Optical evanescent field waveguide Bragg grating pressure sensor

A ridge waveguide Bragg grating pressure or touch sensor is proposed. The sensor consists of an open-top ridge waveguide Bragg grating with an overlaid pressure sensing polydimethylsiloxane film. The effective index of the guided mode of the waveguide is changed by stress-induced variations in the film refractive index that are caused by increases in pressure normal to the waveguide. Pressure is then measured by monitoring the shift of the Bragg resonance resulting from the changes to the effective index. By using the smaller core size ridge waveguide, and a polymer with smaller Young's modulus, the sensitivity of the sensor is enhanced. By utilizing the polarization dependence of the sensor response, a temperature-independent pressure sensor can be realized.