Research Of Optical Switch In THz Band Based On Two-dimensional Photonic Crystal

The terahertz radiation is between microwaves and infrared light.Due to its special prosperities such as rich spectral bandwidth,good penetrability and low-energy photons,it can carry more information in transmission and has widely application potentials in broadband communication system.With the rapid development of modern mobile communication technology,the requirement of improving the quality of THz communication will be higher and higher in the future and the THz wave device with high-performance will become the inevitable direction of development.The performance of THz wave switch directly affects the quality of the whole THz wave communication system and is one of the indispensable devices in THz wireless communication.Therefore,using photonic crystal to realize the high-speed THz wave switch with high performance become the main direction of the study.In this paper,the THz wave switching device of photonic crystal used in THz wave communication system is studied.Based on the self-collimation effect of photonic crystals and the optical properties of gallium arsenide(GaAs),two kinds of two-dimensional photonic crystal THz wave switches based on dielectric plate and dielectric column are proposed.810 nm wavelength is used as the pump light by changing the index of gallium arsenide dielectric material refractive in order to make the terahertz wave turned on and off.The optic beam can transmit without diffraction effects through the photonic crystals due to self-collimation effect.The wave switch is study by using Rsoft software combined with plane wave expansion method(PWE)and two-dimensional time-domain finite difference method(2D-FDTD).Results shows that the response time of the THz wave switch based on the dielectric plate type is 107.12 ps,the extinction ratio is 27.65 dB and the insertion loss is 0.086 dB.The response time of the two-dimensional photonic crystal THz wave switch based on the dielectric column is 116.1867 ps,the extinction ratio is 26.50 dB and the insertion loss is 0.202 dB.It has a certain angular tolerance and wavelength tolerance for the incident THz wave.