Trapezoid 2D photonic crystal nanoring resonator-based channel drop filter for WDM systems

In the present work, a nanostructure of trapezoid photonic crystal ring resonator-based channel drop filter is designed for wavelength division multiplexing systems (WDM) to drop a channel at a center peak wavelength of 1543 nm. The proposed channel drop filter is composed of bus waveguide, drop waveguide, trapezoid nanoring resonator and reflector in a two-dimensional (2D) hexagonal lattice with circular rods arranged in air host. The trapezoid nanoring resonator is playing a very important role in WDM systems for dropping a single channel over a wide wavelength range. The photonic band gaps of perfect lattice structure and non-perfect lattice structure are absolutely calculated by plane wave expansion method. The functional properties of the designed filter are evaluated by finite difference time domain method (FDTD). The functional properties are center peak wavelength, dropping efficiency, passband width and quality factor. The FDTD method results show dropping efficiency is 100%, and quality factor is about 514.33 which are highly suitable for WDM systems. Further, lattice constant, inner and outer rod radius and refractive index difference of the structure are varied to tune the filter center peak wavelength and its corresponding functional parameters effects are investigated. The proposed nanoring resonator-based optical filter is ultra-compact size around \(14\, \upmu \hbox {m} \times 8.4\, \upmu \hbox {m}\); hence, it is extremely suitable for WDM-based photonic communication systems and photonic integrated circuits.