Study on Band Gap Structure of Two-dimensional Photonic Crystals with Square Lattice

The plane wave expansion method was used to calculate the bandgap of two-dimensional square lattice photonic crystals with square columns formed by GaAs and Ge.The influences of crystal structures and refractive index on photonic bandgap properties were investigated.It showed that the maximum complete photonic bandgap was produced when the rotation angle was 0°.For the photonic crystals formed by the materials with different refractive indexes,while the refractive index n was equal to 2.57,the complete photonic bandgap appeared.The fact provides a possibility for the construction of photonic crystals with low refractive index material.As n was 4.10,the width of complete photonic bandgap reached the maximum value.The results supply the theoretical basis for the application of photonic crystals.