JP4495095B2 - Micromirror device and mirror array - Google Patents

Description

  The present invention relates to a micromirror device and a mirror array used for optical switching elements for communication, measuring instruments, displays, scanners, wavelength selective switches, and the like.

  In the field of optical networks, which are the foundation of Internet communication networks, optical MEMS (Micro Electro Mechanical System) technology is in the spotlight as a technology that realizes multi-channel, wavelength division multiplexing (WDM), and cost reduction. An optical switch has been developed using this technique (see, for example, Patent Document 1). The most characteristic component of this MEMS type optical switch is a micromirror device. The optical switch enables path switching without converting light into an electrical signal and without demultiplexing multiplexed light for each wavelength. Such an optical switch is used to maintain a state where signals can be distributed to another route when a failure occurs in the route being used, and communication is possible.

  On the other hand, in recent years, a wavelength selective switch that demultiplexes multiplexed light for each wavelength and individually selects a light path of each wavelength has been researched and developed (for example, see Patent Document 2). A micromirror device is also used for this wavelength selective switch. FIG. 8 is a block diagram showing the configuration of the wavelength selective switch disclosed in Patent Document 2. In FIG. A wavelength multiplexed signal obtained by multiplexing optical signals having different wavelengths λ1 to λ5 is input to the wavelength multiplexed signal input port 50 of the wavelength selective switch. An optical signal demultiplexer 51 composed of a grating or the like demultiplexes the wavelength multiplexed signal for each wavelength and inputs the demultiplexed signals to the input ports 52 to 56. 1-input 4-output optical switches 57-61 provided corresponding to the input ports 52-56 are multi-stages of 1-input 2-output optical switches 70-72, 73-75, 76-78, 79-81, 82-84, respectively. It is the structure connected to. The four output lines of the 1-input 4-output optical switch 57 are connected to 5-input optical signal multiplexers 62-65 corresponding to the output ports 66-69, respectively. Similarly, each of the four output lines of the 1-input 4-output optical switches 58 to 61 is connected to the 5-input optical signal multiplexers 62 to 65, respectively. The five-input optical signal multiplexers 62 to 65 couple the input optical signals to the output ports 66 to 69, respectively.

  Here, as a specific switching example, a case will be described in which an optical signal having a wavelength λ1 among the wavelength multiplexed signals input to the wavelength multiplexed signal input port 50 is output to the output port 68. The optical signal having the wavelength λ1 is demultiplexed by the optical signal demultiplexer 51 and input to the 1-input 4-output optical switch 57. The 1-input 2-output optical switch 70 in the first stage of the 1-input 4-output optical switch 57 is set so that the output on the 1-input 2-output optical switch 72 side is selected, and the 2-stage 1-input 2-output optical switch 72 is selected. Is set so that the output on the 5-input optical signal multiplexer 64 side is selected. As a result, the optical signal input from the input port 52 is sent to the 5-input optical signal multiplexer 64 via the 1-input 2-output optical switches 70, 72. The 5-input optical signal multiplexer 64 combines the optical signals from the other input ports and outputs them to the output port 68. In this way, the light path of each wavelength can be selected.

In the wavelength selective switch as described above, a micromirror device can be used as a component of the 1-input 2-output optical switches 70-84. An example of a conventional micromirror device described in Patent Document 1 is shown in FIGS. FIG. 9 is an exploded perspective view showing a configuration of a conventional micromirror device, and FIG. 10 is a cross-sectional view of the micromirror device of FIG.
The micromirror device 100 has a structure in which a mirror substrate 200 on which a mirror is formed and an electrode substrate 300 on which an electrode is formed are arranged in parallel.

  The mirror substrate 200 has a plate-like frame portion 210 having a substantially circular opening in a plan view and a substantially circular opening in a plan view, and is disposed in the opening of the frame portion 210 by a pair of movable frame connecting portions 211a and 211b. The movable frame 220 and a mirror 230 having a substantially circular shape in plan view disposed in the opening of the movable frame 220 by a pair of mirror connecting portions 221a and 221b. The frame part 210, the movable frame connecting parts 211a and 211b, the movable frame 220, the mirror connecting parts 221a and 221b, and the mirror 230 are integrally formed of, for example, single crystal silicon. A frame-shaped member 240 is formed on the upper surface of the frame portion 210 so as to surround the movable frame 220 and the mirror 230.

The pair of movable frame connecting portions 211a and 211b are each formed of a torsion spring, and connect the frame portion 210 and the movable frame 220. The movable frame 220 can rotate about the movable frame rotation axis x of FIG. 9 that passes through the pair of movable frame coupling portions 211a and 211b.
Similarly, the pair of mirror connecting portions 221a and 221b are each formed of a torsion spring, and connect the movable frame 220 and the mirror 230. The mirror 230 can rotate about the mirror rotation axis y of FIG. 9 passing through the pair of mirror connecting portions 221a and 221b. The movable frame rotation axis x and the mirror rotation axis y are orthogonal to each other. As a result, the mirror 230 rotates about two orthogonal axes.

  The electrode substrate 300 includes a plate-like base portion 310 and a terrace-like protrusion portion 320 that protrudes from the surface (upper surface) of the base portion 310 and is formed at a position facing the mirror 230 of the opposing mirror substrate 200. The base 310 and the protrusion 320 are made of, for example, single crystal silicon. The protrusion 320 includes a second terrace 322 having a truncated pyramid shape formed on the upper surface of the base 310, a first terrace 321 having a truncated pyramid shape formed on the upper surface of the second terrace 322, and the first terrace 321. It is composed of a pivot 330 having a columnar shape formed on the upper surface of one terrace 321. The pivot 330 is formed so as to be positioned approximately at the center of the first terrace 321. Accordingly, the pivot 330 is disposed at a position facing the center of the mirror 230.

  Four electrodes 340 a to 340 d are formed in circles concentric with the mirror 230 of the opposing mirror substrate 200 at the four corners of the protrusion 320 and the upper surface of the base 310 following the four corners. In addition, a pair of convex portions 360 a and 360 b arranged side by side so as to sandwich the protruding portion 320 is formed on the upper surface of the base portion 310. Furthermore, wirings 370 are respectively formed at locations between the protrusions 320 on the upper surface of the base 310 and the protrusions 360a and 360b. The wirings 370 are connected to electrodes via lead lines 341a to 341d. 340a to 340d are connected.

The mirror substrate 200 and the electrode substrate 300 as described above are arranged such that the lower surface of the frame portion 210 and the upper surfaces of the convex portions 360a and 360b are arranged so that the mirror 230 and the electrodes 340a to 340d corresponding to the mirror 230 are opposed to each other. Are joined together to form a micromirror device 100 as shown in FIG. In the micromirror device 100, the mirror 230 is grounded, a positive or negative voltage is applied to the electrodes 340a to 340d, and an asymmetric potential difference is generated between the electrodes 340a to 340d. The mirror 230 can be rotated in any direction by suction.
When the one-input / two-output optical switches 70 to 84 are configured using the micromirror device 100 as described above, the mirror 230 is irradiated with the optical signal from the input port, and the reflected light of the mirror 230 is transmitted to the two output ports. The tilt angle of the mirror 230 may be controlled so as to enter one of them.

JP 2003-57575 A Japanese Patent No. 3444548

  In the conventional micromirror device 100 shown in FIGS. 9 and 10, the connection point between the mirror 230 and the springs 221a and 221b is used as a substantially fixed point, and two or more such fixed points are provided. The mirror 230 was rotated using the axis connecting the points as the mirror rotation axis y. In the micromirror device 100 having such a configuration, it is necessary to separate the individual mirrors 230 by an amount corresponding to the size of the springs 221a and 221b forming the rotation shaft.

  However, in order to switch the path of light of each wavelength demultiplexed by a grating or the like like a wavelength selective switch, it is necessary to narrow the interval between individual mirrors to a certain value or less. If the distance between the mirrors becomes larger than the path distance of the demultiplexed light of each wavelength, light strikes between the mirrors, and a phenomenon that the light of that wavelength cannot be guided to the output port occurs. In order to switch an optical signal having a relatively dense wavelength interval demultiplexed by the grating using the wavelength selective switch, when the mirror width is set to 160 μm or more, for example, the mirror interval must be set to 40 μm or less. 9. The conventional micromirror device 100 shown in FIG. 10 has a problem that it cannot satisfy such a narrow mirror interval requirement.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a micromirror device and a mirror array in which a plurality of mirrors can be arranged close to each other.

The present invention relates to a mirror having a substantially rectangular shape in plan view, at least two extendable supports for rotatably supporting the mirror, and an inclination angle of the mirror formed on a lower substrate facing the mirror. And a support structure formed on the lower substrate on both sides in the length direction of the mirror, wherein the at least two supports are the longer one of the mirrors. Each end of the support is connected to an end in the length direction of the mirror, and the other end is the length of the support structure. A folded portion that is connected to an end portion in the direction and that folds back multiple times at a constant pitch in a direction orthogonal to the length direction, and is perpendicular to an axis along the length direction and parallel to the mirror surface The mirror is located with the axis as the first pivot axis. And the spring constant of the support is set so that the mirror can be rotated to a desired angle with the axis along the length direction as a second rotation axis. It is characterized by this.
In addition, one configuration example of the micromirror device of the present invention further includes a fulcrum projection made of a conductor in contact with the back surface of the mirror on the lower substrate just below the center of the mirror.
In addition, one configuration example of the micromirror device of the present invention includes at least two or more drive electrodes.
Further, one configuration example of the micromirror device of the present invention includes at least three or more drive electrodes.
In addition, one configuration example of the micromirror device of the present invention further includes a power source that independently controls drive voltages applied to the plurality of drive electrodes.
The mirror array of the present invention is characterized in that a plurality of micromirror devices are arranged along a width direction perpendicular to the length direction.

  According to the present invention, at least two supports support both ends of the mirror in the length direction, and the first axis is perpendicular to the axis along the length direction and parallel to the mirror surface. The spring constant of the support is such that the mirror can be rotated to a desired angle as the rotation axis, and the mirror can be rotated to the desired angle with the axis along the length direction as the second rotation axis. By setting, the mirror can be rotated not only about the second rotation axis corresponding to the rotation axis of the conventional micromirror device but also about the first rotation axis, The need to place a support in the gap between each mirror can be eliminated. As a result, in the present invention, a plurality of micromirror devices can be arranged close to each other along the width direction perpendicular to the length direction, and the micromirror device is applied to an element such as a wavelength selective switch having a small mirror interval. can do.

  Further, according to the present invention, by providing a fulcrum protrusion in contact with the back surface of the mirror on the lower substrate immediately below the center of the mirror, it is possible to prevent the mirror from sinking to the drive electrode side. Moreover, the height of the rotation axis | shaft of a mirror can be prescribed | regulated by preventing sinking of a mirror. That is, the mirror exists on the rotation axis, so that the optical design can be facilitated and the deviation from the design can be reduced. If there is no mirror on the rotation axis, the distance between the mirror and other optical elements changes depending on the amount of rotation of the mirror, and the optical system that takes this change in distance into account or an optical that corrects the change in distance A system design is required, and a burden is imposed on the design. In the present invention, such a burden can be reduced.

  In the present invention, by providing at least two or more drive electrodes, the mirror can be rotated around the first rotation axis by the electrostatic force generated between the drive electrodes and the mirror. As a result, when the micromirror device of the present invention is applied to a wavelength selective switch, an optical signal demultiplexed by a grating can be reflected by a mirror and guided to a desired output port.

  In the present invention, by providing at least three or more drive electrodes, the mirror is moved around the first rotation axis and the second rotation axis by the electrostatic force generated between the drive electrode and the mirror. Can be rotated. As a result, when the micromirror device of the present invention is applied to a wavelength selective switch, the mirror is moved to the second position when the optical signal demultiplexed by the grating is reflected by the mirror and guided to a desired output port. By rotating the optical signal around the axis and once deflecting the optical signal from the output port, it is possible to prevent the optical signal from being applied to ports other than the original output port.

  Further, in the present invention, by providing a power source for independently controlling the drive voltages applied to the plurality of drive electrodes, the tilt angle around the first rotation axis and the tilt angle around the second rotation axis of the mirror are provided. And can be controlled independently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A is a plan view showing a configuration of a micromirror device according to an embodiment of the present invention, FIG. 1B is a perspective view of the micromirror device of FIG. 1A, and FIG. 2A is a sectional view taken along line II-II in FIG. 1A. FIG.

  The micromirror device 1 according to the present embodiment uses an electrostatic force generated by a parallel plate electrode structure as a drive source, and has a plate-like mirror 2 having a substantially rectangular shape in plan view and a lower substrate 7 facing the mirror 2. The drive electrode 3a, 3b, 3c, 3d formed on the upper side and one end connected to the mirror 2 and the other end connected to the support structure 8a, 8b formed on the lower substrate 7 are rotated. Springs 4a and 4b which are support bodies that can be supported, wirings 5a, 5b, 5c and 5d which are formed on the lower substrate 7 and supply driving voltages to the driving electrodes 3a, 3b, 3c and 3d, respectively, and the lower substrate 7 includes a pivot 6, a lower substrate 7, and support structures 8a and 8b. In FIGS. 1A and 1B, the lower substrate 7 and the support structures 8a and 8b are not shown. In FIG. 1A, the wirings 5a, 5b, 5c, 5d are provided on the surface of the lower substrate 7, but the wirings 5a, 5b, 5c, 5d may be embedded in the lower substrate 7. Good.

  In the example of FIGS. 1A and 1B, the mirrors 2 are arranged at substantially constant intervals. However, when the frequency selection of the optical signals for selecting the path by the wavelength selection switch is designed to be constant, the interval between the mirrors 2 is not constant, and the interval between the mirrors 2 is related to the frequency of the optical signal. The interval may be calculated by. On the other hand, when the wavelength selection switch is designed so that the wavelength interval of each optical signal for selecting a path is constant, the interval between the mirrors 2 is generally constant. In any case, whether or not the distance between the mirrors 2 is constant is determined by the arrangement of the mirrors 2, the functions of other optical elements, and the relative positional relationship.

  The width MW of the mirror 2, the pitch MP of the mirror 2, the length ML of the mirror 2, etc. shown in FIG. 3 are the wavelength interval of each optical signal for selecting the path by the wavelength selection switch, the pass band or transmission band of the optical signal, the light It is determined by the specifications and design of the signal beam. For example, the width MW of the mirror 2 is 160 μm, the length ML is 400 μm, and the pitch MP is 200 μm. At this time, if the wavelength interval of the optical signal is ideally 100 GHz, the pass band is 80 GHz.

  Although the operation specifications of the mirror 2 also differ depending on the element design, in the present embodiment, an axis perpendicular to the axis connecting the two connection points of the mirror 2 and the springs 4a and 4b and parallel to the mirror surface (FIG. 1). (A) The axis connecting the two connection points of the mirror 2 and the springs 4a and 4b with the rotation of the mirror 2 having the axis A) of FIG. The object is to manufacture a mirror 2 that can also be rotated finely, with 1 (A) and the axis B) of FIG. 1 (B) as the second rotation axis.

  In the conventional micromirror device shown in FIGS. 9 and 10, the connection point between the mirror 230 and the spring is a substantially fixed point, and two or more such substantially fixed points are provided, and an axis connecting the two substantially fixed points. Is rotated about the rotation axis (mirror rotation axis y in FIG. 9). However, as described above, in the wavelength selective switch, it is necessary to arrange a plurality of mirrors close to each other, and a support such as a spring cannot be arranged in the gap between the mirrors.

  Therefore, in the present embodiment, the springs 4a and 4b are arranged not in the main first rotation axis A but in the direction along the secondary second rotation axis B, so that the mirror 2 and the springs 4a and 4b are arranged. By operating the connection point as a movable point instead of a substantially fixed point, the need to place a support in the gap between each mirror was eliminated. By adopting such a structure, the mirror 2 can be rotated around the rotation axis A, and a plurality of micromirror devices 1 can be arranged close to each other. The micromirror device 1 can be applied to an element such as a switch.

  The mirror 2 and the springs 4a and 4b are integrally formed of single crystal silicon, and a ground potential is applied to the mirror 2 via the springs 4a and 4b. Then, a positive or negative drive voltage is applied to the drive electrodes 3a, 3b, 3c, 3d from the power source (not shown) via the wires 5a, 5b, 5C, 5d, and the drive electrodes 3a, 3b, 3c, 3d are asymmetrical. By generating a large potential difference, the mirror 2 can be attracted by electrostatic attraction, and the mirror 2 can be rotated in any direction around the first rotation axis A or around the second rotation axis B. . A metal such as gold or aluminum is deposited on the upper surface of the mirror 2 made of silicon in order to improve the reflectance of infrared rays. Similarly, a metal such as gold or aluminum is deposited on the lower surface of the mirror 2.

  However, in the present embodiment, unlike the micromirror device shown in FIGS. 9 and 10, the connection point between the mirror 2 and the springs 4a and 4b needs to be movable in the z-axis direction. That is, when a drive voltage is applied to the drive electrodes 3a, 3b, 3c, 3d, the connection point between the mirror 2 and the springs 4a, 4b must be easily moved to the drive electrode side or the opposite side of the drive electrode. . For this purpose, springs 4a and 4b having spring constants capable of realizing a desired rotation angle are produced when an electrostatic force corresponding to the area of the drive electrodes 3a, 3b, 3c, and 3d and the drive voltage is generated.

  In the conventional design of the spring, it was designed to prevent the mirror from sinking in the direction perpendicular to the mirror surface, but in this embodiment, the spring 4a, 4b toward the drive electrode (−z direction). It is important to realize a desired rotation angle of the mirror 2 while controlling the sinking of the mirror 2. Therefore, the spring constant which is important when designing the operation of the mirror 2 around the first rotation axis A is parallel to the axis passing through two connection points of the mirror 2 and the springs 4a and 4b, and the mirror. 2 parallel to the plane (yz plane in FIGS. 1A and 1B) (2 along the y and z axes in FIGS. 1A and 1B). Direction) spring constant. Further, as a spring constant that is important when designing the operation of the mirror 2 around the second rotation axis B, there is a spring constant around the rotation axis B.

  The spring constants in the y and z axis directions and the spring constant around the rotation axis B are determined by the size of the drive electrodes 3a, 3b, 3c, and 3d, the size of the drive voltage, the area of the mirror 2, and the like. The spring constant in the x-axis direction is determined in consideration of the problem of contact between mirrors, the problem of displacement of the mirror 2 during operation, and the problem of yield during manufacturing.

  The structural parameters of the springs 4a and 4b are shown in FIG. 4, and the structural parameters of the electrodes 3a, 3b, 3c and 3d are shown in FIG. In FIG. 4, SL is the spring length, STL is the length of the folded portion, SP is the spring pitch, SHP is the spring half pitch, SW is the spring width, and SIL is the distance from the folded portion to the mirror 2. , SOL is the spring outer connection length which is the distance from the folded portion to the support structures 8a, 8b, and n is the number of folded. In FIG. 5, EL is the electrode length, EW is the electrode width, ELD is the distance between the electrodes in the length direction, EWD is the distance between the electrodes in the width direction, PED is the distance between the pivots and the electrodes, and PD is the pivot diameter.

  In order to rotate the mirror 2 around the rotation axis A, it is necessary to divide the drive electrode into a set of 3a, 3b and a set of 3c, 3d. Further, in order to rotate the mirror 2 around the rotation axis B, it is necessary that the drive electrode can be further divided into left and right and the drive voltage can be controlled independently. Therefore, in the present embodiment, the drive electrode has a four-divided configuration of 3a, 3b, 3c, and 3d. However, the minimum number of drive electrodes required to rotate the mirror 2 around the rotation axes A and B is three. The reason that the minimum number of drive electrodes is three is that the rotation of the mirror 2 around the B axis can achieve its purpose only in one direction, not in both directions.

  If the springs 4a and 4b are designed so that the connection point between the mirror 2 and the springs 4a and 4b can easily move in the z-axis direction, the mirror 2 to be realized when a drive voltage is applied to the drive electrodes 3a, 3b, 3c and 3d. The entire mirror may be attracted to the drive electrode side without being able to achieve or control the angle. In order to prevent such attraction, in this embodiment, a pivot 6 serving as a fulcrum protrusion is formed on the lower substrate 7 immediately below the center of the mirror 2. The pivot 6 is made of a conductor such as silicon or gold, and is set to be equal to the surface potential of the electrode facing surface (lower surface) of the mirror 2. This potential setting is for preventing the mirror 2 and the pivot 6 from sticking to each other. The pivot 6 prevents the center of the mirror 2 from being attracted to the drive electrode side. As a result, the mirror 2 rotates around the rotation axes A and B. Since the mirror 2 can be rotated with the upper portion of the pivot 6 as a reference position, the position of the mirror center in the Z direction is not displaced while the mirror 2 is rotating. The pivot 6 can accurately determine the height of the rotation axis of the mirror 2. As a result, the amount of deviation from the optical design can be reduced.

  A drive voltage is applied to one of the pair of drive electrodes 3a and 3b and the pair of 3c and 3d, or a drive voltage of a different magnitude is applied to both sets, and mirrors as shown in FIG. When rotating 2 around the rotation axis A, the pivot 6 applies a force in the + z direction so that the mirror 2 does not sink. The spring 4a closer to the drive electrode side of the springs 4a and 4b by the rotation of the mirror 2 shown in FIG. 6 raises the end of the mirror 2 in the + z direction, and the spring 4b farther from the drive electrode side. Pulls down the end of the mirror 2 in the -z direction. On the other hand, the electrostatic force generated between the mirror 2 and the drive electrodes 3a, 3b, 3c, and 3d acts to attract the mirror 2 in the −z direction. Schematically, the mirror 2 stops at a certain angle by the balance between the electrostatic force, the restoring force of the springs 4a and 4b in the y and z directions, and the force of the pivot 6.

  Depending on the specification and design of the mirror 2, the pivot 6 may be omitted. When there is no pivot 6, when the mirror 2 rotates around the rotation axis A, the springs 4a and 4b both act to pull up the end of the mirror 2 in the + z direction. The mirror 2 stops when the electrostatic force and the restoring force of the springs 4a and 4b balance. When the pivot 6 is not provided, the mirror 2 is rotated by applying a driving voltage to one of the pair of driving electrodes 3a and 3b and the pair of 3c and 3d, and the distance between the spring and the driving electrode is determined by the spring. The inclination angle of the mirror 2 is determined by the difference between 4a and 4b. Although potentials may be applied to the four drive electrodes, the amount of sinking of the mirror 2 is increased, which is not a good idea. Since the mirror 2 is drawn to the drive electrode side as a whole, the position of the rotation axes A and B in the z-axis direction varies depending on the magnitude of the drive voltage. If the control is performed including the sinking characteristics of the rotation axes A and B, it is not necessary to use the pivot 6.

  In order to increase the tilt angle of the mirror 2, it is effective to increase the length ML of the mirror 2. The inclination angle of the mirror 2 is determined by the torque obtained by multiplying the electrostatic force and the distance from the rotating shaft. By increasing the distance from the rotation axis, the mirror 2 can be rotated with a small electrostatic force generated by the electrodes 3a, 3b, 3c and 3d as a large torque.

  However, if the length ML of the mirror 2 is large, the amount of displacement at the end of the mirror 2 increases when the mirror 2 rotates, and the lower substrate 7 and the electrodes 3a, 3b, 3c, 3d collide with the mirror 2. In order to prevent such a collision, it is necessary to increase the gap between the electrodes 3a, 3b, 3c, 3d and the mirror 2. Therefore, it is necessary to design the electrode 3a, 3b, 3c, 3d or the mirror 2 in consideration of an increase in driving force due to an increase in area and a decrease in driving force due to an increase in gap.

  When the mirror 2 is rotated around the rotation axis B, different driving voltages may be applied to the set of drive electrodes 3a and 3d and the set of 3b and 3c. In this case, the electrostatic force differs between the left and right sides of the mirror 2, and as a result, the mirror 2 rotates according to the difference in electrostatic force. The mirror 2 stops when the electrostatic force, the restoring force around the rotation axis B of the springs 4a and 4b, and the force of the pivot 6 are balanced.

  Next, the operation when the micromirror device 1 of the present embodiment is applied to a wavelength selective switch will be described with reference to FIG. First, incident light (optical signals) L1, L2, and L3 parallel to, for example, the yz plane are incident on the mirror 2 of each micromirror device 1 from an input port (not shown). Each mirror 2 reflects incident light L1, L2, L3 in the + y direction. At this time, since a plurality of output ports (not shown) are arranged along the y-axis in the + y direction, the reflected lights L4, L5, and L6 are reflected by adjusting the inclination angle around the rotation axis A of each mirror 2. Each can enter the desired output port.

  By the way, since the incident lights L1, L2, and L3 are always output from the input port, the rotation axis A is maintained with the angle around the rotation axis B of the mirror 2 fixed to switch the path of the optical signal. If the surrounding angle is changed, the optical signal may enter a port other than the original output port before the mirror 2 reaches a desired angle. Such an output error causes signal crosstalk.

  Therefore, when switching the path of the optical signal, the mirror 2 is first rotated around the rotation axis B, and the reflected light is tilted from the yz plane in the + x direction or the −x direction to deflect from the output port, and then the mirror. 2 is rotated around the rotation axis A to adjust the position of the reflected light in the y-axis direction, and then the mirror 2 is rotated around the rotation axis B to return the reflected light onto the output port. By doing so, it is possible to output an optical signal to a desired output port. This is the reason why minute rotation around the rotation axis B is necessary. By slightly rotating the mirror 2 around the rotation axis B, it is possible to prevent an optical signal from accidentally entering another output port when selecting an optical signal path, and to reduce signal crosstalk. It becomes possible.

  The present invention can be applied to, for example, a wavelength selective switch.

It is the top view and perspective view which show the structure of the micromirror device which concerns on embodiment of this invention. It is sectional drawing of the micromirror device of FIG. It is a figure for demonstrating the structural parameter of the mirror of the micromirror device of FIG. It is a figure for demonstrating the structural parameter of the spring of the micromirror device of FIG. It is a figure for demonstrating the structural parameter of the electrode of the micromirror device of FIG. It is a figure for demonstrating rotation of the mirror in the micromirror device of FIG. It is a figure for demonstrating operation | movement at the time of applying the micromirror apparatus of FIG. 1 to a wavelength selection switch. It is a block diagram which shows the structure of a wavelength selective switch. It is a disassembled perspective view which shows the structure of the conventional micromirror device. It is sectional drawing of the micromirror device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Micromirror apparatus, 2 ... Mirror, 3a, 3b, 3c, 3d ... Drive electrode, 4a, 4b ... Spring, 5a, 5b, 5c, 5d ... Wiring, 6 ... Pivot, 7 ... Lower substrate, 8a, 8b ... Support structure.

Claims (6)

A mirror that is substantially rectangular in plan view, at least two extendable supports that rotatably support the mirror, and a drive that controls the tilt angle of the mirror formed on the lower substrate facing the mirror A micromirror device comprising an electrode and a support structure formed on the lower substrate on both sides in the length direction of the mirror,
The at least two supports support both ends in the length direction along the longer two sides of the mirror, and each of the supports has one end at the end in the length direction of the mirror. Connected, the other end is connected to the end in the length direction of the support structure, and has a folded portion that folds back multiple times at a constant pitch in a direction perpendicular to the length direction,
The mirror can be rotated at a desired angle with an axis perpendicular to the axis along the length direction and parallel to the mirror surface as a first rotation axis, and along the length direction. A micromirror device characterized in that a spring constant of the support is set so that the mirror can be rotated to a desired angle with an axis as a second rotation axis. The micromirror device according to claim 1, wherein
Furthermore, a fulcrum protrusion made of a conductor in contact with the back surface of the mirror is provided on the lower substrate directly below the center of the mirror. The micromirror device according to claim 1 or 2,
A micromirror device comprising at least two or more of the drive electrodes. The micromirror device according to claim 1 or 2,
A micromirror device comprising at least three or more drive electrodes. The micromirror device according to any one of claims 1 to 4,
The micromirror device further includes a power source that independently controls drive voltages applied to the plurality of drive electrodes.   A mirror array comprising a plurality of micromirror devices according to any one of claims 1 to 5 arranged along a width direction perpendicular to the length direction.

Images