Optical cantilever based analysis
An optical sensor including a MEMS structure, and a grating coupled resonating structure positioned adjacent to the MEMS structure, the grating coupled resonating structure comprising an interrogating grating coupler configured to direct light towards the MEMS structure. The interrogating grating coupler is two dimensional, and the interrogating grating coupler and the MEMS structure form an optical resonant cavity.
1. An optical sensor including:
a MicroElectroMechanical Systems (MEMS) structure; and
a grating coupled resonating structure positioned adjacent to the MEMS structure, the grating coupled resonating structure comprising:
an input grating coupler for inputting light into the optical sensor;
an output grating coupler for outputting light from the optical sensor; and
an interrogating grating coupler configured to direct light towards the MEMS structure and collect light reflected by the MEMS structure; wherein
the input grating coupler and the output grating coupler are spaced a distance from the interrogating grating coupler;
the interrogating grating coupler has a plurality of holes in a two dimensional array forming a two dimensional grating; and
the interrogating grating coupler and the MEMS structure form an optical resonant cavity.
2. The sensor of claim 1 wherein the MEMS structure is a cantilever.
3. The sensor of claim 1 wherein the array is a regular shape.
4. The sensor of claim 3 wherein the array forms a square.
5. The sensor of claim 3 wherein the array forms a rectangle.
6. The sensor of claim 1 wherein the array is an irregular shape.
7. The sensor of claim 1 wherein the holes are etched in a Silicon on Insulator (SOI) layer.
8. The sensor of claim 7 wherein the SOI layer is formed on a Buried Oxide (BOX) layer.
9. The sensor of claim 8 wherein the BOX layer is formed on a substrate.
10. The sensor of claim 8 wherein a waveguide layer is formed on the BOX layer.
11. The sensor of claim 1 wherein each hole is cylindrical in shape.
12. The sensor of claim 1 wherein the input grating coupler is one dimensional.
13. The sensor of claim 1 wherein the input grating coupler includes a plurality of holes forming an array.
14. The sensor of claim 1 wherein the output grating coupler is one dimensional.
15. The sensor of claim 1 wherein the output grating coupler is two dimensional.
16. The sensor of claim 1 wherein the output grating coupler includes a plurality of holes forming an array.
17. A method of detecting a deflection of a MEMS structure, the method comprising the steps of:
inputting an optical signal into an input grating coupler;
inputting the optical signal from the input grating coupler into an interrogating grating coupler, the interrogating grating coupler being arranged to form an optical resonant cavity with the MEMS structure;
inputting the optical signal from the interrogating grating coupler to an output grating coupler, wherein the input granting coupler and the output granting coupler are spaced a distance from the interrogating granting coupler; and
analyzing the optical signal output from the interrogating grating coupler to determine a deflection of the MEMS structure; wherein
the interrogating grating coupler includes a plurality of holes in a two-dimensional array.
18. The method of claim 17 wherein the MEMS structure is a cantilever beam.
19. The method of claim 17 wherein the input grating coupler is two dimensional.
20. The method of claim 17 wherein the output grating coupler is two dimensional.