Four-wave mixing and wavelength conversion in coupled-resonator optical waveguides

The four-wave mixing process in coupled-resonator optical waveguides is considered in detail and an approximate and simple approach allowing one to estimate the conversion efficiency is proposed. The analytical results are verified through a reliable and complete numerical technique taking into account nonlinear induced phase modulations, the large-signal regime, and the pulse shape evolution along the structure. The conversion efficiency is enhanced by the slow down factor to the fourth power and the impact of attenuation and phase mismatch are carefully investigated. The main aim of this study is to provide a technique to design efficient and compact wavelength converters. Two examples of devices operating on signals at 10 and 50 Gbits/s are presented and discussed. Pulse distortions induced by chromatic dispersion, frequency detuning, and slow down factor wavelength dependence are examined and the beneficial role of the nonlinear induced phase modulation on the phase mismatch is pointed out. Numerical examples show that with typical semiconductor characteristics, very high conversion efficiencies with pump powers of only a few tenths of milliwatts are achievable