THz wave modulator is one of the key devices in THz wave communication systems.This paper proposes a novel dual-wavelength THz wave modulator based on the direct coupling of compound lattice photonic crystal.This modulator can realize the optical-control modulation of dual-wavelength THz waves via one point defect by introducing nonlinear material GaAs into only one point defect.The numerical simulation results show that for two different incident THz waves

this modulator has low insertion loss

high extinction ratio and high modulation rate.Compared with similar side-coupled modulators

the proposed modulator has higher extinction ratio.