JP3040883B2 - Multi-terminal optical switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a function of arbitrarily changing the order of the optical paths of a plurality of light beams propagating in space.
The present invention relates to a multi-terminal optical switch that can be used for an optical switch or the like.

[0002]

2. Description of the Related Art A two-input / two-output unit switch is connected in multiple stages, and a one-to-one connection is established between N input terminals and N output terminals.
As a switch to be connected, there is a matrix switch based on a crossbar type configuration. FIG. 1 shows a wiring diagram of a matrix switch having N inputs and N outputs (specifically, 8 inputs and 8 outputs) as an example. In FIG. 1, a solid line indicates a wiring in the network.
The rectangles in the figure are unit switches having two inputs and two outputs, which are controlled by an external device to connect input-output 1, input 2-output 2 (through), input 1-output 2, and input 2-output. One of two connection forms (cross) of the output 1 is adopted. In order to connect the input signal from the i-th input terminal in the drawing to the j-th output terminal using this switch, a unit switch (see FIG. 1) located at the intersection of the i-th input terminal and the j-th output terminal In the drawing, the hatched unit switches) are in a cross state, and the other unit switches connected to the i-th input terminal or the j-th output terminal (unit switches in the area within the dashed line frame in the figure) ) May all be in a through state.

This matrix switch has an advantage that a switch network having N input terminals and N output terminals can be realized with a simple configuration, and a signal propagation path in the network can be set easily and unblocked. However, since N ² unit switches are required for the number of terminals N, the number of components becomes very large as N increases. In addition, when the signal is attenuated when passing through the unit switch, the number of unit switches passing therethrough becomes very large as N increases, so that there is a disadvantage that the passage loss increases accordingly.

[0004] In contrast, the unit switches with two inputs and two outputs connected cascade, to realize all combinations of connecting one-to-one between the 2 ^N pieces of input terminals and the 2 ^N output terminals that A switch network configuration method has been devised. FIG.
Is a wiring diagram of a switch network of 32 inputs and 32 outputs based on the above configuration method. The solid line in FIG. 2 indicates the wiring in the network. The rectangle is a unit switch having two inputs and two outputs, and a connection form (through) between input 1 and output 1 and input 2 and output 2 and input 1 and output 2 and input 2 and output 1 are controlled by external control. It takes either one of the connection forms (cross).

The circuit network shown in FIG. 2 has a configuration in which switch stages in which unit switches are arranged in an array and wiring networks connecting adjacent switch stages are alternately arranged. In the case of FIG.
The switch network is composed of nine switch stages and eight wiring networks. In general, the switch network of the form is extended to easily constructed having the 2 ^N input terminals and the 2 ^N output terminals. At this time, the switch network has 2 ^N-1 per stage.
(2N-1) unit switch arrays each including one unit switch, and one of the outputs of each unit switch for one, two, and four switches in the next-stage switch array. Wiring networks connected to the unit switches whose positions are spatially shifted by ^N-2 pieces are formed by a total of (2N-2) wiring networks in two stages.

As a multi-terminal optical switch that optically realizes the above-mentioned switch network, an academic paper, “Relocatable multi-channel free-space optical switch (Ar
earrangeable multichannel free-space opticalswitch
based on multistage network configuration) ", IEEEE J. Lightwave Tec
h.), Vol. 9, pages 1726-1732, are known.

FIG. 3 shows a configuration of a multi-terminal optical switch described in the above-mentioned document. In FIG. 3, reference numerals 1-1 and 1-2 denote collimated optical signal input terminals for inputting the collimated optical signal to the switch body. Reference numerals 2-1 and 2-2 denote polarization beam splitters that transmit the horizontally polarized light (P wave) as it is and reflect the vertically polarized light (S wave) in the 90 ° direction on the internal reflection surface. Reference numerals 3-1 to 3-x denote liquid crystal spatial light modulator arrays, each of which has a function of switching the rotation angle of the polarization plane of light transmitted through each cell to 0 ° or 90 ° for each cell. 4-
Numerals 1 to 4-x denote polarization routing elements, which spatially shift the incident beam according to the polarization state thereof, and perform the same function as the wiring network of FIG. Reference numerals 5-1 and 5-2 denote collimated optical signal receiving terminals for receiving a collimated optical beam transmitted through the switch. In this switch, each cell of the liquid crystal spatial light modulator array 3 is a unit switch, and input and output to the unit switch are two linearly polarized lights orthogonal to each other, so that the rotation of the polarization plane of the passing light beam can be changed by the unit switch. It corresponds to the operation.

[0008] The P-wave optical signal emitted from the collimated optical signal input terminal 1-1 and the S-wave optical signal emitted from the collimated optical signal input terminal 1-2 are converted into a polarization beam splitter 2-1.
And incident on the switch body. The polarization plane of the optical signal incident on the switch body is controlled by the liquid crystal spatial light modulator array 3, the optical path is shifted by the polarization routing element 4 depending on the polarization state, and finally has the target position and polarization state. The light exits from the switch body as a collimated light beam. The light beam emitted from the switch body is separated into a P-wave optical signal and an S-wave optical signal by the polarization beam splitter 2-2, and the P-wave component and the S-wave component are collimated optical signal receiving terminals 5-1 and 5 respectively. -2
Received by

As the routing element 4 applied to this switch, the elements shown in FIGS. 4A to 4C are disclosed. In FIG. 4, reference numeral 11 denotes a birefringent crystal, for example, calcite is used. Reference numeral 12 denotes a polarization plane conversion element array, which is an element having a function of exchanging horizontal polarization and vertical polarization such as a half-wave plate and an optical rotator (hatched portion in the figure), and a polarization plane exchange function of a normal glass plate and the like. And the element having no (the white area in the figure) are alternately arranged. 13 is a polarization beam splitter, and 14 is a glass rod of the same size as the polarization beam splitter 13. FIG. 4A shows a birefringent crystal.
It has a structure in which a polarization plane conversion element array 12 is inserted between 11. FIG. 4B shows a structure in which the polarization plane conversion element array 12 is inserted between the polarizing beam splitters 13 which are stacked and arranged in an array. FIG. 4C shows a structure in which a first polarizing beam splitter array in which the polarizing beam splitters 13 are stacked and a second polarizing beam splitter array in which the polarizing beam splitters 13 and the glass rods 14 are alternately stacked. have.

FIG. 4 shows the optical paths of the incident horizontal polarized light (solid line) and vertical polarized light (dashed line) in the device. Regarding any of the elements, it can be seen that one polarized light component passes through the element without being shifted, and the other polarized light component is shifted and the optical paths are exchanged with each other. The magnitude of the shift of the optical path at this time is equal to the magnitude of the shift of the extraordinary ray due to the birefringent crystal 11 in FIG. 4A, and the length of one side of the polarization beam splitter 13 in FIGS. 4B and 4C. Equal to Therefore, by changing these sizes, the shift amount of the optical path can be adjusted, and a routing element having an interval between adjacent beams twice, four times,... Can be manufactured.

[0011]

The optical switch described in the above document is a switch for a polarization multiplexed optical signal which travels along the same optical path and has different signals in each of horizontal polarization and vertical polarization. Therefore, when the input collimated light beam has an arbitrary polarization state or the polarization state changes with time, this switch cannot be applied as it is. As one of the methods for making the present optical switch applicable to an optical signal having such an arbitrary polarization, the horizontal polarization component and the vertical polarization component of one optical signal are regarded as independent optical signals,
The paths in these switches are set independently, and finally these are spatially combined as a horizontal polarization component and a vertical polarization component propagating in the same optical path, and emitted from a target channel as one light beam. It is possible. According to this method, an optical signal that has spatially entered the switch as one light beam can be output again from the target channel as one light beam. However, if the propagation times of the paths through which the two separated optical signals are combined in the switch are different between the separated optical signals, the jitter due to the difference in propagation time when combining the separated optical signals will be reduced. Occurs and adversely affects the propagation of high-speed optical signals.

[0012]

According to the present invention, as described above, the present invention can be applied to a high-speed optical signal by applying a switch configuration in which the propagation time difference between two optical signals separated inside the switch is removed. It is intended to realize an optical switch that operates stably without being affected by jitter.

According to the present invention, there is provided means for arranging a number of optical paths of collimated incident signal light in a grid or in a line and in parallel to enter the switch body, and for all of a plurality of light beams, It has the function of separating into two orthogonal linearly polarized light components, moving the optical path of one of the linearly polarized light components, combining this with the linearly polarized light component of the other light beam that is not moved, and propagating on the same optical path. A plurality of optical path conversion elements and a plurality of polarization plane control elements that are controlled to either pass the two linearly polarized light components orthogonal to each other of the light beam as they are or to exchange these linearly polarized light components with each other A polarization plane control element array, and the polarization plane control element array and the optical path conversion element are alternately arranged on the optical path of the plurality of collimated light beams incident into the switch body. A multi-terminal optical switch in which the polarization plane control element is operated so that the linearly polarized light component is always emitted from the same optical path to the outside of the switch main body. The above-mentioned polarization plane control element so that the path from the polarization plane control element array that is incident immediately after being separated from the light beam to the polarization plane control element array that is incident immediately before being combined into the same optical path is always the same. Operates, and the sum of the time required for the two light beams to pass through the optical path conversion element that separates the light beams and the optical path conversion element that combines the light beams always becomes the sum of the two light beams. The above two optical path conversion elements are characterized in that they have a function of equalizing the propagation time between them.

According to another aspect of the present invention, the optical path conversion element having the propagation time equalizing function transmits one of two linearly polarized beams orthogonal to each other as it is and reflects the other in a direction perpendicular to the traveling direction. A first polarizing beam splitter array in which a plurality of polarizing beam splitters having the same shape are stacked in the traveling direction of the reflected linearly polarized light, the first polarizing beam splitter array having the same shape as the polarizing beam splitter array, and A second polarization beam splitter array arranged so that the reflection directions of the linearly polarized light beams are opposite to each other, and a function of exchanging polarization planes of the two linearly polarized light beams that are sandwiched between the two beam splitter arrays and pass therethrough. And a polarization plane rotation element having the following.

Further, according to the present invention, the optical path-changing element having the propagation time equalizing function transmits one of two linearly polarized beams orthogonal to each other as it is and reflects the other in a direction perpendicular to the entering direction. A first polarizing beam splitter array in which a plurality of polarizing beam splitters having the same shape are stacked in the traveling direction of the reflected linearly polarized light, and a first polarizing beam splitter having the same shape as the polarizing beam splitter, and A second polarizing beam splitter array in which polarizing beam splitters arranged so that the reflecting directions of the polarizing beams are opposite to each other are stacked transparently via a spacer having the same shape and the same refractive index as the polarizing beam splitter,
A polarizing beam splitter array having the same shape as the first polarizing beam splitter array, and a polarizing beam having the same shape as the first polarizing beam splitter array and arranged so that the reflection direction of the linearly polarized beam is reversed. A third polarizing beam splitter array that is combined with the splitter array and that is entirely rotated at right angles to the first or second polarizing beam splitter array with the direction of light entering as an axis. Features.

[0016]

The present invention eliminates the propagation time difference between two optical signals separated inside the switch by limiting the arrangement of the routing elements inside the switch, and clearly shows a method of limiting the difference. In this respect, it is clearly different from the prior art.

Embodiments of the present invention will be described in detail with reference to the drawings.

[0018]

FIG. 5 shows an embodiment of the present invention. In FIG. 5, reference numeral 101 denotes a collimated optical signal 4 × 4 input terminal for inputting the collimated optical signal to the switch body.
102-1 to 102-x are liquid crystal spatial light modulator arrays, and the rotation angle of the plane of polarization of light passing through each internal cell is set to 0 ° for each cell.
Or has a function to switch to 90 °. 103-1, 103-2
Is an optical signal propagation time equalization type polarization routing element. The polarization is configured such that the horizontal polarization component and the vertical polarization component incident from the same optical path have the same propagation time when passing through these two elements. It is a pair of routing elements. Reference numerals 104-1 to 104-6 denote ordinary polarization routing elements, which spatially shift the incident light beam according to the polarization state thereof and perform the same function as the wiring network of FIG. Ten
Reference numeral 5 denotes a collimated optical signal receiving terminal for receiving a collimated optical beam transmitted through the switch.

FIG. 6 is a wiring diagram showing an optical signal path in the switch body shown in FIG. The configuration is such that the switch stages at both ends are removed from the wiring diagram shown in FIG.
Two adjacent inputs respectively correspond to a horizontal polarization component and a vertical polarization component input from one of the collimated optical signal input terminals in FIG. 5, and two adjacent outputs correspond to FIG.
Corresponds to the horizontal polarization component and the vertical polarization component received by one of the collimated optical signal receiving terminals. The wiring networks at both ends in FIG. 6 correspond to the polarization routing elements 103-1 and 103-2 in FIG. 5 and the intermediate portions thereof are the liquid crystal spatial light modulator arrays 102-1 to 102-2. -7 and a portion composed of ordinary polarization routing elements 104-1 to 104-6.

As shown in FIG. 6, an intermediate portion of the switch network has a configuration in which two switch networks having exactly the same configuration shown by hatching in the figure are arranged in parallel. By the way, signals from two adjacent input terminals of the switch network of FIG. 6 are separated into two by a first-stage wiring network, and distributed one by one to both of the intermediate-stage switch networks arranged in parallel. These signals are independently routed in each intermediate stage and output, and then combined again by the final stage wiring network and output from two adjacent output terminals. At this time, the two separated signals enter from the same position in each intermediate stage and exit from the same position. Therefore, if all the unit switches in each intermediate stage are set to be in the same state as each other, the two separated signals proceed along the same path in the respective incident intermediate stages. Will be done. Thus, these two signals pass through the intermediate stage with equal propagation times.

On the other hand, the wiring networks at both ends in FIG. 6 are portions corresponding to the polarization routing element of the optical signal propagation time equalization type.
As described with reference to FIG. 5, if the two separated signals pass through the input-side and output-side optical signal transit time equalizing type optical routing elements with the same transit time, they pass through the switch body. The propagation times required to pass can be completely matched.

FIG. 7 shows a first configuration example of the polarization routing element of the optical signal propagation time equalization type. FIG. 7A shows the configuration, and FIG. 7B shows the optical path. FIG. 7 is a diagram for explaining the combination of input / output in each set, with eight input / output ports in the upper two stages and eight input / output ports in the lower two stages as one set. In FIG. 7, the routing element in the middle part is omitted, but as described above, in the middle part, the light beam passing therethrough depends on the exit position from the exit-side routing element to finally reach. The path setting of the light beam is performed in exactly the same way between the upper two stages and the lower two stages, and its polarization plane is converted. In FIG. 7A, reference numeral 21 denotes a collimated optical signal input terminal, and reference numeral 22 denotes a polarization beam splitter. Reference numeral 23 denotes a polarization plane conversion element array, which has a function of exchanging horizontal polarized light and vertical polarized light such as a half-wave plate and an optical rotator (hatched portion in the figure);
It has a structure in which elements such as a normal glass plate or the like that do not have a polarization plane exchange function (the white portions in the figure) are alternately arranged. Reference numeral 24 denotes a collimated optical signal receiving terminal. In this configuration, the input-side routing element includes a polarizing beam splitter that shifts the S wave upward by a distance equal to the length of one side of the polarizing beam splitter 22 and a polarizing beam splitter that shifts the S wave.
22 has a structure in which a polarization plane conversion element array is inserted between a polarization beam splitter array that shifts downward by a distance equal to the length of one side, and the input-side routing element is arranged above and below the input-side routing element. It has an inverted structure. Since the configuration of each individual routing element is the same as that shown in FIG. 4B, each of them has the same function as the first and last wiring networks in FIG.

Here, there are the following four routes of the optical signal output from the collimated optical signal input terminal 21 and output to the collimated optical signal receiving terminal. Upper half of collimated optical signal input terminal 21 → Upper half of collimated optical signal receiving terminal 24, Upper half of collimated optical signal input terminal 21 → Lower half of collimated optical signal receiving terminal 24, Lower half of collimated optical signal input terminal 21 → Upper half of collimated optical signal receiving terminal 24, lower half of collimated optical signal input terminal 21 → lower half of collimated optical signal receiving terminal 24,

Table 1 shows the optical path lengths of the P wave and the S wave propagating in the polarization beam splitter array in each case.

[Table 1]

Here, d is the length of one side of the polarizing beam splitter 22. As is clear from Table 1, the above
In all cases, the optical path lengths of the incident P-wave and S-wave in the polarization beam splitter are equal to each other. More generally, when this configuration is used, the S-polarized light exits from the upper port, and the P-polarized light exits from the lower port, regardless of the incident position of the incident-side routing element. When the light beams incident from the same position are compared with each other, the light beam emitted upward always passes through the optical path longer by d than the light beam emitted downward. On the other hand, in the exit-side routing element, when comparing the light beams emitted from the same position, the light path that is always incident from the upper side has an optical path shorter by d than the light beam that is incident from the lower side regardless of the emission position. pass. As a result, as shown in Table 1, the optical path length difference between the P-polarized light and the S-polarized light in both the routing elements is canceled, and as a result, the propagation times of the two separated optical signals become equal. It is.

Here, the switch network shown in FIG. 2 or FIG. 6 is symmetrical when viewed from the center switch stage, and
Unit switches 1, 2, ..., 2 for ^N inputs / outputs
If the wiring networks for shifting by ^N-2 are all complete, the functions will be the same as those shown in the figure, even if the arrangement order of the wiring networks is different from that in the figure. For example, a switch network in which the arrangement order of the wiring networks is reversed as shown in FIG.
It has the same function as the switch network.

FIG. 9 shows a first example of the configuration of an optical signal propagation time equalizing type polarization routing element corresponding to such a wiring network.
The shape is as shown in In FIG. 9, reference numeral 21 denotes a collimated light signal input terminal, 22 denotes a polarization beam splitter, and 23 denotes a polarization plane conversion element array. Reference numeral 24 denotes a collimated optical signal receiving terminal. In the case of the configuration shown in FIG. 9, in the incident-side routing element, the light beams incident from the same position are emitted evenly at the height of the odd-numbered row of the collimated optical signal input terminal regardless of the incident position. In the routing element on the emission side, the light beam emitted from the same position always passes through the optical path longer by d than the light beam emitted at the height of the second row, and the collimated optical signal receiving terminal is always independent of the emission position. Since the light beam incident from the height of the odd-numbered row passes through an optical path shorter by d than the light beam incident from the height of the even-numbered row, the optical path length difference between both the routing elements becomes smaller. The cancellation results in equal propagation times of the two separated optical signals. Here, d is the length of one side of the polarization beam splitter 22.

In the configuration examples of FIGS. 7 and 9, even when the routing elements on the input side and the output side of the optical signal are exchanged, the propagation times until the separated optical signals are combined again are equal. It is obvious. 7 and 9
The present invention also includes a configuration in which the routing elements on the incident side and the output side are replaced with each other in the configuration example described above. Although FIGS. 7 and 9 show the case where two vertical stages are replaced for simplicity, the matrix-like input / output ports can be replaced by increasing the number of stages and using a plurality of routing elements rotated by 90 °.

FIG. 10 shows a second configuration example of the polarization routing element of the optical signal propagation time equalization type. This is a configuration corresponding to the switch network of FIG. FIG. 10A shows the configuration, and FIG. 10B shows an optical path. In FIG. 10A, 31 is a collimated optical signal input terminal, and 32 is a polarization beam splitter. Reference numeral 33 denotes a transparent rod made of a material having the same refractive index as the constituent material of the polarization beam splitter 32 and having the same shape as the polarization beam splitter 32. Reference numeral 34 denotes a collimated optical signal receiving terminal.

The configuration of the routing element shown in FIG. 10 is such that the polarizing beam splitter 32 is provided after the element shown in FIG.
A polarization beam splitter array composed only of the above components is obtained by rotating the polarization beam splitter array at right angles about the incident direction of light. However, since the polarization beam splitter array added at the subsequent stage is rotated at a right angle about the incident direction of light, the P wave to the routing element becomes an S wave to the polarization beam splitter array added. It should be noted that The polarization beam splitter array added at the subsequent stage shifts only the S wave for the array twice in the opposite direction by the length d of one side of the beam splitter. Therefore, the light beam passing through this array does not undergo any position shift, but its S-wave component passes through the optical path longer by 2d than the P-wave component. That is, the polarizing beam splitter array has a function of correcting an optical path difference between the P wave and the S wave by the routing element at the preceding stage.

Here, there are the following four routes of the optical signal input from the collimated optical signal input terminal 21 and output to the collimated optical signal receiving terminal. Upper half of collimated light input terminal 31 → Upper half of collimated light signal receiving terminal 34, Upper half of collimated light input terminal 31 → Lower half of collimated light signal receiving terminal 34, Lower half of collimated light input terminal 31 → Collimated light signal Upper half of receiving terminal 34, lower half of collimated optical input terminal 31 → lower half of collimated optical signal receiving terminal 34,

Table 2 shows the optical path lengths of the P wave and the S wave propagating in the polarizing beam splitter array in each case.

[Table 2]

As is evident from Table 2, the optical path lengths of the incident P-wave and S-wave in the polarizing beam splitter in all of the above cases are equal to each other. More generally, when this configuration is used, in the incident-side routing element, the light beam incident from the same position is such that the light beam emitted downward regardless of the incident position is the light beam emitted upward. Than the light beam emitted from the same position, it passes through an optical path shorter by d than the light beam emitted from the same position, so that the optical path length difference between both routing elements is canceled. As a result, the propagation times of the two separated optical signals become equal.

FIG. 11 shows a second example of the configuration of an optical signal propagation time equalizing polarization routing element different from that of FIG. FIG.
FIG. 11A shows the configuration, and FIG. 11B shows an optical path.
In FIG. 11A, reference numeral 31 denotes a collimated optical signal input terminal, and reference numeral 32 denotes a polarization beam splitter. Reference numeral 33 denotes a transparent rod made of a material having the same refractive index as the constituent material of the polarization beam splitter 32 and having the same shape as the polarization beam splitter 32. Reference numeral 34 denotes a collimated optical signal receiving terminal.

The configuration shown in FIG. 11 is such that the front part of the optical signal propagation time equalization type polarization routing element on the output side in FIG. 10 is rotated by 180 ° about an axis perpendicular to the plane of the paper. FIG.
As is clear from the optical path diagram of FIG. 2B, even with such a configuration, in the exit-side routing element, the light beam emitted from the same position always reflects the light beam incident from below regardless of the emission position. Is more d than the light beam incident from above
Passes only a short optical path. Therefore, even in the configuration of FIG.
As in the case of 10, the propagation times of the two separated optical signals can be made equal.

FIGS. 10 and 11 show a structure in which a polarizing beam splitter array for correcting the optical path length is added after the routing element having the structure shown in FIG. 4C. Since no element for rotating the polarization plane is used, this optical path length correcting polarization beam splitter array has a structure as shown in FIGS. 12 (a) and 12 (c).
It is also possible to adopt a configuration in which it is installed in the preceding stage of the routing element having the above configuration or in the middle thereof.

As a configuration corresponding to the switch network of FIG. 8, a configuration of a routing element as shown in FIG. 13 is also possible. In the case of this configuration, the routing element on the incident side
Regarding the light beam incident from the same position, the light beam emitted at the even-numbered row height of the collimated optical signal input terminal is always higher than the light beam emitted at the odd-numbered row height regardless of the incident position. In the routing element on the emission side, which passes through the optical path long by d and emits from the same position, the light beam always enters from the height of the even-numbered row of the collimated optical signal receiving terminal regardless of the emission position. Pass through the optical path shorter by d than the light beam incident from the height of the odd-numbered row, so that the optical path length difference in both the routing elements is canceled, and the two separated optical signals are separated. Are equal. Therefore, the configurations of FIGS. 12 and 13 are also included in the present invention. Further, by using the element rotated by 90 °, it is possible to switch the input / output ports in a matrix.

[0038]

As described above, in the multi-terminal optical switch according to the present invention, since the propagation time difference between the two separated optical signals is eliminated inside the switch, the jitter can be reduced even for high-speed optical signals. An optical switch that operates stably without being affected by the above is realized.

[Brief description of the drawings]

FIG. 1 is a wiring diagram of an N-input N-output (8 × 8) matrix switch.

FIG. 2 is a wiring diagram of a switch network of a multistage network configuration having 32 inputs and 32 outputs.

FIG. 3 is a diagram showing a configuration of a conventional light beam multi-terminal space switch.

FIG. 4 is a diagram showing a configuration of a routing element applied to the multi-terminal optical switch shown in FIG.

FIG. 5 is a diagram showing one embodiment of the present invention.

FIG. 6 is a wiring diagram showing an optical signal path in the switch main body shown in FIG. 5;

FIGS. 7A and 7B are diagrams showing a first configuration example of an optical signal propagation time equalization type polarization routing element, in which FIG. 7A shows the configuration and FIG. 7B shows an optical path in the element.

FIG. 8 is a wiring diagram showing an optical signal path in a switch body having a configuration different from that of FIG. 5 or FIG. 6, based on another embodiment of the present invention.

FIG. 9 is a diagram showing a first configuration example of an optical signal propagation time equalization type polarization routing element based on FIG. 8;

FIGS. 10A and 10B are diagrams showing a second configuration example of an optical signal propagation time equalization type polarization routing element, where FIG. 10A shows the configuration and FIG. 10B shows an optical path in the element.

11 is a diagram showing a second configuration example of an optical signal propagation time equalization type polarization routing element different from the case of FIG. 10; FIG. 11 (a) shows the configuration; FIG.

FIG. 12 is a diagram showing a configuration of a polarization routing element different from FIG. 10 based on a second configuration example of the optical signal propagation time equalization type polarization routing element.

FIG. 13 is a diagram showing a second configuration example of the optical signal propagation time equalization type polarization routing element based on FIG. 8;

[Explanation of symbols]

1-1, 1-2 Collimated light signal input terminal 2-1, 2-2 Polarization beam splitter 3-1-3-x Liquid crystal spatial light modulator array 4-1-4-x Polarization routing element 5-1, 5 -2 Collimated optical signal receiving terminal 11 Birefringent crystal 12 Polarization plane conversion element array 13 Polarization beam splitter 14 Glass rod 21 Collimated optical signal input terminal 22 Polarization beam splitter 23 Polarization plane conversion element array 24 Collimated optical signal reception terminal 31 Collimated optical signal Input terminal 32 Polarizing beam splitter 33 Transparent rod 34 Collimated optical signal receiving terminal 101 Collimated optical signal input terminal 102-1 to 102-x Liquid crystal spatial light modulator array 103-1, 103-2 Optical signal propagation time equalization type polarization routing Element 104-1 to 104-x Normal polarization routing element 105 Collimated optical signal receiving terminal

──────────────────────────────────────────────────続 き Continued on the front page (56) References Journal of Lightwave Technology, Vol. 9 No. 12 (December 1991) pp. 1727-1732 (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/29-3/00 G02F 1/13 505 H04Q 3/52-3/52 101 H04B 10/00-10/14

Claims (3)

(57) [Claims] 1. A means for arranging the optical paths of a plurality of collimated incident signal lights in a grid or in a row and in parallel to enter a switch main body, and making the light beams orthogonal to all of the plurality of light beams. An optical path conversion having a function of separating into two linearly polarized light components, moving the optical path of one of the linearly polarized light components, and combining this with the linearly polarized light component of the other light beam which is not moved, and propagating on the same optical path. An element and polarized light having a plurality of polarization plane control elements arranged to either pass two linearly polarized light components orthogonal to each other of the light beam as they are or to exchange these linearly polarized light components with each other. A plane control element array, wherein the polarization plane control element array and the optical path conversion element are alternately arranged on the optical path of the plurality of collimated light beams incident into the switch body. A multi-terminal optical switch in which the polarization plane control element is operated so that the linearly polarized light component always exits the switch body from the same optical path. The polarization plane control elements are arranged such that the path from the polarization plane control element array that is incident immediately after being separated from the light beam to the polarization plane control element array that is incident immediately before being combined into the same optical path always has the same shape. Operating, the sum of the time required for the two light beams to pass through the optical path conversion element for separating the light beams and the optical path conversion element for combining the light beams is always between the two light beams. A multi-terminal optical switch, characterized in that the two optical path conversion elements are configured to have a propagation time equalizing function that becomes equal. 2. An optical path conversion element having a propagation time equalizing function, wherein one of two linearly polarized beams orthogonal to each other is transmitted as it is, and the other is reflected in a direction perpendicular to the traveling direction. A first polarizing beam splitter array in which a plurality of polarizing beam splitters having the same shape are stacked in the traveling direction of the reflected linearly polarized light; and the linearly polarizing beam having the same shape as the polarizing beam splitter array. A second polarizing beam splitter array arranged so that the reflection directions of the two linearly polarized light beams are opposite to each other, and a polarized light beam having a function of exchanging polarization planes of the two linearly polarized light beams that are sandwiched between the two beam splitter arrays and pass therethrough. The multi-terminal optical switch according to claim 1, comprising a surface rotating element. 3. An optical path changing element having a propagation time equalizing function, wherein one of two linearly polarized beams orthogonal to each other is transmitted as it is, and the other is reflected in a direction perpendicular to an entering direction thereof. A first polarizing beam splitter array in which a plurality of polarizing beam splitters having the same shape are stacked in the traveling direction of the reflected linearly polarized light; and a first polarizing beam splitter array having the same shape as the polarizing beam splitter. A second polarizing beam splitter array in which polarizing beam splitters arranged so as to have opposite reflection directions are laminated via a transparent transparent spacer having the same shape and the same refractive index as the polarizing beam splitter; A polarizing beam splitter array having the same shape as the beam splitter array, and having the same shape as the first polarizing beam splitter array, and A polarization beam splitter array arranged so that the reflection direction of the linearly polarized light beam is reversed is combined, and the whole is perpendicular to the first or second polarization beam splitter array with the light entering direction as an axis. 3. The multi-terminal optical switch according to claim 1, further comprising: a third polarization beam splitter array that is rotated.