Numerical investigation on the femtosecond pulse propagation and free carriers’ evolution in silicon-on-insulator waveguides

The femtosecond pulse propagation and free carriers’ evolution in the silicon-on-insulator (SOI) waveguides have been numerically investigated considering the carrier’s lifetime and the pulse width of the input pulse at 1.5 μm regime. Numerical results show that the free carriers’ density profile becomes gentle between the leading edge and trailing edge of the pulse in time domain due to the decreasing of the pulse intensity caused by the nonlinear absorption, which becomes more remarkable when the pulse width expands. It can be found that lifetime ranging from 5 ns to 100 ns does not affect the free carriers’ evolution clearly in femtosecond regime. In addition, the refractive index modulation can be appeared in the process of pulse propagation and free carriers evolution with lower peak power of 200 W. This research can supply some contribution to the insight of free carriers evolution in SOI waveguides.