Study on the characteristics of quadruple-wavelength THz modulator base on compound lattice photonic crystal with direct-coupled structure

摘要

At present, THz wave modulator is one of the key devices in the THz communication systems. However, the response time of traditional tunable modulator based on photonic crystal is slow; it cannot satisfy the requirement of high-speed THz wave communication. In this study, a novel quadruple-wavelength THz wave modulator base on compound lattice photonic crystal with direct-coupled structure is presented. Using the direct-coupled structure formed by the combination of different line defect and point defect, the modulator is designed to be tunable by filling the point defect with nonlinear material GaAs. The device can be used to modulate the on-off state of the THz wave in quadruple-wavelength with high performance. The numerical simulation results show that the quadruple-wavelength of 59.759 μm, 64.842 μm, 60.677 μm, and 63.795 μm can be modulated at the same time. Its extinction ratio is 44.5 dB, the insertion loss is 0.23 dB and the modulation rate reaches 7.1 GHz.