Study On Tunable Complete Bandgap And Application Of Two-dimensional Annular Photonic Crystal Infiltrated With Liquid Crystal

Photonic crystal is a kind of manufactured structure with periodic arrangement of dielectric materials. Photonic bandgap structure is the primary property of photonic crystal and the base of application of photonic crystal, so the study on photonic bandgap structure is an important part of basic research on photonic crystal. At the same time, tunable photonic crystal has attracted much attention with much need of tunable optical devices. In this paper, some research has been done on the photonic band gap of two-dimensional annular photonic crystal infiltrated with liquid crystal(LC) in triangular lattice, and a novel tunable waveguide polarizer and optical switch are designed because of tunable absolute bandgaps.Photonic band gap structures of two-dimensional annular photonic crystal infiltrated with liquid crystal in triangular lattice have been calculated by the plane wave expansion method. The results show that photonic crystal structure has tunable absolute bandgaps. Moreover, analysis is carried on the relation between absolute bandgaps and structural parameters(inner radius of ring-shaped LC,outside radius of ring-shaped LC, refractive index of inner dielectric column)of two-dimensional annular PC infiltrated with LC when rotation angle of LC’s direction vector is0°or90°respectively.A tunable waveguide polarizer is designed by two-dimensional annular photonic crystal waveguides infiltrated with liquid crystal by the plane wave expansion(PWE) and finite difference time domain(FDTD) method. Three kinds of dielectric material (Al2O3, Si, Ge) have been chosen as background, and analysis is carried on the relation between the width of tunable range of polarizer and structural parameters(inner radius of ring-shaped LC, outside radius of ring-shaped LC, refractive index of inner dielectric column)of two-dimensional annular PC waveguides infiltrated with LC.Photonic band gap structures of two-dimensional LC-annular photonic crystal whose background material is SiC have been calculated by the plane wave expansion method. The results show that photonic crystal structure has tunable absolute bandgaps. Moreover, analysis is carried on the relation between absolute bandgaps and structural parameters(inner radius of ring-shaped LC, outside radius of ring-shaped LC, refractive index of inner dielectric column)of two-dimensional annular photonic crystal infiltrated with LC when rotation angle of LC’s direction vector is0°or90°respectively. Moreover, the transmission spectrums of two-dimensional annular photonic crystal waveguide infiltrated with LC are analyzed using finite difference time domain method when rotation angle of LC’s direction vector is0°or90°respectively, and the results show a polarization-independent optical switch is designed by the photonic crystal waveguide structure.