Ultra-fast all-optical wavelength conversion in silicon waveguides using femtosecond pulses

In this work, the propagation of 300 femtosecond optical pulses in Silicon-on Insulator waveguides has been studied by means of a pump-probe set-up. Large Cross Phase Modulation (XPM) induced red and blue shifts (9nm and 15nm, respectively) of the probe signal have been observed depending on the delay between pump (1554nm) and probe (1683nm) pulses. A numerical model taking into account Two Photon Absorption (TPA) and Free Carrier Absorption (FCA) in the semiconductor waveguide is presented and provides good agreement with the experimental data. Our model reveals that the wavelength conversion is dominated by the instantaneous optical Kerr effect, enabling ultra-fast all-optical functionalities. Furthermore, the importance of waveguide dispersion on the wavelength conversion efficiency will be treated in the case of femtosecond pulses.