Abstract
We fabricate three-dimensional and two-dimensional terahertz (THz) photonic crystals (PC)by orderly stacking groove-etched high-resistance silicon wafers.The lattice structure of two-dimensional PC is triangular andthat of three-dimensional is body-centered tetragonal.In two-dimensional PC, band gaps of either polarization parallel (E-polarization)or perpendicular (H-polarization) to etched grooves are measured at normal incidence.Another structure is obtained by filling $TiO_{2}$ powder in the air rods,and the variance of band gap is analyzed.In three-dimensional PC, the transmittance through 1 to 8 stacked etched wafersare measured.By using plane-wave expansion method,we calculate the band structures discussed above.Besides, we discuss the influences of filling fraction anddielectric constant contrast on photonic band gap(PBG).The dependence of symmetry of lattice and basis on PBG is also discussed.For two-dimensional PC,the E-polarization gap-center frequency in experiment is 14% lower andH-polarization is 26% lower than that of calculation.For three-dimential PC,the gap-center frequency of experiment is 13% lower than that of calculation.The agreement between experiment and calculation is reasonable, especially inlower frequency or E-polarization.