Mirror based microelectromechanical systems and methods

Abstract

Unlike most MEMS device configurations which simply switch between two positions in many optical devices the state of a MEMS mirror is important in all transition positions. It may determine the characteristics of an optical delay line system and by that an optical coherence tomography system in one application and in another the number of wavelength channels and the dynamic wavelength switching capabilities in the other. The role of the MEMS is essential and it is responsible for altering the paths of the different wavelengths in either device. It would be beneficial to improve the performance of such MEMS and thereby the performance of the optical components and optical systems they form part of. The inventors have established improvements to the design and implementation of such MEMS mirrors as well as optical waveguide technologies to in-plane optical processing as well as the mid infrared for optical spectroscopy.

What is claimed is: 
     
         1 . A device comprising
 a microelectromechanical system (MEMS) formed upon a substrate; and   an optical circuit formed upon the substrate.   
     
     
         2 . The device according to  claim 1 , wherein
 the MEMS has at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator; and   the optical circuit comprises:
 a first optical circuit disposed on the platform supporting optical signal propagation within a predetermined wavelength range, the first optical circuit comprising at least one of one or more first planar waveguides each having a first surface disposed proximate the front surface of the MEMS and one or more first channel waveguides each having a second surface disposed proximate the front surface of the MEMS; and 
   a second optical circuit formed upon the substrate supporting optical signal propagation within the predetermined wavelength range, the optical circuit the second optical circuit comprising at least one of one or more second planar waveguides each having a third surface disposed proximate the front surface of the MEMS and one or more second channel waveguides each having a fourth surface disposed proximate the front surface of the MEMS.   
     
     
         3 . The device according to  claim 2 , wherein
 the MEMS is a rotatable MEMS (R-MEMS); and   rotation of the R-MEMS results in a variation of an optical delay for optical signals within the predetermined wavelength range within a predetermined portion of the second optical circuit.   
     
     
         4 . The device according to  claim 2 , wherein
 the MEMS is a rotatable MEMS (R-MEMS); and   rotation of the R-MEMS results in a variation of an optical delay for optical signals within the predetermined wavelength range within a predetermined portion of the second optical circuit; and   the device forms part of an optical coherence tomography system.   
     
     
         5 . The device according to  claim 1 , wherein
 the MEMS is a rotatable MEMS (R-MEMS); and   rotation of the R-MEMS results in a variation of an optical delay for optical signals within the predetermined wavelength range within a predetermined portion of the second optical circuit; and   the device forms part of an optical tunable delay line.   
     
     
         6 . The device according to  claim 2 , further comprising
 a second device comprising:
 another microelectromechanical system (MEMS) having at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator; 
 another first optical circuit disposed on the platform supporting optical signal propagation within a predetermined wavelength range, the first optical circuit comprising at least one of one or more first planar waveguides each having a first surface disposed proximate the front surface of the MEMS and one or more first channel waveguides each having a second surface disposed proximate the front surface of the MEMS; and 
 another second optical circuit formed upon the substrate supporting optical signal propagation within the predetermined wavelength range, the optical circuit the second optical circuit comprising at least one of one or more second planar waveguides each having a third surface disposed proximate the front surface of the MEMS and one or more second channel waveguides each having a fourth surface disposed proximate the front surface of the MEMS; 
   an input waveguide for receiving the optical signals within the predetermined wavelength range and coupling them to the device and receiving processed optical signals from the device;   a first reflector disposed between the device and the second device for receiving the optical signals from the device and coupling them to the second device and for receiving processed optical signals from the second device and coupling them to the device; and   a second reflector for receiving the optical signals from the second device and coupling them back to the second device as processed optical signals.   
     
     
         7 . The device according to  claim 2 , further comprising:
 an input waveguide for receiving the optical signals within the predetermined wavelength range and coupling them to the device;   a reflective optical grating for receiving optical signals from the device; and   an output waveguide for receiving a subset of the optical signals reflected from the reflective optical grating.   
     
     
         8 . The device according to  claim 1 , wherein
 a subset of the one or more second channel waveguides each comprise a reflective Bragg grating reflecting a predetermined portion of the optical signals within the predetermined wavelength range.   
     
     
         9 . The device according to  claim 1 , wherein
 the MEMS is a rotatable MEMS (R-MEMS) having at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator;   the MEMS actuator is coupled to the R-MEMS at an anchor;   the optical circuit comprises:
 a first optical circuit disposed on the platform supporting optical signal propagation within a predetermined wavelength range, the first optical circuit comprising a planar waveguide having a first surface disposed proximate the front surface of the R-MEMS; and 
 a second optical circuit formed upon the substrate supporting optical signal propagation within the predetermined wavelength range, the optical circuit the second optical circuit comprising at least one of a second planar waveguide having a second surface disposed proximate the front surface of the MEMS and a plurality of second channel waveguides each having a third surface disposed proximate the front surface of the MEMS. 
   
     
     
         10 . The device according to  claim 9 , wherein
 the first optical circuit further comprises a reflector disposed upon the platform distal to the front surface.   
     
     
         11 . The device according to  claim 9 , wherein
 the first optical circuit further comprises:
 a reflector disposed upon the platform distal to the front surface; and 
 a third channel waveguide having a fourth surface disposed proximate the front surface of the MEMS; and 
   the device in dependence upon a rotation angle of the R-MEMS and therein the reflector couples optical signals propagating within the third channel waveguide to a predetermined second channel waveguide of the plurality of second channel waveguides.   
     
     
         12 . The device according to  claim 9 , wherein
 the first optical circuit further comprises:
 a reflector disposed upon the platform distal to the front surface; and 
 a third channel waveguide having a fourth surface disposed proximate the front surface of the MEMS; and 
   the device in dependence upon a rotation angle of the R-MEMS and therein the reflector couples optical signals propagating within the third channel waveguide to a predetermined second channel waveguide of the plurality of second channel waveguides and reflected optical signals from the predetermined second channel waveguide of the plurality of second channel waveguides back to the third channel waveguide; and   the reflected optical signals are optical signals with a predetermined portion of the predetermined wavelength range reflected from a Bragg grating forming part of the predetermined second channel waveguide of the plurality of second channel waveguides.   
     
     
         13 . The device according to  claim 1 , wherein
 the MEMS is a rotatable MEMS (R-MEMS) having at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator;   the MEMS actuator is coupled to the R-MEMS at an anchor;   the optical circuit comprises:
 a first optical circuit disposed on the platform supporting optical signal propagation within a predetermined wavelength range having a first surface disposed proximate the front surface of the R-MEMS; and 
 a second optical circuit formed upon the substrate supporting optical signal propagation within the predetermined wavelength range, the optical circuit the second optical circuit comprising at least one of a planar waveguide having a second surface disposed proximate the front surface of the MEMS and a plurality of channel waveguides each having a third surface disposed proximate the front surface of the MEMS. 
   
     
     
         14 . The device according to  claim 13 , wherein
 the second optical circuit comprises both the planar waveguide and the plurality of channel waveguides;   the planar waveguide is disposed between the plurality of channel waveguides and the MEMS.   
     
     
         15 . The device according to  claim 13 , wherein
 the second optical circuit comprises both the planar waveguide and the plurality of channel waveguides;   the planar waveguide is disposed between the plurality of channel waveguides and the MEMS; and   the first optical circuit further comprises a reflector disposed upon the platform distal to the front surface.   
     
     
         16 . The device according to  claim 13 , further comprising
 a linear MEMS actuator coupled to the anchor; wherein   movement of a moving portion of the linear MEMS actuator moves the anchor and the platform such that the front surface of the platform in a first position is in contact with a surface of the substrate and in a second position is not in contact with the surface of the substrate.   
     
     
         17 . The device according to  claim 13 , further comprising
 one or more locking MEMS actuators having a first portion coupled to the substrate and a second portion coupled to the MEMS; wherein   in a first position the first portion and the second portion are engaged to prevent movement of the MEMS under action of the MEMS actuator; and   in a second position the first portion and the second portion are disengaged to allow movement of the MEMS under action of the MEMS actuator.   
     
     
         18 . The device according to  claim 13 , further comprising
 one or more locking MEMS actuators each having a first portion coupled to the substrate and a second portion coupled to the MEMS actuator; and   one or more gap MEMS actuators each having a third portion coupled to the MEMS actuator and a fourth portion coupled the platform; wherein   each locking MEMS actuator in a first position the first portion and the second portion are engaged to prevent movement of the MEMS under action of the MEMS actuator;   each locking MEMS actuator in a second position the first portion and the second portion are disengaged to allow movement of the MEMS under action of the MEMS actuator;   each gap MEMS actuator allows movement of the platform relative to the MEMS actuator.   
     
     
         19 . The device according to  claim 1 , further comprising
 an anchor disposed between the MEMS actuator and the platform;   an anchor spring coupled to the anchor; wherein   the MEMS is a rotatable MEMS (R-MEMS) having at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator;   the MEMS actuator is coupled to the R-MEMS at an anchor; and   the anchor spring only engages against one of the MEMS actuator and the platform above a predetermined angle of rotation of the R-MEMS.   
     
     
         20 . The device according to  claim 1 , further comprising
 an anchor disposed between the MEMS actuator and the platform;   an anchor spring coupled to the anchor; wherein   the MEMS is a rotatable MEMS (R-MEMS) having at least a front surface formed upon a substrate comprising a platform coupled to a MEMS actuator;   the MEMS actuator is coupled to the R-MEMS at an anchor; and   the geometry and dimensions of the anchor spring are established in dependence upon a required elastic characteristic of the anchor spring; and   the geometry of the anchor spring is one of a coil, rectangular, triangular, dual triangular and stepped pyramidic.