Nonlinear pulse reshaping in a typically designed silicon-on-insulator waveguide and its application to generate a high repetition rate pulse train

Abstract

A silicon-on-insulator (SOI) planar waveguide is designed with a small group velocity dispersion (β 2) ∼2.212 (ps2 m−1) and a quite high nonlinear coefficient (γ) of ∼360.57 (W−1 m−1). The designed waveguide is capable of reshaping a super-Gaussian input optical pulse into a parabolic pulse (PP), without any use of external gain. The same waveguide with a relatively longer length can also generate a triangular pulse (TP) by using a positive chirp at the input. In both cases, PP and TP are created at a much shorter optimum length (L opt) of a few millimeters when compared to previously reported works on normal dispersion optical fibers. The interaction of a pulse pair inside such an SOI waveguide is investigated, for the first time as per our knowledge to generate a high-frequency (∼4.8 THz) pulse train, while lower repetition rate (∼180 GHz) pulses are used at the input. This study as a whole enables potential device applications in the domains of tunable high frequency (THz) pulse generators, optical signal processing, and many more.