Optimized wavelength conversion in silicon waveguides based on “off-Raman-resonance” operation

Starting from the propagation equations describing four-wave-mixing-based wavelength conversion, we investigate how the conversion efficiency in silicon waveguides is influenced by the frequency difference between the pump and Stokes input waves. By means of numerical simulations we show that, by detuning this frequency difference slightly away from Raman resonance, the conversion efficiency does not necessarily decrease, but can even be more than doubled as compared to Raman-resonant operation. At the same time, other values of the frequency detuning that still remain well within the Raman linewidth can lead to a more than 10 dB decrease in efficiency. As such, we show that a high-resolution tuning of the frequency difference is not only necessary to obtain an optimal conversion efficiency, but also to avoid the detrimental efficiency decrease in case of an inadequate detuning. Finally, we discuss how the pump-Stokes frequency difference that is optimal for wavelength conversion varies with the length of the waveguide and with its dispersion characteristics.

ISBN:978-0-8194-9126-8

Publication year:2012

Keywords:Nonlinear optics; four-wave-mixing;, wavelength conversion; Raman effect, silicon nanowaveguides; phase mismatch