JP2003043386A - Optical switching system, and method for aligning of optical axis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a space connection type optical switching system, using a reflector which achieves reduction of optical loss, by optimally adjusting the optimum state of the reflector, and to provide a method for aligning the optical axis. SOLUTION: The optical switching system is provided with a first reflector 2a which can control an attitude for directing input light, a second reflector 2b which is disposed opposite to the first reflector and carries out an output by reflecting light reflected by the first reflector, and a means 5 to control each attitude of the first and second reflectors and to adjust the attitude of the controlled first and second reflectors. The optical switching system (a) generates a reference beam, the wavelength of which is substantially different from the input light, (b) reflects the generated reference beam by the first and second reflectors with the input light, (c) selectively branches the reference beam from reflected light to detect light intensity, and controls the attitude of the first and second reflectors, so that the intensity of the input light is maximized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch system for switching an optical signal used in a switch for optical communication, and more particularly to an optical switch system capable of multi-channelization by spatial switching by a three-dimensional matrix. The present invention relates to a switch system and an optical axis alignment method in such a system.

[0002]

2. Description of the Related Art Conventionally, with the development of an optical communication system using an optical fiber, an optical switch has been adopted as an exchange in such a system. In particular, a so-called matrix type optical switch, which is a multi-channel optical switch, is used with the recent increase in communication speed and capacity.

As an example of such a matrix type optical switch in the prior art, for example, Japanese Patent Application Laid-Open No. 2000-3300.
According to Japanese Patent Laid-Open No. 44-44, there is disclosed what is called a two-dimensional optical switch, which switches the connection of optical signals on a plane. The two-dimensional type optical switch according to the related art has a relatively simple structure, but since the optical fibers are arranged side by side on the plane, there is a limit to the number of channels, so that it is more compact and compact. In recent years, there has been a strong demand for an optical switch by spatial optical connection, that is, a three-dimensional type optical switch that can be realized.

Such a spatial connection type three-dimensional type optical switch has a structure in which collimated light is reflected by a mirror to switch the optical connection, as disclosed in, for example, Japanese Patent Laid-Open No. 2000-247065. Therefore, precise posture (position) control of the reflecting mirror is important. However, only the attitude control of the mirror based on the detection data from the angle sensor attached to the mirror cannot sufficiently absorb the thermal deformation of the housing, the positional displacement due to aging, and the error of the angle sensor. Therefore, the optical connection efficiency is lowered.

Therefore, in the conventional technique, generally, after the attitude of the mirror is roughly controlled by the angle control using the angle sensor, the optical signal is branched through the optical switch using the branch of the optical signal provided on the output system side. A few to several tens% of the communication data light is divided into a data light intensity evaluation PD (photodiode) and received.
The attitude of the mirror is finely adjusted so that the intensity of light received by the PD for evaluating the intensity of the data light is maximized.

[0006]

However, in the above-mentioned conventional optical switch, the difference in the light intensity between the input light and the output light causes the optical loss in the optical switch.
Generally, a standard is set in advance for the light intensity of communication light in an optical communication system. When the optical loss in the communication path including the optical switch is large, the light passing through the optical switch cannot be output as it is. For example, the optical intensity is amplified by using an optical amplifier. Is required, which makes the structure of the optical switching system complicated and large. Therefore, it is necessary to reduce the optical loss as much as possible.

By the way, as an optical loss source in such a space-connecting type optical switch utilizing a reflecting mirror, a connection loss of an optical fiber to the optical switch, a transmission loss of a collimating lens for collimating an input light, and a reflecting mirror are used. Reflection loss,
There are losses and the like at the time of re-imaging of collimated light on the output side. Therefore, in order to control the position of the reflecting mirror described above, when an optical branch is further provided, this causes the use of several to several tens% of the communication light. Therefore, as an optical loss source in the optical switch, It was very big.

Further, in order to confirm that the optical connection is in the optimum state, that is, that the light intensity is maximum, the reflecting mirror is intentionally shaken to some extent within the range where the optical connection is not lost. By changing it, it is necessary to search for the reflecting mirror posture that maximizes the light intensity. However, this method has a practical problem because the light intensity of the communication light also changes during the search for this optimum posture.

Therefore, in the present invention, in view of the above-mentioned problems in the prior art, that is, there is no optical loss even when the optimum attitude of the reflecting mirror is searched, the optical connection efficiency is excellent, and the switching equipment for optical communication and the like. Suitable for use in
In addition, an optical switch system capable of multiple channels and capable of being compact and downsized in response to high speed and large capacity in optical communication, and an optical axis alignment method in such a system are provided. The purpose is to provide.

[0010]

In order to achieve the above-mentioned object, according to the present invention, first, a plurality of input lights and a plurality of output lights corresponding thereto can be arbitrarily switched by spatial optical coupling. An optical switch system capable of: a posture-controllable first reflecting mirror to which input light is directed; a light arranged at a position facing the first reflecting mirror and reflected by the first reflecting mirror. A second reflecting mirror for outputting by reflecting; a means for controlling the attitudes of the first reflecting mirror and the second reflecting mirror respectively; and a reference whose wavelength is substantially different from that of the input light. An optical switch system is provided, which comprises means for adjusting the attitude of at least one of the first reflecting mirror and the second reflecting mirror controlled by the attitude control means by light.

Further, according to the present invention, in the above-mentioned optical switch system, the attitude adjusting means adjusts the light intensity of the input light with which the first reflecting mirror is irradiated and reaches the second reflecting mirror. The attitude of at least one of the first reflecting mirror and the second reflecting mirror is adjusted so as to maximize.

Further, according to the present invention, in the above-mentioned optical switch system, the attitude adjusting means includes a reference light emitted to the first reflecting mirror and a reference light reaching the second reflecting mirror. The attitude of at least one of the first reflecting mirror and the second reflecting mirror is adjusted by the difference in intensity.

Further, according to the present invention, in the above-mentioned optical switch system, the input side further includes a reference light generating means for generating the reference light and a multiplexer, and the optical multiplexer includes An optical demultiplexer that combines the input light and the reference light and irradiates the first reflecting mirror and selectively reflects the reference light to separate it from the input light is provided on the output side. And a light receiving means for detecting the light intensity of the reference light.

Further, according to the present invention, in the above-mentioned optical switch system, further, on the input side, reference light generating means for generating the reference light, and an optical multiplexer for combining the input light and the reference light. And a means for collimating the input light among the lights from the optical multiplexer and selectively irradiating the reference light with the reference light selectively radiated to the first reflecting mirror. It is provided with means for selectively detecting the reference light and detecting the irradiation position on the second reflecting mirror, and the attitude adjusting means is such that the reference light is the center on the second reflecting mirror. The posture of the first reflecting mirror is adjusted so that the area is irradiated.

In addition, according to the present invention, in the above-described optical switch system, the means for detecting the irradiation position of the reference light on the second reflecting mirror has a hole through which the input light passes in the central portion thereof. It is formed and a plurality of light receiving elements are arranged adjacent to each other around it.

In addition, according to the present invention, in the above-described optical switch system, the plurality of light receiving elements is four.

Further, according to the invention, in the above-mentioned optical switch system, an irradiation position of the dispersed reference light reflected by the second reflecting mirror is further provided in an optical path after the second reflecting mirror. In order to detect the above, a hole is formed in the center for passing the input light, and a light receiving element having a plurality of elements adjacent to each other is provided around the hole, and the attitude adjusting means includes the light receiving element. The attitude of the second reflecting mirror is adjusted based on the output of

Further, according to the present invention, in the above-described optical switch system, further, on the input side, reference light generating means for generating the reference light, and collimating the input light and at the same time from the reference light generating means And a means for irradiating the first reflecting mirror by superimposing the reference light of (1) on the same axis, and
On the output side, a photo-detecting element for selectively detecting the reference light from the light reflected by the first and second reflecting mirrors is provided, and the attitude adjusting means is provided from the photo-detecting element. The postures of the first and second reflecting mirrors are adjusted based on the output.

Further, according to the present invention, in the above-mentioned optical switch system, the photodetector element has a hole through which an input light passes in a central portion thereof, and a plurality of light receiving elements are adjacent to each other around the hole. It will be arranged.

Further, according to the present invention, in the above-described optical switch system, the plurality of light receiving elements forming the photodetecting element are four.

In addition, according to the present invention, in the above-mentioned optical switch system, the photodetector element further includes:
Means for selectively removing the reference light is provided.

Further, according to the present invention, in order to achieve the above-mentioned object, an optical switch system capable of arbitrarily switching a plurality of input lights and a plurality of output lights corresponding thereto by spatial optical coupling. A first reflecting mirror in which the attitude of the input light is controllable, and the first reflecting mirror is arranged so as to face the first reflecting mirror, and the light reflected by the first reflecting mirror is reflected to output. A second reflecting mirror, means for controlling the attitudes of the first reflecting mirror and the second reflecting mirror, respectively, and the first reflecting mirror and the second mirror controlled by the attitude controlling means. And a means for adjusting the attitude of at least one of the reflecting mirrors, the optical axis aligning method for aligning the optical axis of the input light, wherein (a) the wavelength thereof is substantially different from that of the input light. Generates reference light (B) reflecting the generated reference light together with the input light on at least one of the first and second reflecting mirrors; (c) selectively branching the reference light from the reflected light to increase the light intensity. There is provided an optical axis alignment method for an optical switch system, which comprises detecting and controlling the attitude of at least one of the first and second reflecting mirrors so that the intensity of the input light is maximized.

Further, according to the present invention, in the above optical axis aligning method, the steps (a) to (c) are performed,
This is performed during the switching operation of the optical switch system.

Further, according to the present invention, in the above-mentioned optical axis adjusting method, in the step (b), the reference light is coaxially overlapped with the input light as a center, and the first and second optical axes are overlapped. A method for aligning an optical axis of an optical switch system, which comprises irradiating at least one of the reflecting mirrors.

Further, according to the present invention, in the above-mentioned optical axis adjusting method, in the step (c), the reference light coaxially overlapped with the input light as a center is the first and second reference lights. 2. The optical axis alignment method for an optical switch system, wherein the attitudes of the first and second reflecting mirrors are controlled so as to be positioned at the center of at least one of the reflecting mirrors.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, FIG. 1 attached herewith shows a schematic structure of a so-called 2 × 2 optical matrix switch according to a first embodiment of the present invention. In the figure, reference numeral 1 is an optical switch system, 2a is a first reflecting mirror, 2b is a second reflecting mirror, 2c is a reflecting mirror surface, 3a is an input side collimating lens, and 3b is an output side collimating lens. A lens, 4 an optical matrix switch housing, 5 a mirror attitude control circuit, 5
a is a mirror drive signal, 5b is a mirror angle signal, 5c
Is a mirror drive driver, 6 is a reference light intensity detection circuit,
6a is a reference light source, 6b is a light receiving element, 6c is a reference light intensity signal, 7a is a multiplexer, 7b is a demultiplexer, 7c is a reference light wavelength band reflection type filter, and 8 is reference light. The optical path,
Reference numeral 9 is a communication optical path, 10a is an input connector, 10b is an output connector, and 11 is an optical switch switching circuit.
1a shows the optical switch switching signals, respectively.

In this embodiment, two reflecting mirrors 2a and 2b are provided, and an angle sensor (not shown) for measuring the angle of each mirror is attached to each reflecting mirror 2a, 2b. . The attitude data of the reflecting mirrors 2a and 2b corresponding to the optical paths between the input and output are, respectively,
The initial value is stored in the mirror attitude control circuit 5 in advance. Further, in this figure, one of the two optical paths from the input to the output is omitted in order to make the figure easy to see and understand.

In the figure, the broken line shows the optical path 8 of the reference light including the inside of the optical fiber, while the thick solid line without the arrow shows the optical path 9 of the communication light also including the inside of the optical fiber. Usually, light in the wavelength band of 1200 nm to 1600 nm is used as this communication light, and more specifically, light in the 1310 nm band or 1550 nm band is widely used, and as the light source, for example, a semiconductor laser is used. Are suitable.

On the other hand, as the reference light, a wavelength band of 1000 nm or less clearly and substantially different from that of the above-mentioned communication light is provided so as not to be included in the above-mentioned communication light as noise, that is, in order to improve its separability. Of light. In particular, 68
By using a visible light laser of 0 nm or less, since a commercially available semiconductor laser can be used as the light source, the light source can be obtained at a relatively low cost. Also as a photodetector used to detect the light, a semiconductor light receiving element (Photo
It is particularly preferable to use an inexpensive Si-based diode as the diode (hereinafter referred to as PD).

As the demultiplexer 7b, for example, a wavelength selective reflective filter used in a video camera or the like can be used. Since the commercially available technology can be applied in this manner, the system can be realized at a relatively low cost. The collimator lenses 3a and 3b are lenses for obtaining parallel light or light rays close to it from the output light from the optical fiber forming the optical path in the system. For example, this is a combination of a plurality of lenses. Alternatively, it is often configured by using a refractive index variable lens or a rod lens.

The communication light that has passed through the input side collimator lens 3a is directed to the corresponding first reflecting mirror 2a immediately below it. On the other hand, the light reflected by the second reflecting mirror 2b is controlled so as to be directed to the corresponding output side collimator lens 3b immediately above the second reflecting mirror 2b, so that both light rays are in a positional relationship parallel to each other. In addition, since the above-mentioned reflecting mirror has a wavelength band of light used as communication light of 1200 nm to 1600 nm, which is in a so-called infrared region, it is particularly formed of gold as a flat film. Although ideal, instead of this, a film made of aluminum can obtain a high reflectance for the communication light in the infrared region, so that the reflecting mirror can be formed of an aluminum film. , Economically advantageous.

Further, in order to drive the above-mentioned reflecting mirrors 2a and 2b, it is general to use an attraction force by an electrostatic force, a force by a piezo effect, an electromagnetic force or the like. In particular, the driving method using electrostatic force has an advantage that the driving current can be small, and the method using electromagnetic force has an advantage that a strong driving force can be generated.

Next, the operation of the optical switch system whose configuration has been described above will be described with reference to the attached FIG. Note that FIG. 2 particularly shows a flowchart of the optical axis alignment method in the optical switch system.

First, when an optical switch switching signal 11a for instructing the optical switch system to connect a certain input to an appropriate output is output from the outside and input to the optical switch switching circuit 11 (step S2).
1), the mirror attitude control circuit 5 performs reflection based on the data obtained from the angle sensor attached to the reflecting mirror based on the data of the initial attitude of the reflecting mirror which is preset and stored therein. A command is issued to the driver 5c to change the attitude of the mirror.
The driver 5c drives the reflecting mirrors 2a and 2b to take the initial posture of the reflecting mirrors stored in advance (step S2).
2).

According to the above mirror attitude control, the communication light 9 input from the outside through, for example, an optical fiber is used.
Is combined with the reference light 8 (see the broken line in FIG. 1) generated by the reference light source 6a in the multiplexer 7a.
After being collimated by the collimator lens 3a, the combined light is reflected by the first reflecting mirror 2a, goes to the second reflecting mirror 2b, and is further reflected by the second reflecting mirror 2b.
Then, this light is guided again into the optical fiber provided as a waveguide in the system by the output side collimator lens 3b.

Thereafter, the combined light guided into the optical fiber is guided into the inside of the optical demultiplexer 7b, and a filter (reference light wavelength band) provided therein for reflecting light in the wavelength band of the reference light is provided. Due to the function of the reflection filter, only the reference light is separated and taken out, and is also guided to the light receiving element 6b via, for example, an optical fiber. On the other hand, the optical demultiplexer 7
The communication light that has passed through b is output to the outside via the output side connector 10b.

The reference light wavelength band reflection filter of the optical demultiplexer 7b has a wavelength transmission characteristic as shown in FIG. 3, for example. That is, this reflection filter has 12
Efficient demultiplexing is made possible by transmitting communication light in the wavelength band of 00 nm to 1600 nm while reflecting the reference light having a wavelength in the visible light band of 680 nm or less without transmitting it.

As an example of the structure of the optical demultiplexer 7b, for example, as shown in the attached FIG. 4, quartz or Si is used.
In the middle of the straight line portion of the waveguide 12 made of the substrate or organic resin, the slit 1 is slightly inclined with respect to this straight line.
4 is formed, and a thin film-shaped reference light wavelength band reflection type filter 13 is inserted therein. Furthermore, this slit 14
The reference light waveguide 16 is provided in the opposite direction by inclining the same angle (θ) as the angle (θ) 15 of the waveguide 12 to be formed.

According to the optical demultiplexer 7b having such a structure, the communication light traveling (propagating) in the waveguide 12 is transmitted through the filter 13 and output, while the reference light is the reference light. The light is totally reflected at 13, and is guided into the reference light waveguide 16. In addition, as the principle of the demultiplexer, there are methods such as using an MZ type demultiplexer and a prism.

Next, the reference light intensity signal 6c received by the light receiving element 6b is compared and verified by the reference light intensity detection circuit 6. Here, there is a possibility that the angle of the initial position of the reflector, which is already stored in the mirror attitude control circuit 5, may be displaced due to displacement due to temperature, aging, noise, and the like. Therefore, the initial position (angle) does not always provide the optimum optical connection.

Then, returning to FIG. 2 again, the angle of the reflecting mirror is slightly moved (step S23). Then, it is determined whether or not the reference light received by the light receiving element 6b has the maximum light intensity (step S24). If it is determined that the reference light intensity is maximum (yes) by this determination, the reflection angle previously stored in the mirror attitude control circuit 5 is used by using the angle of the reflecting mirror that maximizes the reference light intensity. The mirror initial position is corrected (step S24), and the series of switching processes is completed (step S25). On the other hand, when the reference light intensity is not the maximum (no) in the determination process of the above step S24, the process returns to the above step S23 again, and the above steps S23 and S24.
Is repeated until the intensity of the reference light reaches the maximum value.

As described above, according to the optical axis aligning method in the optical switch system of the present invention, the reference light intensity received by the light receiving element 6b is intentionally changed by finely moving the angle of the reflecting mirror. By doing so, the angle of the reflecting mirror that maximizes the light intensity in the reference light intensity detection circuit 6 is determined. When the angle (position) of the reflecting mirror that produces the maximum light intensity is determined, the position is stored as a new initial position.

According to the optical axis aligning method described above, during the next switching operation in the optical switch system,
It is possible to start from a value closer to the reflector angle (position) of maximum light intensity. Note that the embodiment shown here is one in which the present invention is applied to a 2 × 2 matrix switch, but by adjusting the conditions such as the maximum drive angle of the reflecting mirror, the parallelism of collimated light, and dispersion. Further, it can be applied to a multi-channel optical switch system. For example, in the case of 32 ch × 32 ch, in the calculation, the distance between adjacent reflecting mirrors is about 2 mm, the distance between the first and second reflecting mirrors is about 100 mm, and the driving angle of the reflecting mirrors is about ± 10 °. is necessary.

As is apparent from the above, according to the optical switch system of the present invention, even if the optical path connection in the system is determined once (for example, at the time of shipping the product), the optimum reflecting mirror attitude is determined, the actual optical path connection can be realized. The position (angle) shift of the reflecting mirror that has awesomeness caused by temperature changes etc. in the use environment can be always set to the optimum posture by the optical axis alignment method described above. Although the communication light output intensity varies slightly, the optimum optical connection condition can be obtained.

Next, FIG. 5 shows a schematic configuration of a matrix type optical switch system according to a second embodiment of the present invention. It should be noted that, also in this figure, one of the two optical paths from the input to the output is omitted in order to make the figure easier to see and understand.

Also in the second embodiment, the positional relationship between each collimator lens and the reflecting mirror is the same as that described above. However, in the present embodiment, the material of the collimator lenses 3a and 3b is intentionally
The difference in refractive index depending on the wavelength, that is, the one with large chromatic aberration is used. When a collimator lens made of such a material is used so as to obtain parallel light in the wavelength band of communication light, or light close to it, the reference light which is the other light used in this system is It is collimated by the collimator lens, but as a result of its chromatic aberration, the communication light 17 is
The light 18 is diffused around (the thick solid line in the figure). Further, in this embodiment, neither the first nor the second reflecting mirrors 2a and 2b are provided with an angle sensor, however, these may be provided if necessary.

In the above configuration, as is clear from the figure, the reflecting mirror surface 2c of the first reflecting mirror 2a is large enough to reflect all the reference light 18 diffused in the collimator lens 3a ( Area, but on the other hand, the reflecting mirror surface 2c of the second reflecting mirror 2b is sufficient to reflect all the communication light 17 which is not diffused by the collimator lens described above, however, the diffused reference The light 18 is large enough to reflect a part thereof.

On the front surface of the second reflecting mirror 2b, as shown in FIG. 6 attached, a four-division light receiving element 19 having a hole large enough to pass the communication light 17 which is not diffused is provided. , Is installed parallel to the second reflecting mirror surface. for that reason,
A part of the reference light 18 diffused by the collimator lens 3a cannot pass through the hole of the four-division light receiving element 19 and is blocked. Therefore, the position of the diffused reference light 18 can be determined by comparing the intensities of the reference lights received by the respective portions of the four-division light receiving element 19, and the above-mentioned non-diffused communication light can be determined. Since 17 passes through the central portion of this diffused reference light 18, the position of this communication light 17 can also be estimated. Therefore, by utilizing the position of the communication light 17 that can be estimated, the attitude of the first reflecting mirror 2a is determined by the communication light 17
It can be controlled so that it is correctly directed to the reflecting surface 2c of b. In addition, the four-division light receiving element 19 includes the reflecting mirror 2b.
It is placed in a position that does not prevent the change of posture.

This method will be described in more detail with reference to the attached FIG. First, assuming that the direction from the input side collimator lens 3a to the corresponding first reflecting mirror 2a is the vertical direction, the axial direction perpendicular to the vertical direction in the mirror surface 2c of the first reflecting mirror 2a and the second Reflector 2
The axial direction perpendicular to the vertical direction in the mirror surface 2c of b is parallel to each other, for example, from the positional relationship of the reflecting mirrors corresponding to the collimator lenses described in the embodiment shown in FIG. I also understand. Therefore, when the collimated communication light 17 is directed to the center of the reflecting mirror surface, the received light intensity of the reference light 18 on the four-division light receiving element 19 arranged as shown in FIG. It should be.
However, as illustrated in FIG. 7 described above, when a large amount of the diffused reference light 18 strikes the right side of the four-division light receiving element 19, the attitude of the first reflecting mirror 2a is set to the collimated communication light. It can be seen that it may be adjusted so that 17 moves to the left side of the figure.

The vertical adjustment of the communication light 17 will be described below. It should be noted that, as shown in FIG. 7 described above, the difference in distance from the first reflecting mirror 2a causes
The light intensity of the reference light 18 on the split light receiving element 19 is not vertically symmetrical. However, the communication light 17 is reflected by the reflecting mirror 2b.
If the difference (value) of the light intensity of the reference light 18 detected by the elements in the vertical direction of the four-division light receiving element 19 when it comes to the center of , The first reflecting mirror 2 described above without providing an angle detector.
It is possible to correct the vertical angle of a. It should be noted that this means that even if the positional relationship between the collimator lens and the reflecting mirror is different from that of the present embodiment, and the reference light intensities are not equal to the left and right, by applying the same method as above,
It is possible to accurately control the attitude of the first reflecting mirror.

After that, a part of the collimated communication light 17 and reference light 18 reflected by the second reflecting mirror 2a is
It is directed toward the corresponding output side collimating lens 3b. Then, according to the present embodiment, in front of the output side collimator lens 3b (on the side of the second reflecting mirror 2b),
Further, a four-divided light receiving element 20 is also arranged in which a hole having a minimum diameter for allowing the collimated communication light 17 to pass therethrough is opened in the central portion thereof. Ie, here too,
By the same method as the attitude control of the first reflecting mirror by the four-division light receiving element with a hole 19 provided immediately before the second reflecting mirror 2b, which is described in detail above, the second reflecting mirror 2 is also controlled.
The attitude control of b can be performed.

As described above, according to the attitude control of the reflecting mirror using the four-divided light receiving elements 19 and 20 with holes, the communication light passes through the holes of these elements, so that it is shown in FIG. The light loss can be suppressed as compared with the embodiment. The reference light 18 imaged by the output-side collimator lens 3b is usually sufficiently small, but by providing a filter for blocking the reference light on the front surface of the output-side collimator lens 3b, It is also possible to more reliably prevent the reference light from entering the output as noise.

As described above, the split light receiving elements 19 and 20 detect the reference light close to visible light, and these light receiving elements are made of Si, which is widely used in various electronic devices. Since these semiconductor light receiving elements can be formed, these elements can be formed better and cheaper. It should be noted that, in the above-described embodiment, specifically, as the divided light receiving elements 19 and 20, only an example in which a light receiving element with a hole of four divisions is used has been described, but in principle, it is divided into four. Instead of the light receiving element with holes, for example, a light receiving element with three holes may be used. However, in this case, in order to obtain the position shift direction from these divided light receiving elements, in addition to simple comparison calculation, other calculation is also required, and the calculation is required, so that the operation delay and the circuit are reduced. It is expected that obstacles such as complication will occur, and from this reason as well, the four-division light receiving element is more preferably used.

Further, FIG. 9 shows a schematic structure of a matrix type optical switch system according to a third embodiment of the present invention. In the embodiment shown in FIG. 9 as well, as in the case of the embodiment shown in FIG. 5, only one optical path is shown and the others are shown in order to make the drawing easier to see and understand. Omitted.

In the matrix type optical switch system of the third embodiment, as is clear from the figure, in the optimum optical path state, instead of the multiplexer 7a and the collimator lens 3a, reference is made to collimated communication light. A collimated communication light / coaxial reference light generator 21 that coaxially combines light is used. In addition, the first reflecting mirror 2 from the creator 21
The perpendicular drawn to a and the perpendicular drawn from the output collimator lens 3b to the second reflecting mirror 2b are also parallel, however, in this embodiment, the direction is different from that of the above-mentioned embodiment. The opposite (downward). According to such a configuration, the plane including the first reflecting mirror surface 2a and the plane including the second reflecting mirror surface 2b are defined by the reflecting mirrors 2a and 2a.
The relationship is point-symmetrical with respect to the midpoint of the optical path between b.

That is, in the third embodiment, unlike the embodiment shown in FIG. 5, both the light striking near the center of the reflecting mirror and the light striking near the outer edge of the reflecting mirror are collimated communication light / coaxial reference light generators. The optical path lengths from 21 to the collimating lens for output become equal. Therefore, as shown in the attached FIG. 11, a reference beam 1 collimated into a parallel beam on a concentric circle with respect to a communication beam 17 collimated into a parallel beam.
By irradiating 8, the reference light impinges on the upper surface of the four-divided light receiving element 20 with a hole arranged in front of the collimating lens 3b on the output side becomes circular as shown in the attached FIG. That is, the reference light intensities of the respective light receiving elements become equal. Therefore, the collimated communication light 17 can be directed to the center of the hole only by controlling the attitude of the reflecting mirror so that the light intensity detected by each light receiving element of the four-division light receiving element 20 becomes equal. it can. That is, the adjustment by comparison with the received light intensity distribution in the optimum state described in the embodiment of FIG. 5 becomes unnecessary,
It is suitable. Further, it goes without saying that the light projection pattern 18 of the reference light is not limited to the above-described circular shape, and the same effect can be obtained even if it is an elliptical shape that is line-symmetrical in the vertical direction and the horizontal direction on the reflecting mirror surface.

Further, as described above, in the structure of the third embodiment, the plane including the first reflecting mirror surface 2a and the plane including the second reflecting mirror surface 2b have a point-symmetrical positional relationship. Therefore, the control can be simplified by controlling the postures of both mirror surfaces to be point-symmetrical.

The collimated communication light 17 in the collimated communication light / coaxial reference light generator 21 and the reference light 18 coaxial with the collimated communication light 17 are shown in FIG. 10 attached herewith. As shown in the figure, the communication light beam 17 collimated into a parallel beam by the input-side collimator lens 3a has a 45 ° angle in the middle thereof.
The wavelength selective transmission / reflection filter 23 is arranged at an angle of 10 °, while from the direction of 90 ° with respect to the communication light 17, it is created by the collimated reference light generator 22 and The reference light 18a collimated into a parallel beam having a circular cross section with a diameter larger than the beam diameter is irradiated so that the center of the reference light 18a comes to a point where the communication light 17 passes through the wavelength selective transmission / reflection filter 23. In addition, the wavelength selective transmission / reflection filter 23 has, for example, communication light 1
The light of the wavelength band of 7 (1200 nm to 1600 nm) is transmitted, but the wavelength band of the reference light 18a (1000 nm or less)
Choose a ray that reflects light. Specifically, a filter having the same wavelength characteristic as the reference light wavelength band reflection type filter 7c in FIG. 1 is suitable.

As described above, in the optical switch system according to the present invention, the light of the wavelength band different from the communication light is used as the reference light for the precise positioning of the reflecting mirror. Since the wavelength bands are different, the reference light and the communication light cannot be confused because they cannot be separated from each other even if they pass through the same optical path. In this way, by using a system that detects only the reference light that has passed through the same optical path as the communication light for axis alignment, it is possible to reduce the loss of the communication light. In addition,
In order to superimpose the reference light and the communication light, generally,
A multiplexer is required, but the only loss of communication light in this multiplexer is the transmission loss. Further, instead of optical branching, for example, a demultiplexer is required, but by providing a filter function that transmits or reflects only a specific wavelength, it is possible to suppress the attenuation of communication light and separate only reference light. It will be possible. Since this separated reference light passes through the same optical path as the communication light, the intensity of this reference light is checked, and the attitude of the reflecting mirror is controlled based on that intensity, so that the optical connection in the system is improved. It is possible to adjust and control the attitude of the reflector so that it is optimal.

Furthermore, the reference light is collimated by selecting an input-side collimator lens having a large chromatic aberration and making the aberration of the reference light in the wavelength band significantly different from that of the communication light. The communication light is mainly used, and the light is more diffused. On the other hand, in the second reflecting mirror on the output side, at least three or more (preferably four) around the hole where the portion corresponding to the reflecting mirror surface is cut out.
The light receiving element divided into parts is arranged. According to this, the reference light and the communication light are reflected by the first mirror and directed to the second reflecting mirror, but only the communication light collimated here passes through the above-mentioned hole and the second reflecting mirror. Part of the diffused reference light that reaches the
It is detected by three or more light receiving elements arranged around this hole. Then, the direction of the first reflecting mirror can be estimated depending on which light receiving element has a higher received light intensity, the attitude of the first reflecting mirror is controlled, and the communication light reflected by the first reflecting mirror is accurately reflected to the second direction. It can be pointed at the reflector.

On the input side of the output side collimator lens for forming the image of the collimated light, that is, on the second reflecting mirror side,
A light receiving element having a hole large enough to allow the collimated communication light to pass therethrough and having the periphery of the hole divided into at least three or more (preferably four) portions is arranged. Thereby, when the attitude of the second reflecting mirror is not proper, a part of the communication light or the reference light reflected by the second reflecting mirror is
By controlling the attitude of the second reflecting mirror based on the light detected by these light receiving elements, the communication light reflected by the second reflecting mirror can be accurately directed to the image forming collimator lens. That is, using the above method, it is not necessary to use a demultiplexer on the optical output side, and it is possible to further reduce the attenuation of communication light in the optical switch system.

In the above embodiments, only the example in which the present invention is applied to the optical switch system which is a 2 × 2 optical matrix switch has been described, but the present invention is not limited to this and the present invention is not limited to this. Can also be applied to, for example, an N × N optical matrix switch.

[0064]

As is apparent from the above detailed description, according to the present invention, there is no optical loss even when the optimum attitude of the reflecting mirror is searched, optical connection efficiency is excellent, and optical communication and the like are achieved. An optical switch system that is suitable for use as a switchboard, capable of multi-channelization in response to high speed and large capacity in optical communication, and is compact and compact Then, it becomes possible to provide an optical axis alignment method in such a system.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of a 2 × 2 optical matrix switch, which is an optical switch system according to a first embodiment of the present invention.

2 is a flow chart showing an optical axis alignment method in the optical switch system shown in FIG. 1 of the present invention.

3 is a diagram showing a graph of a wavelength transmittance curve of a reference light wavelength band reflection filter of the optical demultiplexer in the optical switch system shown in FIG.

FIG. 4 is a diagram showing an example of the configuration of an optical demultiplexer using the reflection filter having the characteristics shown in FIG.

FIG. 5 is a diagram showing a schematic structure of a matrix switch which is an optical switch system according to a second embodiment of the present invention.

FIG. 6 is a view of the optical switch system shown in FIG.
It is sectional drawing which shows the positional relationship of the 4 division light receiving element with a hole, and a 2nd reflecting mirror.

FIG. 7 is a diagram showing a case of using the four-division light receiving element shown in FIG.
It is a figure explaining the principle of the position control of the light in the optical switch system of the said FIG.

8 is a sectional view showing a positional relationship between a four-division light receiving element and an output-side collimator lens in the optical switch system of FIG.

FIG. 9 is a diagram showing a schematic structure of a matrix switch which is an optical switch system according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a configuration example of a collimated communication light / coaxial reference light generator used in the third embodiment.

11 is a diagram showing a pattern example of light projection by the collimated communication light / coaxial reference light generator shown in FIG.

12 is a diagram showing an example of a state of a surface on which the light from the collimated communication light / coaxial reference light generator shown in FIG. 10 hits the four-division light receiving element.

[Explanation of symbols]

1 ... Optical switch system, 2a ... First reflecting mirror system, 2b ... Second reflecting mirror system, 2c ... Reflecting mirror surface, 3a ... Input side collimating lens, 3b ...・ Output side collimator lens, 4 ・ ・ ・ Optical matrix switch housing, 5 ・
..Mirror attitude control circuits, 5a ... Mirror drive signals, 5b
..Mirror angle signals, 5c ... Mirror drive driver, 6 ...
Reference light intensity detection circuit, 6a ... Reference light light source, 6b ... Light receiving element, 6c ... Reference light intensity signal, 7a ... Multiplexer, 7b ...
Demultiplexer, 7c ... Reference light wavelength band reflection type filter, 8 ...
Reference light optical path, 9 ... Communication light optical path, 10a ... Input connector, 10b ... Output connector, 11 ... Optical switch switching circuit, 11a ... Optical switch switching signal, 12 ... Waveguide Linear portion, 13 ... Thin film reference light wavelength band reflection type filter, 14 ... Slit, 15 ... Angle formed by slit and waveguide linear portion, 16 ... Reference light waveguide, 17 ... Collimated communication light, 18 ... Diffused reference light, 18
a ... Collimated reference light, 19 ... Quadrant light receiving element with second reflecting mirror hole, 19a ... Hole of four division light receiving element with second reflecting mirror hole, 20 ... Output collimating lens 4-division light receiving element with front hole, 21 ... Collimated communication light
Coaxial reference light generator, 22 ... Collimated reference light generator,
23 ... Wavelength selective transmission / reflection filter plate

Claims (16)

[Claims] 1. An optical switch system capable of arbitrarily switching between a plurality of input lights and a plurality of corresponding output lights by spatial optical coupling: a posture controllable input light directing direction. One reflecting mirror; a second reflecting mirror that is arranged so as to face the first reflecting mirror and outputs the light reflected by the first reflecting mirror; and the first reflecting mirror; Means for respectively controlling the attitude of the second reflecting mirror; and the first reflecting mirror and the first reflecting mirror controlled by the attitude controlling means by reference light whose wavelength is substantially different from that of the input light. An optical switch system comprising means for adjusting the attitude of at least one of the second reflecting mirrors. 2. The optical switch system according to claim 1, wherein the attitude adjusting unit has a maximum light intensity of the input light that is irradiated on the first reflecting mirror and reaches the second reflecting mirror. The optical switch system is characterized by adjusting the posture of at least one of the first reflecting mirror and the second reflecting mirror. 3. The optical switch system according to claim 1, wherein the attitude adjusting means has the intensities of the reference light emitted to the first reflecting mirror and the reference light reaching the second reflecting mirror. An optical switch system, wherein the attitude of at least one of the first reflecting mirror and the second reflecting mirror is adjusted by the difference. 4. The optical switch system according to claim 1, further comprising a reference light generating means for generating the reference light and a multiplexer on the input side, the optical multiplexer comprising:
An optical demultiplexer that synthesizes the input light and the reference light, irradiates the first reflecting mirror, and selectively reflects the reference light to separate it from the input light; An optical switch system comprising: a light receiving unit that detects the light intensity of the generated reference light. 5. The optical switch system according to claim 1, further comprising a reference light generating unit for generating the reference light on the input side, and an optical multiplexer for combining the input light and the reference light. And a means for collimating the input light of the light from the optical multiplexer and selectively dispersing the reference light to irradiate the first reflecting mirror, and the output side includes the dispersed reference. A means for selectively detecting light to detect an irradiation position on the second reflecting mirror is provided, and the attitude adjusting means is configured such that the reference light is a central portion on the second reflecting mirror. The optical switch system is characterized in that the attitude of the first reflecting mirror is adjusted so that the first reflecting mirror is illuminated. 6. The optical switch system according to claim 5, wherein the means for detecting the irradiation position of the reference light on the second reflecting mirror has a hole through which the input light passes in the central portion thereof. , An optical switch system comprising a plurality of light receiving elements arranged adjacent to each other around the light receiving element. 7. The optical switch system according to claim 6, wherein the plurality of light receiving elements is four. 8. The optical switch system according to claim 5, wherein an irradiation position of the dispersed reference light reflected by the second reflecting mirror is further provided in an optical path after the second reflecting mirror. For the purpose of detection, a hole is formed in the center for passing the input light, and a light receiving element having a plurality of elements adjacent to each other is provided around the hole, and the attitude adjusting means is provided with the light receiving element of the light receiving element. An optical switch system, wherein the attitude of the second reflecting mirror is adjusted based on an output. 9. The optical switch system according to claim 1, further comprising: a reference light generating unit that generates the reference light on the input side, and collimates the input light and outputs the reference light from the reference light generating unit. A means for irradiating the first reflecting mirror by superimposing the reference light on the same axis is provided, and on the output side, the reference light is selected from the light reflected by the first and second reflecting mirrors. Equipped with a photodetector that detects
The attitude adjusting means adjusts the attitudes of the first and second reflecting mirrors based on the output from the photodetector. 10. The optical switch system according to claim 9, wherein the photodetector element has a hole at the center thereof for passing input light, and a plurality of light-receiving elements are adjacent to each other around the hole. An optical switch system characterized by being arranged. 11. The optical switch system according to claim 10, wherein the plurality of light receiving elements forming the photodetecting element are four. 12. The optical switch system according to claim 10, wherein the photodetector element is further provided with means for selectively removing the reference light. 13. An optical switch system capable of arbitrarily switching a plurality of input lights and a plurality of output lights corresponding thereto by spatial optical coupling, wherein an attitude control in which the input light is directed is possible. One reflecting mirror, a second reflecting mirror which is arranged so as to face the first reflecting mirror and outputs the light reflected by the first reflecting mirror, and the first reflecting mirror and A means for controlling the attitude of each of the second reflecting mirrors, and a means for adjusting the attitude of at least one of the first reflecting mirror and the second reflecting mirror controlled by the attitude controlling means. In the optical switch system, the optical axis alignment method for aligning the optical axes of the input light includes: (a) generating reference light having a wavelength substantially different from that of the input light; (b) generating the reference light. Together with the input light And (c) the reference light is selectively branched from the reflected light to detect the light intensity, and the intensity of the input light is maximized. A method for aligning an optical axis of an optical switch system, comprising controlling the attitude of at least one of the first and second reflecting mirrors. 14. The optical axis of an optical switch system according to claim 13, wherein the steps (a) to (c) are performed during a switching operation of the optical switch system. How to match. 15. The optical axis aligning method according to claim 13, wherein in the step (b), the reference light is coaxially overlapped with the input light as a center, and the first and second reflections are combined. A method for aligning an optical axis of an optical switch system, which comprises irradiating at least one of mirrors. 16. The optical axis aligning method according to claim 15, wherein in the step (c), the reference light superposed coaxially with the input light as a center is the first and second light beams. 2. The optical axis alignment method for an optical switch system, wherein the attitudes of the first and second reflecting mirrors are controlled so as to be positioned at the center of at least one of the reflecting mirrors.