Two Dimensional (2D) circular Photonic Crystal Ring Resonator (PCRR) based Add Drop Filter (ADF) is designed and the impacts of rod shape with its filling fraction is examined to evaluate the performance of the filter. The ADFs are devised separately using rods of circular, hexagonal and square shape in square lattice PC. For various values of rod’s cross sectional dimension and shape, the resonant wavelength, coupling efficiency, dropping efficiency, Q factor and passband width of the designed filters are investigated through simulation. The calculated filling fraction of a square, circular and hexagonal rods in the lattice structure is 11.9006 × 10-12 sq.m, 13.1134 × 10-12 sq.m and 15.16 × 10-12 sq.m and their respective resonant wavelength is 1494 nm, 1504 nm and 1520 nm. It is observed that there is 1 nm wavelength shift to longer wavelength while increasing the overall filling fraction by 0.1233 × 10-12 sq.m. From the simulated results, it is observed that the circular and hexagonal rods based ADF impart better performance than square rod based ADF.
Photonic crystal; photonic band gap; rod shape; add drop filter
