Tunable dual-wavelength terahertz wave power splitter

We demonstrate, for the first time, a tunable dual-wavelength terahertz wave power splitter based on the multimode interference effect and self-imaging principle in 1 × 2 × 2 photonic crystal waveguides. Both plane wave expansion method and finite-difference time-domain method are used to calculate and analyze the characteristics of the proposed device. The simulation results demonstrate that the power splitter not only split the input power into output1 and output2 branches with equal power at frequency of 1.09 THz, but also split the power into output3 and output4 branches symmetrically at frequency of 1.20 THz. Furthermore, for the frequency of 1.09 THz, the input terahertz wave power can be split into output1 and output2 branches with an arbitrary ratio by tuning the refractive index of the tuning rods.