Propagation of Terahertz Pulses in Photonic Crystal-Based Rib Silicon Waveguides

Abstract

Propagation of terahertz (THz) waves in silicon waveguides is of special interest for THz applications such as optical integrated circuits. In this paper, a photonic crystal-based rib silicon waveguide with a specific structure is designed for the first time which can be utilized for applications in THz region (including wavelength range of 30-35 μm). The dispersion curve and effective index are simulated over 30–35 μm for different rib heights. In addition, the dispersion coefficients up to the third order as well as the nonlinear parameter are calculated at the center wavelength of 33 μm from which the pulse evolution along the waveguide is simulated via solving the nonlinear Schrodinger equation (NLSE). The split-step Fourier (SSF) method is used to numerically solve the NLSE and then the pulse spectra at the input and output of the waveguide are simulated and compared to each other. Also, the effect of different parameters including rib height, pulse width, chirp and peak power on the THz pulse propagation is investigated. The results show that for lengths less than 1 cm, the pulse propagates almost without distortion, while for longer lengths, the shape and spectrum of the pulse are changed.