Researing On Terahertz Filters And Terahertz Switch Based On Photomic Crystal

Terahertz wave has some characteristics, such as high transmission bandwidth, short antenna size, and better anti-jam capability. So it applies to many fields including military communication, space communication, and security check. Eespecially indoor wireless communication. And the research for the filter and on-off control is the important part of the technology of terahertz wave communication.The terahertz filter is a most important part of the terahertz wave communication.Photonic crystal is a kind of periodic dielectric material, when the wave propagates in the photonic crystal, there will be a band gap, called forbidden band. It can’t propagate if the energy of wave is in the forbidden band. When defects are introduced to the photonic crystal, the defect mode allows wave propagates. Thus the photonic crystal can be used for the filer of wave, and realize the all-optical switch of terahertz wave. The optical switch made from photonic crystal respond speed can be ps level.We study the filtering characteristic of one dimensional photonic crystal for terahertz wave using the transmission matrix method and make a rough study the case of two dimensions. We analyze deeply on the effect of photonic lattice periods, incidence angle, and the index and the thickness of defect layer for the center frequency and intensity of the transmitted wave, proving that we can modulate the frequency of terahertz transmitted wave by changing the incidence angle or the index and the thickness of defect layer, as well as realizing the multichannel filtering and modulation of terahertz wave by changing the number of defect layers. These results can be applied for the design of optical switch. Finally, based on the GaAs photonic crystal, using LiNbO3and FLC as defect layers, we design a terahertz switch.