Nearly Self-Similar Pulse Compression of High-Repetition-Rate Pulse Trains in Tapered Silicon Waveguides

We numerically demonstrate a feasible way to generate a high-repetition-rate ultrashort soliton train from a dual frequency beat signal on a chip-scale silicon waveguide. A train of well-separated solitons is formed in the designed novel tapered silicon waveguide. Through the self-similar pulse compression, the pulse duration of the input pulse train is compressed from 1.5625 ps to 123.4 fs at the telecomm wavelength. Besides, the pulse propagation consists of two stages: pulse shaping and pulse compression, where the raised-cosine pulse train is evolved into the hyperbolic secant pulse train and further realize an efficient self-similar compression. The results deepen our understanding of nonlinear propagation in silicon waveguides, and open the possibility of high-repetition-rate pulse trains functionalities for ultrahigh-capacity optical communication and micro-machining in a monolithic CMOS platform.