Second harmonic generation in the GaAs photonic crystal line defect nonlinear waveguide

Phase matching is an important factor that affects the efficiency of nonlinear conversion. A phase matching scheme based on photonic crystal structure is proposed in this paper and the phase matching of photonic crystal was analyzed theoretically. To verify this scheme, we designed a GaAs photonic crystal line defect nonlinear waveguide. By optimizing the line defect width, the phase matching condition was successfully achieved at 288.76 THz. Furthermore, the finite element method was employed to simulate the propagation of electromagnetic wave in the device. The calculated results indicate that the nonlinear conversion efficiency of the nonlinear waveguide device reaches 43,107% (W-1cm-2), with a coherence length exceeding 103 mu m. The proposed photonic crystal structure enhances the nonlinear conversion efficiency significantly, which offers a novel approach for realizing phase matching and designing nonlinear optical devices. In addition, this scheme can also be applied to other nonlinear materials.