Optically Efficient Nonlinear Signal Processing

Optical signal processing techniques employ a wide range of devices and various nonlinearities to achieve multiple network functionalities. The choice of nonlinearity can also impact the relative efficiency, both in terms of energy and material consumption, of the signal processing function being implemented. Techniques for some of the important functionalities, wavelength multicasting, wavelength-division multiplexing to time-division multiplexing, add-drop multiplexing, and wavelength exchange are compared in terms of the used optical spectrum, number of pumps required, and optical energy consumed. These include varieties of four-wave mixing, cross-phase modulation, Kerr-effect-based polarization rotation in optical fibers, and three-wave mixing in lithium niobate waveguides (WGs). Future possibilities of greener optical signal processing using on-chip WG technologies are discussed within the scope of recent developments in the dispersion tailored, highly nonlinear WGs.