Integrated optical Bragg-grating-based chemical sensor on a curved input edge waveguide structure

A novel integrated optical chemical sensor based on a surface-relief Bragg grating in a waveguide with a curved input edge, and coated with a chemically sensitive polysiloxane cladding, is described. The curved edge provides a mechanism within the device fabrication that allows for alignment of the input beam to the grating to achieve Bragg scattering. As proof of principle, a low-parts-in-10(6) toluene-vapor sensor with a fast response time is demonstrated.