Investigation on characteristics of 3-D function photonic crystal

In order to study photonic band gap of 3-D functional photonic crystal, dispersion curve was calculated by using plane wave expansion method. Correlation calculation formula of plane wave expansion method and function relation of dielectric constant of dielectric sphere were derived. The effects of the adjustable parameter I and dielectric sphere radius R₁ on photonic band gap were discussed. The result shows that, 3-D function photonic crystal is cube lattice distribution and air background is filled with medium ball. Compared with conventional 3-D dielectric photonic crystals, 3-D function photonic crystal can obtain the tunable photonic band gap, expand the bandwidth of forbidden band, and increase the number of photonic band gaps. The number, position and bandwidth of photonic band gaps can be tuned by changing the size of tunable parameter I. At the same time, the bandwidth and position of photonic band gaps can be tuned by changing the sphere radius R₁ of the medium. The study is helpful for the design of new tunable devices.