JP4398433B2 - Mirror array - Google Patents

Description

The present invention relates to an optical switching device for communication, measuring instruments, but a display, a scanner, to Rumi Raarei used in the wavelength selective switch.

  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.
Although the micromirror device shown in FIGS. 9 and 10 drives the mirror with electrostatic attraction, a micromirror device and a mirror array that drive the mirror with magnetic force have also been proposed (see, for example, Non-Patent Document 1).

JP 2003-57575 A Japanese Patent No. 3444548 W.P. Taylor et al., “Magnet Arrays for Use in a 3-D MEMS Mirror Array for Optical Switching”, IEEE TRANSACTIONS ON MAGNETICS, VOL.39, NO.3, p.3286-3288, 2003

  In the micromirror device 100 shown in FIGS. 9 and 10, it is necessary to apply a large driving voltage corresponding to the tilt angle of the mirror 230 to the electrodes 340 a to 340 d during driving. Depending on the distance between the mirror 230 and the electrodes 340a to 340d, the restoring force of the torsion spring that supports the mirror 230, the area of the electrodes 340a to 340d, the relationship between the driving voltage and the electrostatic attractive force, or the inclination angle of the driving voltage and the mirror 230 However, as the drive voltage applied to the electrodes 340a to 340d, a high voltage of about 100V is necessary, for example.

By the way, if it is going to implement | achieve size reduction of the wavelength selective switch shown in FIG. 8, the mirror array which arrange | positions each micromirror apparatus (1 input 2 output optical switches 70-84) which comprises the optical switches 57-61 in proximity. It is necessary to adopt the configuration. In particular, when the number of input ports 52 to 56 and the number of output ports 66 to 69 are large, more micromirror devices are required, so that the close arrangement of the micromirror devices becomes a more urgent requirement.
However, as described above, it is necessary to apply a high voltage to the electrodes of each micromirror device, and as a result, the leakage of the electric field from each micromirror device increases, so the mirror tilt angle of a specific micromirror device is controlled. When a drive voltage is applied to the electrodes, there is a problem in that the inclination angle of the mirror of the adjacent micromirror device also changes due to leakage of the electric field from the micromirror device. Similarly, the magnetic force driven micromirror device disclosed in Non-Patent Document 1 also has a problem that the tilt angle of the mirrors of adjacent micromirror devices changes due to leakage of the magnetic field. Further, the above problems are not limited to the wavelength selective switch, and similarly occur if the configuration employs a mirror array.

The present invention has been made to solve the above problems, it aims to provide a lumi Raarei it is possible to reduce the mutual interference between the mirror devices even when disposed proximate the plurality of micro-mirror devices And

In the mirror array of the present invention , each micromirror device includes a plate-like slider, a driving means for moving the slider in a one-dimensional direction, and a plurality of sliders arranged on the slider along the one-dimensional direction. A mirror, and the driving means moves the slider to place a mirror selected from the plurality of mirrors at a predetermined position on an optical axis of incident light, and the plurality of mirrors includes the incident light. The angles of the reflecting surfaces with respect to the optical axis of the two are different from each other, and the plurality of micromirror devices are arranged along a direction perpendicular to the one-dimensional direction.

  According to the present invention, the mirror itself is not directly driven by an electric field or a magnetic field as in the prior art, but the mirror is tilted substantially by moving the slider and changing the mirror at the incident light irradiation position. Therefore, even when a plurality of micromirror devices are arranged close to each other, the tilt angle of the mirrors of adjacent micromirror devices is not affected, and mutual interference between mirror devices can be reduced.

  In addition, by moving the slider by the force generated by the electrostatic drive type micro motor, even when multiple micro mirror devices are arranged close to each other, the operation of the micro motor of the adjacent micro mirror device can be affected. Can be lowered.

  Further, by arranging a plurality of micromirror devices along a direction perpendicular to the moving direction of the slider, a large number of mirrors can be arranged within a small area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a configuration of a mirror array in which a plurality of micromirror devices according to an embodiment of the present invention are arranged.
In the micromirror device 1 of the present embodiment, an electrostatic force driven micromotor 2, a gear 3 attached to a rotating shaft of the micromotor 2, and teeth meshing with the gear 3 are formed at equal intervals on both side surfaces. The plate-shaped slider 4 is composed of three mirrors 5, 6, 7 fixed to the upper surface of the slider 4, and a power source (not shown) for supplying a driving voltage to the micromotor 2. The teeth formed on the side surfaces of the micromotor 2, the gear 3, and the slider 4 convert the rotational motion of the micromotor 2 into a linear motion and drive the slider 4 in a one-dimensional direction (the y-axis direction in FIG. 1). Means.

  FIG. 2 is a plan view showing a schematic structure of the micromotor 2, and FIG. 3 is a cross-sectional view showing a schematic structure of the micromotor 2. Similar to a general electromagnetic motor, the micromotor 2 includes a rotor 21 (rotor) integrated with the rotary shaft 20 and a stator 22 (stator) disposed around the rotor 21. The micro motor 2 is different from a normal electromagnetic motor in that a driving voltage is applied between the rotor 21 and the stator 22 to generate rotational torque due to electrostatic attraction, thereby rotating the rotor 21. As shown in FIG. 3, the rotor 21 and the stator 22 are arranged so that the respective comb-like electrodes are alternately arranged. Thereby, the distance between the comb-like electrode of the rotor 21 and the comb-like electrode of the stator 22 is reduced, and the area where the comb-like electrode of the rotor 21 and the comb-like electrode of the stator 22 are opposed is increased. A large rotational torque can be obtained with a low driving voltage. The micro motor 2 as described above is disclosed in, for example, the document “Design Wave Magazine Editorial Edition,“ MEMS Development & Utilization Startup ”, Design Wave December Special Issue, CQ Publishing Company, 2004, p.75-78”. Has been.

FIG. 4 is a cross-sectional view when the micromirror device 1 is cut along the y-axis direction. The mirrors 5 to 7 have different reflection surface angles with respect to the optical axis of incident light (in the example of FIG. 4, the direction parallel to the z axis). The reflection surface of the mirror 5 is perpendicular to the z axis, the reflection surface of the mirror 6 is inclined in the + y direction with respect to the z axis, and the reflection surface of the mirror 7 is inclined in the −y direction with respect to the z axis. Yes.
Next, the operation of the micromirror device 1 of the present embodiment will be described. 5A, FIG. 6A, and FIG. 7A are plan views for explaining the operation of the micromirror device 1, and FIG. 5B, FIG. 6B, and FIG. FIGS. 5A, 6A, and 7A are cross-sectional views taken along the y-axis direction, respectively.

  First, in the state shown in FIGS. 5A and 5B, the mirror 5 is irradiated with incident light L1 parallel to the xz plane from an input port (not shown). Since the reflecting surface of the mirror 5 is perpendicular to the z-axis, the incident light L1 is reflected in the −x direction in the xz plane. If an output port or another mirror is arranged in the direction of the reflected light L2 at this time, the reflected light L2 can be extracted.

  Next, when a driving voltage is applied to the micromotor 2 from a power source (not shown) and the motor 2 is rotated, this rotational motion is converted into a linear motion by the meshing of the gear 3 and the slider 4, and the slider 4 moves in the −y direction, for example. Moving. As a result, the mirror 6 is moved to the position of the mirror 5 in FIGS. 5A and 5B, and the state is shifted to the states in FIGS. 6A and 6B. 6A and 6B, the mirror 6 is irradiated with incident light L1 parallel to the xz plane from the input port. Since the reflecting surface of the mirror 6 is inclined in the + y direction with respect to the z axis, the incident light L1 is reflected in a direction deviating from the xz plane to the + y side. If an output port or another mirror is arranged in the direction of the reflected light L3 at this time, the reflected light L3 can be extracted.

  Next, when a driving voltage is applied from the power source to the micromotor 2 and the motor 2 is rotated in the direction opposite to that shown in FIGS. 6A and 6B, the slider 4 moves in the + y direction. Accordingly, the mirror 7 is moved to the position of the mirror 5 in FIGS. 5A and 5B, and the state is shifted to the states in FIGS. 7A and 7B. 7A and 7B, the mirror 7 is irradiated with incident light L1 parallel to the xz plane from the input port. Since the reflecting surface of the mirror 7 is tilted in the −y direction with respect to the z axis, the incident light L1 is reflected in a direction deviating from the xz plane to the −y side. If an output port or another mirror is arranged in the direction of the reflected light L4 at this time, the reflected light L4 can be extracted.

  The size of the micromirror device 1 is, for example, a length (size in the y-axis direction in FIG. 1) of 400 μm, a width (size in the x-axis direction) of 80 to 160 μm, and a pitch between the micromirror devices of 100. It is about -200 micrometers. The slider 4 and the gear 3 can be formed by a surface micromachining technique using a silicon oxide film as a sacrificial film. Regarding the formation of the wiring structure, a plating method, a lift-off method, or etching may be used. The mirrors 5 to 7 having different reflection surface angles are manufactured using a method of changing the exposure amount depending on the location. Electron beam exposure can be handled by changing the irradiation dose depending on the location. When a gray mask is used in the light exposure method, the exposure amount can be changed for each place with a single mask.

  As described above, in the present embodiment, a plurality of mirrors 5 to 7 having different reflection surface angles with respect to the optical axis of incident light are fixed on the slider 4, and the slider 4 is moved in a one-dimensional direction. Since the mirror selected from the mirrors 5 to 7 is arranged at a predetermined position on the optical axis of the incident light, the incident light can be reflected in a desired direction, so that the prior art shown in FIGS. A function equivalent to that of the micromirror device can be realized. Thus, according to the micromirror device 1 of the present embodiment, an optical switch with one input and N outputs (N = 3 in the present embodiment) can be realized.

  In the present embodiment, the mirror itself is not directly driven by an electric field or a magnetic field as in the prior art, but the mirror 4 is moved to change the mirror at the irradiation position of the incident light, whereby the tilt angle of the mirror is substantially changed. Therefore, even when a plurality of micromirror devices 1 are arranged close to each other, the tilt angle of the mirrors of adjacent micromirror devices 1 is not affected, and mutual interference between mirror devices is reduced. Can do. As described above, the micromotor 2 can obtain a large rotational torque with a low driving voltage, and the leakage of an electric field or a magnetic field from the micromotor 2 is small. Therefore, there is a possibility of affecting the operation of the adjacent micromotor 2. Can be lowered.

When a mirror array is configured using the micromirror device 1 of the present embodiment, each micromirror device 1 is perpendicular to the moving direction of the slider 4 so that the moving direction of each slider 4 is parallel. What is necessary is just to arrange | position along a direction (x-axis direction of FIG. 1). Thereby, a large number of mirrors can be arranged within a small area.
In the present embodiment, the number of mirrors per micromirror device 1 is three, but it is needless to say that the number of mirrors is not limited to this. In the present embodiment, the micromirror device 1 is used. However, it is needless to say that the incident direction is not limited to this.

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

1 is a plan view showing a configuration of a mirror array in which a plurality of micromirror devices according to an embodiment of the present invention are arranged. It is a top view which shows the schematic structure inside the micromotor in embodiment of this invention. It is sectional drawing which shows schematic structure inside the micromotor in embodiment of this invention. It is sectional drawing of the micromirror device of FIG. It is the top view and sectional drawing for demonstrating operation | movement of the micromirror device of FIG. It is the top view and sectional drawing for demonstrating operation | movement of the micromirror device of FIG. It is the top view and sectional drawing for demonstrating operation | movement of the micromirror device of FIG. 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 ... Micromotor, 3 ... Gear, 4 ... Slider, 5, 6, 7 ... Mirror.

Claims (2)

In a mirror array in which a plurality of micromirror devices are arranged two-dimensionally,
Each micromirror device includes a plate-like slider, a driving means for moving the slider in a one-dimensional direction, and a plurality of mirrors arranged along the one-dimensional direction on the slider. The means moves the slider to place a mirror selected from the plurality of mirrors at a predetermined position on the optical axis of the incident light, and the plurality of mirrors have a reflection surface with respect to the optical axis of the incident light. The angles are different from each other ,
A mirror array, wherein the plurality of micromirror devices are arranged along a direction perpendicular to the one-dimensional direction. The mirror array according to claim 1, wherein
The mirror array is characterized in that the driving means of each micromirror device moves the slider by a force generated by an electrostatic drive type micromotor .

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