The Study On The Influence Of Point And Line Defects On Characteristic Of Non-linear Terahertz Modulator Based On Photonic Crystal

Terahertz(THz,1THz= 10 12Hz) frequency band is an electromagnetic radiation area located between the infrared and millimeter wave which can solve high-speed and ultra-broadband wireless access. THz-wave modulator is a key device in the communication system. As a new material, photonic crystal is widely used in the production of every kind of functional devices such as modulators,optical switches and filters. In actual production, however, will inevitably introduce a variety of defects and these defects will bring some impact on the performance of the modulator. In the preparation process, defects due to the growth process or artificial factors will change the structure of the modulator and the modulator is called non-ideal THz-wave modulator. It is essential to analyze the various defects on the modulator performance because it will provide a theoretical basis about producing the excellent performance of THz-wave modulator and provide foundation to promote the development of THz wave communication technology.The combination of photonic crystal technology and THz-wave modulator provides a new way of thinking.This paper firstly analyzes the principle of nonlinear THz-wave modulator based on photonic crystal and designs a structure of the modulator. The modulator uses the structure of the combination of a point defect and a line defect and introduces Gallium Arsenide (GaAs) as a tunable material. Next, this paper uses the Fullwave software based on FDTD to analyze the Extinction Ratio, modulation time and insertion loss of the modulator in the ideal state. Then this paper simulates and calculates the performance impact of various defects on this structure of the modulator mainly including the following three kinds of point and line defects: the change of radius, dislocations and deformation. The results show that the change of dielectric cylinder radius, dislocations and the change of the shape of point defect being a resonant cavity has the greatest impact on the extinction ratio and has less impact on the modulator time while it has almost no impact on the insertion loss of the modulator. According to the simulation results, this paper works out each error limit standard in order to provide a theoretical basis for high-volume manufacturing of high performance nonlinear THz-wave modulator based on photonic crystal in the future. Finally, the paper introduces the application in THz-wave communication systems of the nonlinear THz-wave modulator based on photonic crystal.