Analytical Prediction for Quasi-TE mode in Silicon Nanowire Optical Rectangular Waveguide

Abstract

Theoretical and numerical mode estimation performed on Silicon Nanowire Optical Rectangular Waveguide (SNORW) is presented for on-chip communication in photonic integrated circuits. The propagation behavior of electric and magnetic fields is investigated, where zeroth order mode is found dominating inside the nanoslot region of SNORW for the circularly symmetric quasi-TE mode to propagate. This SNORW structure supports hybrid mode, which derives its behavioral root from the rectangular waveguide and functional root from the slot waveguide. In periodic silicon nanowire-based waveguide, it is found that the envelope of mode field intensity closely matches with rectangular waveguide and the guiding properties closely matches with slot waveguide. The type of mode is analyzed by full vectorial Finite Element Method (FEM) and the analytical expression is derived using Effective Index Method (EIM). Analytical expressions are used to express Quasi-TE mode in term of material profile and waveguide physical parameters. The results obtained for SNORW in S, C and L wavelength bands are compared with the earlier reported work on slot waveguide, and the field intensity obtained with the theoretical equations is also compared with that of FEM results.