Optical filter and splitter based on a dropped cavity-ring resonator

The design for a metadevice on an optical platform combining two different applications is reported, namely optical filter and optical splitter. The platform is based on a dropping cavity placed in two-dimensional square photonic crystal (2D-PC). The PC-based optical filter consists of a periodic disposition of silicon (Si) cylinders in air, of radius r = 0.2 a and a dielectric constant ε = 12, while the PC-based splitter is composed of square alumina rods (Al 2 O 3 ) in air, of radius r = 0.2 a and a dielectric constant ε = 8.9. The two dropping PC waveguides, having the size w , are coupled via a cavity–ring resonator of thickness g. By controlling the geometrical parameters w and g, the incoming wavelength can be shifted or extinct.