Polarization-independent multichannel wavelength conversion by difference-frequency generation in AlGaAs waveguides

Abstract

Wavelength conversion in multi-wavelength networks offers resolution of wavelength contentions and distribution of network management. It is desired in such a network that wavelength converters can simultaneously convert multiple channels at the same time so that the resulting cross- connect can scale 'the degree of wavelength conversion' as the network evolution demands such as upgrade. In addition to the multi-channel conversion capability, the wavelength converters must offer polarization independent conversion efficiency and transparency to most of the signal formats and protocols. While numerous wavelength conversion techniques have been demonstrated to date, only difference- frequency-generation offers polarization independent, strictly transparent, and multi-channel wavelength conversion without significant crosstalk. The recent experimental results obtained in AlGaAs waveguides show 17 channel wavelength conversion with no measurable cross-talk and polarization-independent conversion efficiency. The linearity to signal power levels and the spectral inversion demonstrated by experiments also imply strict transparency of the conversion process. Successful bit-error-rate measurements were obtained at both 2.5 Gb/s and 10 Gb/s, and simultaneous conversion of both 2.5 Gb/s and 10 Gb/s showed extremely low bit-error-rate with negligible cross-talk. The impact of strictly transparent wavelength converting cross- connect in multi-wavelength networks will also be discussed.