Variable oblique incidence for tunability in a two-dimensional photonic-crystal guided-wave filter

In this paper, the tuning mechanism for a two-dimensional (2-D) guided-wave photonic-crystal (PhC) filter obtained by varying the angle-of-incidence in the waveguide plane is demonstrated. Modeling and design of the filter have been carried out by using the Bloch-Floquet formalism. The device shows a resonance wavelength at 1550 nm for the p=30 order at normal incidence. The free spectral range (FSR) is about 38 nm and can be spanned with an in-plane angle of incidence θ ranging from 0° to 14°. The full width at half maximum (FWHM) is in the range 0.14-0.18 nm. The filter performance is suitable for 50-GHz dense-wavelength-division-multiplexing (DWDM) systems and shows that variable oblique incidence can be exploited as a tuning mechanism.