Terahertz (THz) sources have attracted special attention for various applications. Compared to the standard silica-based optical fibers, silicon waveguides have more advantages such as higher refractive index and lower absorption loss over the THz region. In this paper, for the first time, a rib silicon waveguide based on the photonic crystal (PC) idea is designed and by using the scalar modulation instability (SMI) phenomenon, tunable wavelength conversion for THz wave generation is simulated. By changing the structural parameters such as the air-hole diameter of the PC and infiltration of optical fluids into the air holes, linear and nonlinear characteristics of the waveguide are controlled and hence the generated THz radiation is considered as a tunable source. Simulation presents that the maximum converted wavelength, 326.17 μm, is obtained when the air-hole diameter is set at d = 0.86 μm and the pump wavelength is in the normal dispersion regime. Also, we have infiltrated optical fluids into PC air holes in order to change the dispersion properties of the waveguide while keeping the geometrical parameters unchanged. This led to converted wavelengths of 70.5, 76.8 and 107.5 μm, all located in the THz region. The loss of this waveguide is less than 0.8\( \raisebox{1ex}{$ dB$}\!\left/ \!\raisebox{-1ex}{$ cm$}\right. \), which is less than that of previously reported in similar silicon waveguides.

太赫兹 (THz) 源在各种应用中引起了特别关注。与标准的硅基光纤相比，硅波导在太赫兹区域具有更高的折射率和更低的吸收损耗等优势。在本文中，首次设计了基于光子晶体（PC）思想的肋状硅波导，并利用标量调制不稳定性（SMI）现象模拟了用于太赫兹波生成的可调波长转换。通过改变PC的气孔直径和光学流体渗入气孔等结构参数，可以控制波导的线性和非线性特性，因此将产生的太赫兹辐射视为可调谐源。仿真表明，最大转换波长为 326.17 μm，当气孔直径设置为 d = 0.86 μm 并且泵浦波长处于正常色散状态时，可以获得。此外，我们将光学流体渗透到 PC 气孔中，以改变波导的色散特性，同时保持几何参数不变。这导致 70.5、76.8 和 107.5 μm 的转换波长都位于太赫兹区域。这种波导的损耗小于0.8\( \raisebox{1ex}{$ dB$}\!\left/ \!\raisebox{-1ex}{$ cm$}\right. \)，这比之前在类似硅波导中报道的要少。