Abstract: The lifetime of free carriers in a silicon-on-insulator(SOI) rib waveguide,which is used for Raman amplification,is studied in connection with the nonlinear optical loss.An analytical expression for the free carrier lifetime in an SOI rib waveguide with a pin under a reverse bias voltage of zero,which is in accord with others’s experimental results,is presented through theoretical deduction and two-dimensional numerical simulation.The results indicate a maximum reduction of to 80% of the free carrier lifetime inside the waveguide with a pin under a reverse bias voltage of zero compared to the one with no pin.The reason for the further reduction of the free carrier lifetime after reverse biasing the pin is also studied,and the theoretical limit of the free carrier lifetime is obtained through the view of velocity saturation under a strong field.Finally,the net Raman gain of the SOI rib waveguide versus the input pump optical intensity is simulated under different free carrier lifetimes,which directs the study of silicon-based Raman amplification.

Key words: silicon-based optical interconnection, Raman amplification, SOI, rib waveguide, free carrier absorption, pin structure