Thermally actuated spectroscopic optical switch

• US RE39,833 E1
• Filed: 06/13/2005
• Issued: 09/11/2007
• Est. Priority Date: 09/06/2000
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: Mitchell, Joseph Nathan, Wuest, Martin Peter
• Primary Examiner(s): Lee; John D.
• Application Number:
  US11/151,715
• Time in Patent Office: 820 Days
• Field of Search: 385 16- 22, 359/290, 359/291, 359/223, 359/224, 359/813, 359/822
• US Class Current: 385/18
• CPC Class Codes: B81B 2201/031 Thermal actuators
• CPC Class Codes: B81B 3/0024 Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators electric motors using thermal effects H02N10/00
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/3566 involving bending a beam, e.g. with cantilever
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount

Abstract

A thermally actuated spectroscopic optical switch including reflective surfaces which are selectively moved into a position intersecting a beam of light by applying electrical or heat energy to a selected composite cantilever beam on which the reflective surface is mounted.

Claims

1. A system for directing a selected light beam to at least one light beam receptor, said system comprising:

an array of stationary optical fibers, each one of said stationary optical fibers constructed and arranged to conduct one of a plurality of light beams including the selected light beam;

an optical switch fabricated on a substrate, the switch having an array of movable reflective surfaces, and having a single thermal actuator associated with each reflective surface, each thermal actuator comprising a cantilevered arm having a fixed end attached to the substrate and a free end to which the reflective surface is attached, the arm being made from a material having a thermal expansion property, the arm having a top surface and a bottom surface with a layer of material having a different thermal expansion property on a portion of at least one of these surfaces, and the cantilevered arm having an air gap between its top and bottom surfaces;

a lens at the end of each optical fiber, operable to direct the light beams to the switch or to collect light from the switch;

wherein each reflective surface is attached such that it is substantially perpendicular to the substrate; and

wherein the optical fibers are arranged around the perimeter of the substrate, such that each reflective surface is moveable into the path of one or more of the optical fibers.

2. The system of claim 1, wherein each cantilevered arm is made from a material selected from the group of single crystal silicon, polycrystalline silicon, silicon dioxide, or silicon nitride.

3. The system of claim 1, wherein the arm has a layer on each of the top and bottom surfaces and these layers have the same thermal expansion property.

4. The system of claim 1, wherein the arm has a layer on each of the top and bottom surfaces and these layers have different thermal expansion properties.

5. The system of claim 1, wherein the layers are made from a metallic material.

6. The system of claim 1, wherein each cantilevered arm is spaced from the substrate by means of an extension of the arm extending substantially vertically from the substrate.

7. The system of claim 1, wherein the application of electrical or heat energy to one of said thermal actuators will move said reflective surface into the path of the selected light beam so that the selected light beam will be directed to the light beam receptor.

8. The system of claim 1, wherein the reflective surface is rigidly attached to the arm.

9. A thermally operated optical switch for use in directing a beam of light to at least one receptor, said thermally operated optical switch comprising:

a substrate;

an array of reflective surfaces; and

a plurality of cantilever thermal actuators, each cantilever actuator having a fixed end affixed to the substrate and having a free end to which an associated reflective surface is attached such that each reflective surface has a single associated actuator, and wherein each actuator has a cantilevered arm made from a material having first thermal expansion property, each arm having an upper surface and a lower surface and having a layer of material having a second thermal expansion property on a portion of both of these surfaces;

wherein each reflective surface is attached such that it is substantially perpendicular to the substrate.

10. The thermally operated optical switch of claim 9 wherein cantilevered arm has an air gap between its top and bottom surfaces.

11. The thermally operated optical switch of claim 9 wherein each cantilevered arm is made from a material selected from the group of single crystal silicon, polycrystalline silicon dioxide, or silicon nitride.

12. The thermally operated optical switch of claim 9 wherein the arm has a layer on each of the top and bottom surfaces and the layers have the same thermal expansion property.

13. The thermally operated optical switch of claim 9, wherein the arm has a layer on each of the top and bottom surfaces and the layers have different thermal expansion properties.

14. The thermally operated optical switch of claim 9 wherein the layers are made from a metallic material.

15. The system of claim 9, wherein the application of electrical or heat energy to one of said thermal actuators will move said reflective surface into the path of the selected light beam so that the selected light beam will be directed to the light beam receptor.

16. The system of claim 9, wherein the reflective surface is rigidly attached to the arm.

17. A thermally operated optical switch for use in directing a beam of light to at least one receptor, said thermally operated optical switch comprising:

a substrate;

an array of reflective surfaces; and

a plurality of cantilever actuators, each actuator having a pair of arms, each arm of the pair having a fixed end affixed to the substrate, and the arms of each pair having a common free end to which an associated reflective surface is rigidly attached, such that each reflective surface has a single associated actuator;

wherein each reflective surface is attached such that it is parallel to the substrate.

18. The switch of claim 17, wherein the arms of each pair have different widths.

19. The switch of claim 17, wherein the arms of each pair have different lengths, such that one arm of each pair is located under the other arm of that pair.

20. The switch of claim 17, wherein each cantilevered arm is made from a material selected from the group of single crystal silicon, polycrystalline silicon, silicon dioxide, or silicon nitride.

21. The switch of claim 17, wherein each cantilevered arm is spaced from the substrate by means of an extension of the arm extending substantially vertically from the substrate.

22. The switch of claim 17, wherein the arms of each pair have different thermal expansion properties.