no moving parts, and has high reliability.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the optical switch according to the present invention, FIG. 2 is an explanatory diagram for explaining the operating mode of the device shown in FIG. 1, and FIG. FIG. 4 is an explanatory diagram for explaining the operating mode of the device shown in FIG. 3, and FIG. 5 is a diagram showing a third embodiment of the optical switch according to the present invention. FIG. 6 is an explanatory diagram for explaining an application example of the apparatus shown in FIG. 5. 13...first polarizing beam splitter, 14-
17... second polarizing beam splitter, 21...
First total reflection prism, 18-20...Third polarizing beam splitter, 22...Second total reflection prism, 23-30...Electro-optical element, 31-35
...Half-wave plate.

Claims (1)

[Claims] 1. A first polarizing beam splitter that separates input light, and one polarized light output from the first polarizing beam splitter that is arranged in series on the same straight line and is input to one end thereof. A plurality of second polarizing beam splitters and a first total reflection prism inputting the other polarized light output from the first polarizing beam splitter are arranged in series on the same straight line, and the first total reflection prism is arranged in series on the same straight line.
a plurality of third polarizing beam splitters which input the outputs of the total reflection prisms into one end thereof; between a second total reflection prism outputting to the other end of the beam splitter and the first and plurality of second polarization beam splitters, and between the total reflection prism and the plurality of third polarization beam splitters; an electro-optical element disposed, and a half-wave plate disposed between the second total reflection prism, the plurality of third polarizing beam splitters, and the plurality of second polarizing beam splitters, 1. An optical switch characterized in that the combination of first and second polarizing beam splitters through which light is input and output is switched by driving a predetermined electro-optical element. 2. The optical switch according to claim 1, wherein the beam splitter surfaces of the first polarizing beam splitter and the second and third polarizing beam splitters are arranged at right angles to each other. 3. The optical switch according to claim 1, wherein the optical switch is configured to input and output two optical paths from the first polarizing beam splitter and the second polarizing beam splitter, respectively. 4. The optical switch according to claim 1, which uses PLZT as an electro-optical element. 5 A first polarized beam splitter that separates input light, and a plurality of second polarized beams that are arranged in series on the same straight line and input one polarized light output from the first polarized beam splitter to one end thereof. a beam splitter and a first total reflection prism which inputs the other polarized light outputted from the first polarizing beam splitter, the first total reflection prism being arranged in series on the same straight line;
a plurality of third polarizing beam splitters that input the outputs of the total reflection prisms at one end thereof; between a second total reflection prism outputting to the other end of the beam splitter and the first and plurality of second polarization beam splitters, and between the total reflection prism and the plurality of third polarization beam splitters; an electro-optical element disposed, and a half-wave plate disposed between the total reflection prism, the plurality of third polarizing beam splitters, and the plurality of first and second polarizing beam splitters, 1. An optical switch characterized in that the combination of first and second polarizing beam splitters through which light is input and output is switched by driving a predetermined electro-optical element. 6. The optical switch according to claim 2, wherein the beam splitter surfaces of the first polarizing beam splitter and the second and third polarizing beam splitters are arranged at right angles to each other. 7. The optical switch according to claim 2, wherein the optical switch is configured to input and output two optical paths from the first polarizing beam splitter and the second polarizing beam splitter, respectively. 8. The optical switch according to claim 2, which uses PLZT as the electro-optical element.