MEMS optical sensor
The present invention relates to an all-optical sensor utilizing effective index modulation of a waveguide and detection of a wavelength shift of reflected light and a force sensing system accommodating said optical sensor. One embodiment of the invention relates to a sensor system comprising at least one multimode light source, one or more optical sensors comprising a multimode sensor optical waveguide accommodating a distributed Bragg reflector, at least one transmitting optical waveguide for guiding light from said at least one light source to said one or more multimode sensor optical waveguides, a detector for measuring light reflected from said Bragg reflector in said one or more multimode sensor optical waveguides, and a data processor adapted for analyzing variations in the Bragg wavelength of at least one higher order mode of the reflected light.
1. An optical sensor comprising a sensor chip, the sensor chip comprising:
a hollow core waveguide defining a hollow core and comprising at least one distributed Bragg reflector,
at least one solid core waveguide adjacent the hollow core waveguide, each waveguide of the at least one solid core waveguide being configured as a respective coupling element to couple light at least one of into and out of the hollow core of the hollow core waveguide, and
at least one deflecting element configured to change at least one of geometry and dimension of the hollow core waveguide when submitted to a force.
2. The optical sensor according to claim 1 , wherein said at least one solid core waveguide has at least one of a slab geometry, a strip geometry and a rib geometry.
3. The optical sensor according to claim 1 , wherein said force originates from at least one of pressure, displacement, strain, temperature, acceleration, velocity, rotation, torque, fluid flow and temperature.
4. The optical sensor according to claim 1 , wherein two bonded substrates collectively form both said hollow core waveguide and said solid core waveguide.
5. The optical sensor according to claim 4 , wherein the two bonded substrates are selected from the group consisting of silicon substrates, silica substrates and fused silica substrates.
6. The optical sensor according to claim 4 , wherein said at least one solid core waveguide is defined vertically by at least three horizontal layers on one of the two bonded substrates.
7. The optical sensor according to claim 4 , wherein said at least one solid core waveguide is defined horizontally by vertical recessions.
8. The optical sensor according to claim 1 , wherein said at least one deflecting element forms one side of the hollow core of the hollow core waveguide.
9. The optical sensor according to claim 1 , wherein said deflecting element comprises an item selected from the list consisting of a beam, a plate, a membrane and a cantilever.
10. The optical sensor according to claim 1 , wherein said at least one deflecting element comprises at least one proof mass.
11. The optical sensor according to claim 1 , wherein said at least one distributed Bragg reflector comprises a grating.
12. The optical sensor according to claim 1 , wherein at least one of said at least one distributed Bragg reflector is located opposite the at least one deflecting element.
13. The optical sensor according to claim 1 , wherein the hollow core waveguide comprises an anti-resonance reflecting optical (ARROW) waveguide.
14. The optical sensor according to claim 1 , wherein said at least one solid core waveguide is selected from the group consisting of index guided solid core waveguides, anti-resonance reflecting optical (ARROW) waveguides, photonic crystal waveguides, and photonic band gap waveguides.
15. The optical sensor according to claim 1 , wherein geometry of the hollow core waveguide is selected from the list consisting of planar geometry only, strip geometry only, rib geometry only, and slab geometry only.
16. The optical sensor according to claim 1 , wherein each of the at least one hollow core waveguide is configured to guide at least one of a fundamental mode of single mode light and a fundamental mode and at least one higher order mode of multimode light.
17. The optical sensor according to claim 1 , wherein the maximum height of the distributed Bragg reflector is less than 25% of the maximum height of the hollow core of the hollow core waveguide.
18. The optical sensor according to claim 1 , wherein the maximum width of the hollow core waveguide is at least 10 times larger than the maximum height of the hollow core waveguide.