Germanium Based Two-Dimensional Photonic Crystals with Square Lattice

摘要

Using the plane-wave expansion method, we study the polarization-dependent photonic band diagrams (transverse electric and transverse magnetic polarizations), surface plots, gap maps etc. of the two-dimensional photonic crystals with square lattice of germanium rods in air and vice versa. The obtained graphs for the two possible combinations are presented in this paper. All the results depict clear photonic band gaps. We describe the conditions for the largest TE and TM band gaps too. The square lattice of Ge rods in air offers a large TE photonic band gap of 48.02% (for rod radius of r = 0.2μm). Then we localize the TE mode by introducing a point defect and a line defect in the crystal. The point defect act as a resonator and the line defect act as a waveguide. The finite-difference time-domain analysis of the localized defect modes is presented also.