Photonic crystal based add/drop filters for sensing

We report design and simulations of photonic crystal based add/drop filter. Simulations for spectral analyses of propagated light and simulations for investigation of dispersion diagram are performed by finite-difference time-domain (FDTD) simulation method and plane wave expansion (PWE) method respectively. Add/drop filter is created as a key part of sensor application. Additional element with certain refractive index in design of add/drop filter reflects sensed humidity and by shifted spectral response of add/drop filter.