Piano MEMs micromirror
View Patent ↗A micro-electro-mechanical (MEMs) mirror device for use in an optical switch is disclosed. A “piano”-style MEMs device includes an elongated platform pivotally mounted proximate the middle thereof by a torsional hinge. The middle portion of the platform and the torsional hinge have a combined width less than the width of the rest of the platform, whereby several of these “piano” MEMs devices can be positioned adjacent each other pivotally mounted about the same axis with only a relatively small air gap therebetween. In a preferred embodiment of the present invention specially designed for wavelength switching applications, a greater range of arcuate motion for a mirror mounted thereon is provided by enabling the platform to rotate about two perpendicular axes. The MEMs mirror device according to the preferred embodiment of the present invention enables the mirror to tilt about two perpendicular axes, by the use of an “internal” gimbal ring construction, which ensures that a plurality of adjacent mirror devices have a high fill factor, without having to rely on complicated and costly manufacturing processes.
1. A micro-electro-mechanical device for pivotally supporting an optical element on a substrate comprising:
a platform for supporting the element, the platform including first and second supporting regions each defined by a width and a length, and brace means extending therebetween defined by a width and a length;
a first torsional hinge, rotatable about a first axis perpendicular to said brace means, and extending between at least one anchor post of the substrate and the platform;
wherein the total width of the first torsional hinge and said brace means is less than the width of the first or the second supporting regions, whereby a plurality of platforms pivotable about the first axis are positionable in close proximity with only an air gap between adjacent first supporting regions.
2. The device according to claim 1 , wherein said brace means comprises a single lever extending between said first and second supporting regions along an axis which includes the longitudinal central axes of the first and second supporting regions; and
wherein the first torsional hinge includes a first spring arm extending between a first anchor post and the lever, and a second spring arm extending between a second anchor post and the lever.
3. The device according to claim 2 , wherein the first spring arm includes a first serpentine spring arm; and wherein the second spring arm includes a second serpentine spring arm.
4. The device according to claim 1 , wherein the first torsional hinge includes a serpentine torsional hinge.
5. The device according to claim 1 , further comprising:
first and second electrodes positioned on the substrate beneath the first and second supporting regions, respectively, for selectively controlling the position of the platform; and
shielding positioned on opposite sides of the first and second electrodes for reducing fringing electric fields from pivoting platforms on adjacent devices.
6. The device according to claim 5 , wherein said shielding comprises shields protruding from underneath of the first and second supporting regions on opposite sides of the first and second electrodes.
7. The device according to claim 1 , further comprising:
a gimbal ring surrounding the first torsional hinge, opposite ends of the first torsional hinge being fixed to opposite sides of the gimbal ring; and
a second torsional hinge rotatable about a second axis perpendicular to the first axis, the second torsional hinge comprising first and second spring arms extending from opposite sides of the gimbal ring into contact with the first and second supporting regions, respectively.
8. The device according to claim 7 , wherein the first torsional hinge comprises first and second spring arms extending outwardly from a single anchor post, which extends upwardly from the substrate.
9. The device according to claim 8 , wherein the first torsional hinge comprises first and second serpentine spring arms extending outwardly from the single anchor post; and
wherein the second torsional hinge comprises third and fourth serpentine spring arms extending from opposite sides of the gimbal ring.
10. The device according to claim 1 , wherein upper surfaces of the first torsional hinge, the gimbal ring, the second torsional hinge and the platform are all coplanar, thereby facilitating manufacture.
11. A micro-electro-mechanical device for pivotally supporting an at least partially reflective surface on a substrate comprising:
a first torsional hinge mounted on the substrate, rotatable about a first axis;
a gimbal ring surrounding the first torsional hinge, opposite ends of the first torsional hinge being fixed to opposite sides of the gimbal ring;
a second torsional hinge rotatable about a second axis perpendicular to the first axis, the second torsional hinge comprising first and second arms extending from opposite sides of the gimbal ring, respectively; and
a platform for supporting the reflective surface connected to the second torsional hinge;
wherein the total width of the first torsional hinge, said gimbal ring and said brace means is less than the width of the platform, whereby a plurality of platforms pivotable about the first and second axes are positionable in close proximity with only an air gap between adjacent platforms.
12. The device according to claim 11 , wherein upper surfaces of the first torsional hinge, the gimbal ring, the second torsional hinge and the platform are all coplanar.
13. A micro-electro-mechanical device for pivotally supporting an at least partially reflective surface on a substrate comprising:
a first torsional hinge mounted on the substrate, rotatable about a first axis;
a gimbal ring substantially surrounding the first torsional hinge, opposite ends of the first torsional hinge being fixed to opposite sides of the gimbal ring;
a second torsional hinge rotatable about a second axis perpendicular to the first axis, the second torsional hinge comprising first and second arms extending from opposite sides of the gimbal ring, respectively; and
a platform for supporting the reflective surface connected to the second torsional hinge;
wherein upper surfaces of the first torsional hinge, the gimbal ring, the second torsional hinge and the platform are all coplanar;
wherein the platform comprises a first supporting region attached to the first arm for supporting a first reflective surface, a second supporting region with a second reflective surface attached to the second arm for supporting a second reflective surface, and a pair of braces extending between the first and second supporting regions on either side of the gimbal ring.
14. The device according to claim 11 , wherein at least one of the first and second torsional hinges includes a serpentine hinge.
15. A micro-electro-mechanical device for pivotally supporting an at least partially reflective surface on a substrate comprising:
a first torsional hinge mounted on the substrate, rotatable about a first axis;
a gimbal ring substantially surrounding the first torsional hinge, opposite ends of the first torsional hinge being fixed to opposite sides of the gimbal ring;
a second torsional hinge rotatable about a second axis perpendicular to the first axis, the second torsional hinge comprising first and second arms extending from opposite sides of the gimbal ring, respectively; and
a platform for supporting the reflective surface connected to the second torsional hinge;
wherein the first torsion hinge is mounted on the substrate via a single anchor post extending upwardly from the substrate with the first torsion hinge extending outwardly from an outer free end of the anchor post perpendicular thereto.
16. The device according to claim 13 , further comprising:
a first electrode positioned on the substrate underneath one side of the first supporting region;
a second electrode positioned on the substrate underneath one side of the second supporting region; and
a third electrode positioned on the substrate underneath another side of the second supporting region;
whereby the first and second electrodes control the pivoting of the platform about the second axis, and the second and third electrodes control the pivoting of the platform about the first axis.
17. A wavelength switch for controlling the direction of individual wavelength channels from an input optical signal to one or more of a plurality of output ports comprising:
an input port for launching the input optical signal, and for dividing the input optical signal into first and second sub-beams having the same polarization;
a dispersive element for dividing each of the first and second sub-beams into distinct wavelength channels;
a plurality of micro-electro-mechanical devices, each device for pivotally supporting first and second reflective surface on a substrate, each device comprising:
a platform including first and second supporting regions, each defined by a width and a length for supporting the first and second reflective surfaces, respectively, and brace means extending therebetween defined by a width and a length;
a first torsional hinge, rotatable about a first axis perpendicular to said brace means, and extending between at least one anchor post of the substrate and the platform proximate the brace means;
first and second electrodes positioned on the substrate beneath the first and second supporting regions, respectively, for selectively controlling the position of the platform;
wherein the total width of the first torsional hinge and said brace means is less than the width of the first or the second supporting regions, whereby the plurality of micro-electro-mechanical devices are positionable in close proximity with each other with only an air gap between adjacent first supporting regions and between adjacent second supporting regions;
whereby the micro-electro-mechanical devices are independently controllable for directing any number of the wavelength channels back to the dispersive element for recombination and output any one of the output ports.
18. The device according to claim 17 , further comprising an element with optical power for focusing and redirecting the input optical signal and the wavelength channels between the input port, the dispersive element and the micro-electro-mechanical devices.
19. The device according to claim 18 , wherein the element with optical power comprises a concave mirror.
20. The device according to claim 17 , wherein the first torsional hinge comprises:
a first serpentine spring arm extending between a first anchor post, which extends upwardly from the substrate, and the brace; and
a second serpentine spring arm extending between a second anchor post, which extends upwardly from the substrate, and the brace.