Background

There is a growing need for micro-sensors with faster response and higher sensitivity. Micro-sensors based on integrated optics can potentially detect and transmit signals without the use of electrical wires. The clear advantages of optical micro-sensors are immunity to electromagnetic interference, safety in explosive media, electrical passivity, and good sensitivity with high dynamic range. Among the diverse micro-sensors currently being developed, PC (Photonic Crystal) sensors have drawn much attention because of their high sensitivity, very small footprint area, possibility for distributed measurements and potential integration with well established SOI (Silicon- On-Insulator) technology.

Description of the Invention

A micro-photonic pressure sensor based on PC waveguides is fabricated using planar SOI technology. The principle of operation of the device is to use changes in refractive index of the material surrounding a micro-photonic waveguide to change the transmission of light through the waveguide. In this sensor, an active micromechanical sensing element consisting of an air-bridge suspended optical waveguide converts a mechanical external input (force, pressure, acceleration, etc.) into an optical signal output via an optical readout. The deflection of the membrane effectively changes the refractive index in the vicinity of the PC waveguide changing the transmission through the waveguide. The waveguide response is very sensitive to even nanometre deflections to the membrane, providing an ultra-sensitive sensor. By combining optical and mechanical properties of the structure, the change in intensity and spectral shift of light transmitted through the waveguide has been simulated as a function of external force, allowing the design of sensors to detect a range of forces.

Potential Advantages

Ø      Higher sensitivities achievable with smaller footprint than existing sensors

Ø      Possible to fabricate an array of sensors with varying sensitivity on same substrate

US Provisional Patent Filed