JP2005062831A - Optical switch and method of controlling the optical switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical switch which does not cause crosstalks to be generated for an output optical fiber upon switching operation. <P>SOLUTION: The optical switch 100 has an input optical fiber 11, a plural number of output optical fibers 18, a grating 15 that deflects the optical beam from the input optical fiber 11 into different directions for each wavelength component, a convex lens 14 that changes the optical beam from the grating 15 into a convergent optical beam, a movable mirror array 17 which directs the convergent optical beam from the convex lens 14 to one of the plurality of output optical fibers 18, a shutter array 16 arranged in front of the movable mirror array 17 and a control circuit 120 that controls the movable mirror array 17 and the shutter array 16. The movable mirror array 17 has a plurality of movable mirrors 17a, and the shutter array 16 has the same number of shutters 16a as that of the movable mirrors 17a. The shutter 16a properly intercepts the light beam traveling toward the movable mirrors 17a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical switch for changing the connection of optical signals, and more particularly to an optical switch that utilizes deflection of light by a movable mirror.

  US Patent Application Publication No. 2002 / 0196520A1 discloses an optical switch capable of switching the connection between an input optical fiber and an output optical fiber for transmitting a wavelength-multiplexed signal for each wavelength. The apparatus can be applied to MUX (multiplexer), DEMUX (demultiplexer), and optical switch depending on the number of input optical fibers and output optical fibers.

In this optical switch, the light from the input optical fiber is converted into parallel light, then demultiplexed by a grating, and irradiated to the MEMS mirror for each wavelength as convergent light through a lens. By changing the direction of the MEMS mirror, the reflected light follows a path different from that of the input light and is coupled to an output optical fiber at a position different from that of the input optical fiber. Thereby, the output destination optical fiber can be selected for each wavelength by changing the direction of the MEMS mirror.
US Patent Application Publication No. 2002 / 0196520A1

  In an optical switch, when switching the specific light that is incident or coupled to the output optical fiber from the current output optical fiber to another output optical fiber (switch operation), the output optical fiber before switching and the output after switching Unless the optical fiber is adjacent, the light from the input optical fiber is coupled to an intermediate output fiber that is not related to the switch operation in the process of changing the direction of the MEMS mirror.

  That is, the optical switch disclosed in US Patent Application Publication No. 2002 / 0196520A1 generates crosstalk with respect to an output optical fiber that is not related to the switching operation. Crosstalk may cause malfunction of the optical communication system, and it is desirable to prevent it as much as possible.

  The present invention has been made in consideration of such a situation, and its main object is to provide an optical switch that does not generate crosstalk with respect to an output optical fiber during a switching operation.

  The present invention is directed, in part, to an optical switch. The optical switch of the present invention includes at least one input optical fiber, a plurality of output optical fibers, and at least for selectively directing a light beam from the input optical fiber to any one of the output optical fibers. A movable mirror and at least one shutter for appropriately blocking a light beam directed from the input optical fiber to the movable mirror, the movable mirror having a changeable direction, and the movable mirror When the direction of is changed, the output optical fiber to which the light beam reflected by the movable mirror is combined is switched, and the shutter is a light beam directed toward the movable mirror while the direction of the movable mirror is changed. Shut off.

  The present invention is directed, in part, to a method for controlling an optical switch. The control method of the present invention includes at least one input optical fiber, a plurality of output optical fibers, and at least for selectively directing a light beam from the input optical fiber to any one of the output optical fibers. An optical switch control method comprising one movable mirror and at least one shutter for appropriately blocking a light beam directed from the input optical fiber to the movable mirror, and changing the orientation of the movable mirror Before starting, the step of closing the shutter to block the light beam toward the movable mirror, the step of changing the direction of the movable mirror while the shutter is closed, and the direction of the movable mirror After the change is completed, the shutter is opened to allow the light beam to enter the movable mirror.

  According to the present invention, an optical switch that does not generate crosstalk with respect to an output optical fiber during a switching operation is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment This embodiment is directed to an optical switch that switches wavelength-multiplexed signal light for each wavelength. FIG. 1 shows the configuration of the optical switch according to the first embodiment of the present invention.

  As shown in FIG. 1, the optical switch 100 of this embodiment includes a single input optical fiber 11 to which wavelength-multiplexed signal light (light including a plurality of wavelength components) is input, and a plurality of optical outputs. An output optical fiber 18; a collimating lens 12 that converts a divergent light beam emitted from the input optical fiber 11 into a parallel light beam; and an output light that converts the parallel light beam directed to the output optical fiber 18 into a convergent light beam. It has the same number of converging lenses 19 as the fibers 18.

  The optical switch 100 further includes a convex lens 13 that converts the parallel light beam from the collimating lens 12 into a convergent light beam, a convex lens 14 that converts the divergent light beam once converged from the convex lens 13 into a parallel light beam, and And a grating 15 for deflecting the parallel light beam in different directions for each wavelength component.

  The grating 15 constitutes a spectroscope that separates incident wavelength-multiplexed light based on the wavelength. The parallel light beam deflected by the grating 15 enters the convex lens 14 and is converted into a convergent light beam.

  The optical switch 100 is further disposed in front of the movable mirror array 17, that is, near the incident side of the light beam, for directing the convergent light beam from the convex lens 14 to one of the plurality of output optical fibers 18. The shutter array 16 includes a movable mirror array 17 and a control circuit 120 that controls the shutter array 16.

  The movable mirror array 17 has a plurality of movable mirrors 17a corresponding to the types of wavelengths multiplexed in the signal light. The shutter array 16 has the same number of shutters 16 a as the movable mirrors 17 a of the movable mirror array 17. Each of the shutters 16a corresponds to the movable mirror 17a, and appropriately blocks a light beam directed to the movable mirror 17a.

  In the optical switch 100, wavelength-multiplexed signal light, that is, light including a plurality of wavelength components is input to the input optical fiber 11. The light emitted from the input optical fiber 11 becomes a divergent light beam, passes through the collimating lens 12, and is converted into a parallel light beam. The parallel light beam from the collimating lens 12 passes through the convex lens 13 and is converted into a convergent light beam. This convergent light beam once converges and then becomes a divergent light beam. The diverging light beam passes through the convex lens 14 and is converted into a parallel light beam, and enters the grating 15. The light beam incident on the grating 15 is deflected in different directions for each wavelength component by the diffraction action of the grating 15 and is divided into light beams having a plurality of wavelength components. In other words, the light incident on the grating 15 is separated for each wavelength.

  A light beam having one wavelength component is converted into a convergent light beam by passing through the convex lens 14 and is directed to one movable mirror 17 a of the movable mirror array 17. If the shutter 16a of the shutter array 16 corresponding to the movable mirror 17a is in an open state, the convergent light beam directed to the movable mirror is converged near the movable mirror and reflected by the movable mirror.

  The direction (normal direction) of the movable mirror 17a can be changed within a predetermined range around one axis. That is, the movable mirror 17a can rotate around one axis within a predetermined angle range. The direction of the movable mirror 17a is controlled by the control circuit 120. Thereby, the direction of the light beam reflected by the movable mirror 17a can be adjusted. As a result, the light beam reflected by the movable mirror 17 a can be directed to one of the plurality of output optical fibers 18.

  The light beam reflected by the movable mirror 17a is converted into a parallel light beam through the convex lens 14, deflected by the grating 15, and again passes through the convex lens 14 to be converted into a convergent light beam. This convergent light beam once converges, then becomes a divergent light beam, passes through the convex lens 13 and is converted into a parallel light beam. When the direction of the movable mirror 17a is appropriately adjusted, the parallel light beam passes through the converging lens 19 and is converted into a converging light beam, and is output to one of the output optical fibers 18, for example, the uppermost output in FIG. The optical fiber 18 is entered. Light entering the output optical fiber 18 is output from the output optical fiber 18.

  The output optical fiber 18 into which the light beam reflected by the movable mirror 17a enters depends on the direction (deflection angle) of the movable mirror 17a. That is, the output optical fiber 18 into which the light beam reflected by the movable mirror 17a enters can be selectively switched by changing the direction of the movable mirror 17a.

  Since the operation of such an optical switch is similar to that described in, for example, US Patent Application Publication No. 2002 / 0196520A1, the detailed description thereof is omitted here.

  FIG. 2 shows a movable mirror array 17 used in the optical switch of FIG. The movable mirror array 17 includes a plurality of mirrors 23 aligned in a row, a pair of frames 21 extending on both sides along the arrangement of the mirrors 23, and a plurality of hinges 22 connecting the mirror 23 and the frame 21. And have. Each of the mirrors 23 is connected to two frames 21 through two hinges 22 extending in a straight line. Since the hinge 22 can be relatively easily twisted, the mirror 23 can change the direction within a predetermined angle range with the hinge 22 as an axis.

  The movable mirror array 17 includes a drive electrode (not shown) separately provided on the back side of each mirror 23 and a fixed electrode (GND electrode) (not shown) provided on the back side of the mirror 23. Thus, the direction of the mirror 23 can be changed by an electrostatic force generated by applying a voltage between the drive electrode and the fixed electrode.

  Such a movable mirror that can be electrostatically driven can be manufactured using MEMS (Micro Electro Mechanical System) technology, and is also introduced in, for example, Japanese Patent Application Laid-Open Nos. 2001-174724 and WO01 / 61400A2. Detailed explanation is omitted here.

  FIG. 3 shows the shutter array 16 used in the optical switch of FIG. One shutter 16a in the shutter array 16 includes a flat light-shielding part 31 for shielding light, a beam part 32 that supports the light-shielding part 31, and a fixing part 33 that cantilever-supports the beam part 32. Have. The light shielding portion 31 is joined to the free end of the beam portion 32 and extends substantially perpendicular to the beam portion 32. In this specification, “substantially vertical” means being exactly vertical and being nearly vertical. The beam portion 32 is relatively soft and can be elastically bent and deformed. With the bending deformation of the beam portion 32, the light shielding portion 31 moves in the vertical direction of FIG.

  The shutter 16a further includes a permanent magnet 34 disposed above the beam portion 32 at an interval, a drive line 35 provided on the beam portion 32, and a pad 36 for supplying current to the drive line 35. doing. The permanent magnet 34 and the drive line 35 constitute a drive unit that moves the light shielding unit by bending and deforming the beam unit.

  When a current is supplied to the drive line 35, the beam portion 32 is bent upward and deformed in FIG. 3 due to an electromagnetic force caused by the interaction between the current flowing through the drive line 35 and the magnetic field formed by the permanent magnet 34. 31 is moved upward. Further, when the supply of current to the drive line 35 is stopped, the bending deformation of the beam portion 32 disappears, and the light shielding portion 31 returns to the original position. In other words, the shutter 16a is driven by an electric signal, that is, an electric current, and the light shielding unit 31 can be moved up and down in FIG. 3 by controlling the electric signal, that is, the electric current. In the shutter array 16, the light shielding portion 31, the beam portion 32, the drive line 35, and the pad 36 can be easily and integrally manufactured by the MEMS technology.

  FIG. 4 is a perspective view of the movable mirror array 17 and the shutter array 16. As shown in FIG. 4, the mirrors 23 of the movable mirror array 17 and the light shielding portions 31 of the shutter array 16 are arranged at the same pitch. In a state where the beam portion 32 is not bent and deformed, the light shielding portion 31 is located just in front of the mirror 23.

  5A shows the “closed state” of one shutter 16a of the shutter array 16, and FIG. 5B shows the “open state” of the shutter 16a. As shown in FIG. 5A, the shutter 16 a is in a “closed state” in which the beam portion 32 does not bend and deform, and the light shielding portion 31 is positioned just in front of the mirror 23 in the state where the electric signal is not supplied. For this reason, the light beam heading substantially from the front to the mirror 23 is blocked by the light blocking portion 31 positioned in front of it. Further, in the supply state of the electric signal, as shown in FIG. 5B, the beam portion 32 is bent and deformed, and the light shielding portion 31 is moved upward to be in the “open state” where it is removed from the front of the mirror 23. For this reason, the light beam that is directed substantially from the front to the mirror 23 can be incident on the mirror 23 without being blocked by the light shielding portion 31. That is, the light beam is allowed to enter the mirror 23.

  4, 5 </ b> A, and 5 </ b> B, the wiring (feeding line from the outside) for driving the shutter array 16 and the movable mirror array 17 is not shown. However, in order to avoid mechanical interference, the wiring is used as the shutter. The array 16 may be connected from above, and the movable mirror array 17 may be connected from below.

  Next, a switching operation in the optical switch of the present embodiment, that is, an operation of selectively switching the output optical fiber by the movable mirror while suppressing the occurrence of crosstalk will be described with reference to the flowchart of FIG. Here, as an example, a case where the output channel is switched from the top output optical fiber 18 to the third output optical fiber 18 in FIG. 1 will be described.

  Normally, all the shutters of the shutter array 16 are in an open state in a state where optical signals are passed. That is, all the shutter arrays 16 are in a state where power is supplied to the drive lines 35.

  When a switch command is given to the control circuit 120 from an upper controller (not shown) (S601), the control circuit 120 stops supplying power to the drive line 35 of the shutter 16a corresponding to the wavelength to be switched, and the shutter is closed. (S602). Thereafter, the control circuit 120 gives a drive signal to the corresponding movable mirror, that is, the movable mirror 17a paired with the shutter that has been closed earlier, and the third output optical fiber 18 whose light beam is a new output destination. The direction of the movable mirror 17a is controlled so as to be directed to the right (S603).

  At this time, since the shutter 16a is in the closed state, the light beam from the input optical fiber 11 is blocked by the light blocking portion 31, and does not reach the movable mirror 17a. For this reason, the reflected light beam from the movable mirror 17a is not generated while the direction of the movable mirror 17a is changed. Accordingly, the light beam from the movable mirror 17a does not reach any of the output optical fibers 18 and further the input optical fiber 11. As a result, it is possible to avoid the occurrence of crosstalk with respect to the optical fiber that is not related to the switching operation.

  After the change of the direction of the movable mirror 17a is completed, the control circuit 120 resumes power supply to the drive line 35 of the shutter 16a and returns the shutter 16a to the open state (S604). As a result, a new optical connection from the input optical fiber 11 to the third output optical fiber 18 is established. The control circuit 120 reports the end of the switching operation to the host controller (S605), thereby completing the series of switching operations.

  As described above, according to this embodiment, in the optical switch that selectively switches the output optical fiber by changing the direction of the movable mirror, that is, by rotating, a shutter is provided near the movable mirror, and the change of the direction of the movable mirror is the most. During this, since the light beam directed toward the movable mirror is blocked by the shutter, crosstalk does not occur in the output optical fiber that is not related to the switch operation during the change of the direction of the movable mirror. That is, the occurrence of crosstalk during switching (switching of the output optical fiber) can be suppressed independently for each switching unit, that is, for each wavelength.

  Furthermore, according to the present embodiment, the shutter 16a is in a closed state when no drive signal is applied to the drive line 35. For example, even if light is input to the input optical fiber when the power is turned off, light is output from the output optical fiber. It is never output. Thereby, the malfunction of the apparatus is prevented and the ease of operation is increased.

  In the present embodiment, the shutter 16a can be realized with a simple structure, and both downsizing and cost reduction can be achieved.

  The front surface of the light shielding unit 31 (the surface on which the light beam is incident) is preferably low in reflectance. Furthermore, the front surface of the light shielding portion 31 is preferably non-regular reflection. For example, the front surface of the light shielding unit 31 may be a rough surface so as to diffuse the incident light beam. Alternatively, a grating that deflects the incident light beam in a specific direction may be formed on the front surface of the light shielding unit 31. This configuration has the effect of reducing unwanted stray light. That is, since the reflected light from the front surface of the light shielding unit 31 is scattered and hardly returned to the input optical fiber or the output optical fiber, the occurrence of crosstalk can be more effectively suppressed.

  The shutter is manufactured using, for example, MEMS technology, and in this case, the light shielding portion 31 is generally made of Si. In long-distance optical communication, infrared light (1.3 to 1.6 μm) is generally used. Infrared light undesirably penetrates Si to some extent. For this reason, it is preferable to further provide a metal film or the like on the back surface of the light shielding unit 31 in order to reliably block the light beam that is to pass through the light shielding unit 31.

  Further, as shown in FIG. 5A, in the closed state, the front surface of the light shielding portion 31 is movable substantially orthogonal to the rotation axis of the movable mirror 17a, particularly with respect to the principal ray of the light beam directed to the movable mirror 17a. It is preferable that the mirror 17a be inclined to some extent (for example, 1 degree or more) around an axis in a direction along the front surface. This configuration has the effect of reducing unwanted stray light. That is, since the light reflected by the front surface of the light shielding portion 31 is not incident on or coupled to any output optical fiber, crosstalk can be reliably suppressed.

  In the case of this embodiment, the distance between the movable mirror 17a and the shutter 16a is important. If the distance is too close, the two mechanically interfere with each other. If the distance is too long, the light beam having the wavelength to be switched cannot be sufficiently blocked (crosstalk suppression), or conversely, the light having a wavelength not to be switched. It affects the beam. In order to avoid these problems, the light shielding part of the shutter 16a needs to be arranged in a range where the light beams do not overlap as shown by arrows in FIG.

  As typical or easy-to-design values, the pitch of the mirror 23 is 0.5 mm, the beam diameter on the mirror 23 is 0.1 mm, and the NA (Numerical Aperture) of the light beam is 0, including the rotation angle of the mirror 23. Consider the case of 1. The distance between the edges of the light beam is 0.4 mm, and since the light beam spreads from here at NA = 0.1 (about 5.7 degrees on one side), the distance d from the mirror 23 to the light shielding portion 31 is d <0. 4/2 / tan 5.7 ° ≈2 mm, and it can be seen that the light-shielding portion 31 is preferably arranged at a position within 2 mm from the mirror 23. As a result, it is possible to reliably suppress the crosstalk for the object to be switched, and at the same time, to suppress the influence on other channels (such as light loss). In actual design, the pitch of the mirrors 23 is designed to be narrower due to restrictions on the manufacturing of the grating 15 (the groove pitch needs to be narrowed to widen the mirror interval, that is, the wavelength interval) and the movable mirror array 17 is downsized. In this case, the position of the shutter 16a needs to be closer to the movable mirror 17a.

  Further, as shown in FIGS. 4, 5A, and 5B, the beam portion 32 of the shutter 16a is located on the movable mirror 17a side from the light shielding portion 31, that is, the beam portion 32 is incident light on the movable mirror 17a. Since it extends to the opposite side of the beam, there is no member that protrudes closer to the convex lens 14 than the light-shielding portion 31, and the degree of freedom in optical design increases. For example, it becomes easy to design the convex lens 14 with a plurality of lenses, and as a result, optical characteristics are improved, and for example, insertion loss can be improved.

  5A and 5B, the light beam directed toward the movable mirror 17a is set so as to be incident on the approximate center of the movable mirror 17a. However, the incident position of the light beam may be offset from the approximate center of the movable mirror 17a. Good. In this specification, “substantially the center” means the center and the vicinity of the center. In general, in order to ensure the deflection angle of the movable mirror, it is advantageous to increase the driving force of the movable mirror. Therefore, the larger mirror portion is better. In this case, as shown in FIG. 8, the movable mirror is designed to be large, while the incident position of the light beam is offset from the center of the movable mirror (approached to the end). As a result, it is possible to avoid an increase in the size of the light-shielding portion and movable range of the shutter while increasing the driving force and ensuring the deflection angle of the movable mirror.

  Further, in the present embodiment, the shutter 16a is driven by electromagnetic driving that can generate a large driving force, so that an increase in switch time due to opening and closing of the shutter can be minimized. Further, since the driving force is large, it is possible to realize a large stroke of the light-shielding portion, thereby improving the degree of freedom in designing the peripheral portion of the movable mirror including the shutter.

  Of course, the driving method of the shutter 16a is not limited to electromagnetic driving, and various methods are conceivable. For example, driving with an electrostatic force similar to that of the movable mirror of this embodiment is also conceivable. In this case, the driving force is slightly reduced, but the shutter structure can be simplified or downsized.

  FIG. 13 is a perspective view of another shutter applicable to the optical switch 100 of the present embodiment. FIG. 14 is a side view of the shutter shown in FIG. As shown in FIGS. 13 and 14, the shutter 70 of this modification has an elastically deformable plate-like beam portion 72 that is cantilevered by a fixing portion 71. The beam portion 72 is supported substantially parallel to the principal ray of the light beam directed toward the movable mirror 17a. In this specification, “substantially parallel” means being exactly parallel and being nearly parallel. The beam portion 72 includes a light shielding portion 73 and a spring portion 74 connecting the light shielding portion 73 and the fixing portion 71. That is, the beam portion 72 has a light shielding portion 73 at its free end. The bending rigidity of the spring part 74 is smaller than the bending rigidity of the light shielding part 73, so that only the spring part 74 can be elastically bent and deformed substantially. With the bending deformation of the spring portion 74, the light shielding portion 73 moves in the vertical direction of FIG.

  The shutter 70 further includes a permanent magnet 79 disposed at a distance from the light shielding portion 73 and a drive coil 75 provided on the light shielding portion 73. The magnetic flux of the permanent magnet 79 and the current flowing through the drive coil 75 generate an electromagnetic force by interaction, and the light shielding portion 73 is moved by the generated electromagnetic force. That is, the permanent magnet 79 and the drive coil 75 constitute a drive unit that moves the light blocking unit 73 by bending and deforming the beam unit 72.

  The drive coil 75 is connected to an extraction electrode 77 formed on the fixed portion 71 via a wiring 76 extending through the spring portion 74, and can supply current from the outside. The permanent magnet 79 is polarized in the direction in which the light shielding portion 73 moves, and is arranged so that one end is on the light shielding portion 73 and the other end is on the fixing portion 71. Thereby, the electromagnetic force can be generated only in the portion of the drive coil 75 near the free end of the light shielding portion 73.

  As described above, in order to scatter the reflected light, carbon, TiN or the like is applied to the front surface of the light shielding portion 73 (the surface on which the light beam is incident, that is, the surface opposite to the surface on which the drive coil 75 is formed). A film may be formed. However, in the case of this shutter, the light shielding portion 73 enters at a small angle with respect to the incident light beam. In other words, the traveling direction of the specularly reflected light is significantly different from the traveling direction of the incident light beam. It is preferable to provide a regular reflection of light by providing a highly reflective metal film or the like on the surface. As a result, generation of undesired stray light that re-enters the input optical fiber 11 and the output optical fiber 18 can be more suitably suppressed. In other words, the front surface of the light-shielding portion 73 is preferably provided with regular reflection with respect to light. As a result, the reflection angle at the front surface of the light-shielding portion 73 is large, and the reflected light is not incident on or coupled to any output optical fiber, so that crosstalk can be reliably suppressed.

  Furthermore, as described above, the light shielding portion 73 is generally made of Si, and infrared light (1.3 to 1.6 μm) is generally used for long-distance optical communication. Infrared light undesirably penetrates Si to some extent. For this reason, a light shielding film 78 such as a metal film is formed on the surface of the light shielding film 78 on which the drive coil 75 is formed in order to reliably shield the light beam that is about to pass through the light shielding portion 31.

  The shutter of this modification can be manufactured based on a manufacturing method disclosed in, for example, Japanese Patent Laid-Open No. 10-20226.

  According to the shutter 70 of this modified example, as shown in FIG. 14, while the movable mirror 17a is switched, that is, while the direction of the movable mirror 17a is changed, the movable mirror 17a is supplied by supplying a drive current to the shutter. The light which goes to can be shielded, and crosstalk can be suppressed. In this modification, the structure of the shutter 70 can be simplified. Furthermore, the shutter 70 of the present modification can block the light beam by the movement of the relatively small light shielding portion 73, so that the degree of freedom in design is improved.

  FIG. 13 shows a configuration in which a light shielding state is taken when a current is supplied to the drive coil 75. However, the light shielding state is taken when a current is not supplied, and the light shielding portion 73 is a permanent magnet when the current is supplied. It may be changed so as to be attracted to 79 and take a non-light-shielding state. In this case, as already described in the first embodiment, it is possible to prevent malfunction of the apparatus and improve the ease of operation.

Second Embodiment The present embodiment is directed to another optical switch that switches wavelength-multiplexed signal light for each wavelength. FIG. 9 shows the configuration of the optical switch of the second embodiment of the present invention. In FIG. 9, members indicated by the same reference numerals as those shown in FIG. 1 are similar members, and detailed description thereof is omitted.

  As shown in FIG. 9, in the optical switch 200 of this embodiment, a fixed mirror 42 and a relay lens 43 are added as compared with the optical switch of the first embodiment shown in FIG. 1, and the movable mirror 17a is a shutter. It is arranged away from 16a.

  The shutter 16 a is disposed near the convergence point of the convergent light beam from the convex lens 14. The fixed mirror 42 deflects the light beam that has passed through the shutter 16 a toward the relay lens 43. The convergent light beam from the convex lens 14 passes through the shutter 16a and becomes a divergent light beam, and the relay lens 43 changes the divergent light beam into a convergent light beam. The movable mirror 17 a is disposed near the convergence point of the convergent light beam from the relay lens 43.

  The shutter 16 a and the movable mirror 17 a are disposed at a confocal position via the relay lens 43. For this reason, the optical switch 200 of this embodiment is optically equivalent to the optical switch 100 of the first embodiment. Therefore, the optical switch 200 of this embodiment operates in exactly the same manner as the optical switch 100 of the first embodiment.

  Compared to the optical switch 100 of the first embodiment, the optical switch 200 of the present embodiment is larger in overall size because the number of fixed mirrors and relay lenses is increased, but the positions of the movable mirror and the shutter are separated. Flexible design of movable mirrors and shutters. That is, in this embodiment, the movable mirror 17a in the optical switch of the first embodiment is moved to an optically equivalent position to improve the overall layout.

  When the movable mirror and the shutter are arranged in an optically equivalent position as in the present embodiment, the shutter is in a position that is completely confocal with the movable mirror, as described in the first embodiment. It is desirable to arrange at a position within 2 mm from the position.

  FIG. 10 shows a configuration of a shutter that can be suitably applied to the optical switch 200 of the present embodiment. As shown in FIG. 10, this shutter includes an elastically deformable beam portion 52 that is supported at both ends by a pair of fixing portions 53, and a flat light-shielding portion 51 that is supported substantially at the center of the beam portion 52. And have. The beam portion 52 extends along the front surface (the surface on which the light beam is incident) of the light shielding portion 51. The light-shielding portion 51 is driven in the vertical direction in the figure by an electrostatic force by a drive electrode (not shown) provided near the center of the beam portion 52. Details of this shutter are disclosed in, for example, Japanese Patent Laid-Open No. 2000-258704.

  In the case of this shutter, since it is possible to reduce the size in the depth direction (light traveling direction), the shutter portion can be configured more compactly.

  FIG. 11 shows another shutter configuration that can be suitably applied to the optical switch 200 of the present embodiment. As shown in FIG. 11, the shutter 60 of the present modification has an elastically deformable flat beam 61 that is cantilevered by a fixing portion 63, and the beam 61 has its free end. Has a light shielding portion 62. The shutter further includes a permanent magnet 64 disposed laterally from the beam portion 61, a drive line 65 provided on the beam portion 61, and a pad 66 for supplying a current to the drive line 65. doing. The permanent magnet 64 and the drive line 65 constitute a drive unit that moves the light shielding unit 62 by bending and deforming the beam unit 61.

  In this shutter, like the shutter shown in FIG. 3, the beam portion 61 is bent and deformed by the electromagnetic force caused by the interaction between the current flowing through the drive line 65 and the magnetic field formed by the permanent magnet 64. As a result, the light shielding portion 62 is moved.

  In the shutter 60 of this modification, it is possible to simplify the structure as well as downsizing. Further, since the size in the direction orthogonal to the light beam can be easily reduced, the degree of freedom in optical design is improved.

  The configuration of the shutter shown here can be applied not only to the optical switch of this embodiment but also to the optical switch shown in the first embodiment.

  In the first embodiment and the second embodiment, the optical switch having four output optical fibers has been described. However, the number of output optical fibers is not limited to this, and two, three, or five are provided. It may be more than this.

  In addition, the first embodiment and the second embodiment are 1: n demultiplexing optical switches having one input optical fiber and a plurality of output optical fibers. By reversing light, an n: 1 multiplexing optical switch may be used.

Third Embodiment The present embodiment is directed to a cross-connect type optical switch having a plurality of input optical fibers and a plurality of output optical fibers. FIG. 12 shows the configuration of the optical switch of the third embodiment of the present invention. In FIG. 12, members indicated by the same reference numerals as those shown in FIG. 1 are similar members, and detailed description thereof is omitted.

  As shown in FIGS. 3 and 4, the optical switch 300 of the present embodiment includes a plurality of input optical fibers 11, the same number of collimating lenses 112 as the input optical fibers 11, a plurality of output optical fibers 18, The same number of converging lenses 119 as the output optical fibers 18 are provided.

  Each of the collimating lenses 112 corresponds to the input optical fiber 11 and changes the divergent light beam emitted from the corresponding input optical fiber 11 into a parallel light beam. Each converging lens 119 corresponds to the output optical fiber 18 and converts the parallel light beam directed to the output optical fiber 18 into a convergent light beam.

  The optical switch 300 further includes a shutter array 116, an input side movable mirror array 117, and an output side movable mirror array 118.

  The shutter array 116 is located between the input optical fiber 11 and the collimating lens 112 and has the same number of shutters 116 a as the input optical fiber 11. Each of the shutters 116a corresponds to the input optical fiber 11, and appropriately blocks the light beam emitted from the corresponding input optical fiber 11. The shutter 116a may be composed of the various shutters described so far.

  The input side movable mirror array 117 has the same number of movable mirrors 117 a as the input optical fibers 11. Each of the movable mirrors 117a corresponds to the input optical fiber 11, and changes the direction of the light beam from the corresponding input optical fiber 11.

  The output side movable mirror array 118 has the same number of movable mirrors 118 a as the output optical fibers 18. Each of the movable mirrors 118a corresponds to the output optical fiber 18, and directs the light beam from the input side movable mirror array 117 to the corresponding output optical fiber 18.

  In the optical switch 300 of the present embodiment, the divergent light beam emitted from the input optical fiber 11 passes through the corresponding collimator lens 112 to become a parallel light beam, and enters the corresponding movable mirror 117a in the input side movable mirror array 117. To do. The movable mirror 117a directs the incident light beam to the corresponding movable mirror 118a in the output side movable mirror array 118 corresponding to the output optical fiber 18 to be output. The movable mirror 118 a directs the light beam from the input side movable mirror array 117 to the corresponding output optical fiber 18. The parallel light beam from the movable mirror 118 a passes through the corresponding converging lens 119 to become a converging light beam, and is incident on or coupled to the corresponding output optical fiber 18. Thereby, an optical connection is established.

  In the optical switch 300 of this embodiment, when the output destination of the light beam from the input optical fiber 11 is switched, the movable mirror 117a corresponding to the input optical fiber 11 and the movable mirror 118a corresponding to the output optical fiber 18 of the switching destination. And the direction is changed.

  At that time, as in the first embodiment, first, before starting the change of the orientation of the movable mirror 117a and the movable mirror 118a, the corresponding shutter 116a is closed, and the light traveling from the input optical fiber 11 to the movable mirror 117a. Cut off the beam. Subsequently, while the shutter 116a is maintained in the closed state, the directions of the movable mirror 117a and the movable mirror 118a are changed. Next, after the change of the directions of the movable mirror 117a and the movable mirror 118a is completed, the shutter 116a is switched to the open state, and the light beam is allowed to enter the movable mirror 117a from the input optical fiber 11.

  As a result, the light beam emitted from the input optical fiber 11 enters or is coupled to the new switching destination output optical fiber 18 via the movable mirror 117a and the movable mirror 118a corresponding to the new switching destination output optical fiber 18. To do. As a result, an optical connection is established.

  According to this embodiment, since the light beam directed to the movable mirror is blocked by the shutter while the direction of the movable mirror is changed, an undesired cross on the output optical fiber side is also obtained in the cross-connect type optical switch. The occurrence of talk can be suppressed.

  Details of the configuration and operation of the cross-connect optical switch are disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-174724.

  In the present embodiment, a so-called 3D-MEMS type optical switch as shown in FIG. 12 or Japanese Patent Application Laid-Open No. 2001-174724 has been described. However, various types of optical switches including a 2D-MEMS type optical switch are described. It is applicable to.

  Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the scope of the present invention. May be.

The structure of the optical switch of 1st embodiment of this invention is shown. 2 shows a movable mirror array used in the optical switch of FIG. 2 shows a shutter array used in the optical switch of FIG. FIG. 4 is a perspective view of the movable mirror array of FIG. 2 and the shutter array of FIG. 3. FIG. 5 shows a “closed state” of one shutter shown in FIG. 4. FIG. 5B shows the “open state” of the shutter shown in FIG. 5A. 2 shows a flowchart of a switching operation in the optical switch shown in FIG. FIG. 6 is a diagram for explaining a range in which the light shielding portion of the shutter shown in FIGS. 3, 4, 5A, and 5B can be arranged. 6 shows another shutter configuration applicable in place of the shutter shown in FIGS. 5A and 5B. The structure of the optical switch of 2nd embodiment of this invention is shown. 10 shows a shutter configuration that can be suitably applied to the optical switch shown in FIG. 9. 10 shows another shutter configuration that can be suitably applied to the optical switch shown in FIG. 9. The structure of the optical switch of 3rd embodiment of this invention is shown. It is a perspective view of another shutter applicable to the optical switch of the first embodiment of the present invention. FIG. 14 is a side view of the shutter shown in FIG. 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Input optical fiber, 12 ... Collimating lens, 13 ... Convex lens, 14 ... Convex lens, 15 ... Grating, 16 ... Shutter array, 16a ... Shutter, 17 ... Movable mirror array, 17a ... Movable mirror, 18 ... Output optical fiber, 19 DESCRIPTION OF SYMBOLS ... Converging lens, 21 ... Frame, 22 ... Hinge, 23 ... Mirror, 31 ... Light-shielding part, 32 ... Beam part, 33 ... Fixed part, 34 ... Permanent magnet, 35 ... Drive line, 36 ... Pad, 42 ... Fixed mirror, 43 ... Relay lens 51 ... Shading part 52 ... Beam part 53 ... Fixed part 60 ... Shutter 61 ... Beam part 62 ... Shading part 63 ... Fixed part 64 ... Permanent magnet 65 ... Driving line 66 DESCRIPTION OF SYMBOLS ... Pad, 70 ... Shutter, 71 ... Fixed part, 72 ... Beam part, 73 ... Light-shielding part, 74 ... Spring part, 75 ... Drive coil, 76 ... Wiring, 77 ... Lead electrode, 78 ... Light shielding 79 ... Permanent magnet, 100 ... Optical switch, 112 ... Collimating lens, 116 ... Shutter array, 116a ... Shutter, 117 ... Input side movable mirror array, 117a ... Movable mirror, 118 ... Output side movable mirror array, 118a ... Movable mirror DESCRIPTION OF SYMBOLS 119 ... Convergent lens, 120 ... Control circuit, 200 ... Optical switch, 300 ... Optical switch.

Claims (35)

At least one input optical fiber;
A plurality of output optical fibers;
At least one movable mirror for selectively directing a light beam from the input optical fiber to any one of the output optical fibers;
Having at least one shutter for appropriately blocking the light beam from the input optical fiber toward the movable mirror;
The direction of the movable mirror can be changed, and by changing the direction of the movable mirror, the output optical fiber to which the light beam reflected by the movable mirror is combined is switched,
The shutter is an optical switch that blocks a light beam directed to the movable mirror while the direction of the movable mirror is changed.   A light beam of wavelength-multiplexed light (light including a plurality of wavelength components) is emitted from the input optical fiber, and the optical switch converts the light beam from the input optical fiber into a plurality of light beams based on the wavelengths. And a lens for converting the split light beam into a convergent light beam, wherein the optical switch has a plurality of movable mirrors including the movable mirror, and the plurality of movable mirrors are spectrally separated. It corresponds to the plurality of light beams dispersed by the spectrometer in the same number as the plurality of light beams dispersed by the spectrometer, and the optical switch has a plurality of shutters including the shutter, The number of shutters is the same as that of the plurality of movable mirrors, and corresponds to the plurality of movable mirrors, and each of the shutters is disposed between the lens and the movable mirror. Blocking the light beam directed to the optical switch according to claim 1.   The shutter has an elastically deformable plate-like beam portion that is cantilevered, the beam portion has a light-shielding portion at its free end, and the shutter bends and deforms the beam portion. The optical switch according to claim 2, further comprising a drive unit that moves the light shielding unit.   The optical switch according to claim 3, wherein the beam portion is supported substantially parallel to a principal ray of a light beam directed toward the movable mirror.   The optical switch according to claim 4, wherein the driving unit deforms the beam unit by electromagnetic force.   The optical switch according to claim 4, wherein a front surface of the light shielding portion (a surface on which a light beam is incident) has regular reflectivity with respect to light. The optical switch according to claim 4, wherein the shutter blocks a light beam directed to the movable mirror at a position within about 2 mm from the movable mirror.   The optical switch according to claim 4, wherein the shutter blocks a light beam directed toward the movable mirror at a position optically confocal with the movable mirror.   The optical switch according to claim 3, wherein the beam portion is supported substantially perpendicularly to a principal ray of a light beam directed toward the movable mirror.   The optical switch according to claim 9, wherein a front surface of the light shielding portion (a surface on which the light beam is incident) has non-regularity with respect to light.   The optical switch according to claim 3, wherein the shutter is driven in accordance with a driving electric signal, and blocks a light beam directed to the movable mirror in a state where the driving electric signal is not supplied.   The shutter includes an elastically deformable beam part that is cantilevered and a flat light shielding part joined to a free end of the beam part, and the light shielding part is substantially in contact with the beam part. The optical switch according to claim 2, further comprising a drive unit that extends vertically and further moves the light shielding unit by bending and deforming the beam unit.   The optical switch according to claim 12, wherein the beam portion is located closer to the movable mirror than the light shielding portion.   In a state where the shutter blocks the light beam directed toward the movable mirror, the light shielding portion is substantially orthogonal to the rotation axis of the movable mirror with respect to the principal ray of the light beam directed toward the movable mirror. The optical switch according to claim 12, wherein the optical switch is inclined at least 1 degree around an axis in a direction along the front surface.   The optical switch according to claim 12, wherein the driving unit deforms the beam unit by electromagnetic force.   13. The movable mirror according to claim 12, wherein the movable mirror has a longer dimension with respect to the moving direction of the light shielding portion of the shutter than the light shielding portion, and the light beam directed toward the movable mirror is incident on a position offset from the center of the movable mirror. Light switch.   The optical switch according to claim 12, wherein the shutter is driven according to a driving electric signal, and blocks a light beam directed to the movable mirror in a state where the driving electric signal is not supplied.   The shutter includes an elastically deformable beam portion supported by both ends and a flat light shielding portion supported substantially at the center of the beam portion, and the beam portion is a front surface of the light shielding portion. 3. A driving portion that extends along a surface (a surface on which a light beam is incident) and further deforms the beam portion to move the light shielding portion along the front surface. The optical switch as described in.   The optical switch has a plurality of input optical fibers including the input optical fiber and at least one movable mirror array, and each movable mirror array has the same number of movable mirrors as the plurality of input optical fibers, The optical switch according to claim 1, wherein the plurality of movable mirrors of each movable mirror array respectively correspond to a plurality of light beams from a plurality of input optical fibers.   The shutter has an elastically deformable plate-like beam portion that is cantilevered, the beam portion has a light-shielding portion at its free end, and the shutter bends and deforms the beam portion. The optical switch according to claim 19, further comprising a drive unit that moves the light shielding unit.   21. The optical switch according to claim 20, wherein the beam portion is supported substantially parallel to a principal ray of a light beam directed toward the movable mirror.   The optical switch according to claim 21, wherein the driving unit deforms the beam unit by electromagnetic force.   The optical switch according to claim 21, wherein a front surface (a surface on which a light beam is incident) of the light shielding portion has a regular reflection property with respect to light.   The optical switch according to claim 21, wherein the shutter blocks a light beam directed toward the movable mirror at a position optically confocal with the movable mirror.   21. The optical switch according to claim 20, wherein the beam portion is supported substantially perpendicularly to a principal ray of a light beam directed toward the movable mirror.   26. The optical switch according to claim 25, wherein a front surface of the light shielding portion (a surface on which a light beam is incident) has non-regular reflection with respect to light.   21. The optical switch according to claim 20, wherein the shutter is driven according to a driving electric signal, and blocks a light beam directed to the movable mirror in a state where the driving electric signal is not supplied.   The shutter includes an elastically deformable beam part that is cantilevered and a flat light shielding part joined to a free end of the beam part, and the light shielding part is substantially in contact with the beam part. The optical switch according to claim 19, further comprising a drive unit that extends vertically and further moves the light shielding unit by bending and deforming the beam unit.   The optical switch according to claim 28, wherein the beam portion is located closer to the movable mirror than the light shielding portion.   In a state where the shutter blocks the light beam directed toward the movable mirror, the light shielding portion is substantially orthogonal to the rotation axis of the movable mirror with respect to the principal ray of the light beam directed toward the movable mirror. 29. The optical switch according to claim 28, wherein the optical switch is inclined at least one degree around an axis in a direction along the front surface.   29. The optical switch according to claim 28, wherein the drive unit deforms the beam unit by electromagnetic force.   29. The movable mirror according to claim 28, wherein the movable mirror has a longer dimension with respect to the moving direction of the light shielding portion of the shutter than the light shielding portion, and the light beam directed toward the movable mirror is incident on a position offset from the center of the movable mirror. Light switch.   29. The optical switch according to claim 28, wherein the shutter is driven according to a driving electric signal, and blocks a light beam directed to the movable mirror in a state where the driving electric signal is not supplied.   The shutter includes an elastically deformable beam portion supported by both ends and a flat light shielding portion supported substantially at the center of the beam portion, and the beam portion is a front surface of the light shielding portion. 20. A driving portion that extends along a surface (a surface on which a light beam is incident) and further deforms the beam portion to move the light shielding portion along the front surface. The optical switch as described in. At least one input optical fiber, a plurality of output optical fibers, at least one movable mirror for selectively directing a light beam from the input optical fiber to any one of the output optical fibers, and An optical switch control method comprising at least one shutter for appropriately blocking a light beam directed from the input optical fiber toward the movable mirror,
Before starting to change the orientation of the movable mirror, the shutter is closed to block the light beam toward the movable mirror;
Changing the direction of the movable mirror while the shutter is closed;
And a step of opening the shutter after the change of the direction of the movable mirror is completed to allow the light beam to be incident on the movable mirror.

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