Multi-Channel Cascadable Parametric Signal Processing for Wavelength Conversion and Nonlinearity Compensation

The dissemination of the digital coherent technology has enabled the recent growth of information networks, which has obviated signal processing in the optical domain such as optical dispersion compensation. However, the further scaling of the digital coherent technology will eventually suffer from the slowdown of the Moore's law and/or the energy crunch as a result of the longstanding relentless traffic increase. The use of all-optical signal processing, free from the electronic limitations, will then inevitably be reevaluated but in a slightly different way from how it was previously expected. In this paper, we highlight the unique features of all-optical signal processing that outperforms digital signal processing, and review the two latest results: one is upgrade-free, multi-channel wavelength conversion; and the other, all-optical back propagation for WDM channel nonlinearity compensation. Both of these functions are exploiting a versatile physical phenomenon of parametric processes in highly nonlinear fiber that is highly efficient in terms of cost and energy and is as cascadable as EDFAs. This paper discusses their practical aspects with emphasis on cascadability. In particular, the promising prospects for “cascaded phase-conjugating amplifier chains” to compensate nonlinear signal distortion will be highlighted after discussing the parameter tolerances for all-channel nonlinearity compensation.