Fabrication and characteristics of a PECVD SiC evanescent wave optical sensor

This work presents a simple evanescent wave-sensing system based on plasma-enhanced chemical vapour deposition (PECVD) silicon carbide (SiC) waveguides. Thin SiC films were deposited on Si substrates with a SiO2 film acting as a cladding layer around the carbide core. In the sensor, the evanescent tale of the light travelling in a waveguide senses an absorbant medium placed above the waveguide. By using a 1 × 2 power splitter, the sensor is calibrated using one arm as a reference. This shows that the sensitivity of such a sensor is improved by choosing SiC as waveguide material compared to silicon nitride (SiN) films.