All-Optical Signal Processing Technologies in Wavelength-Division-Multiplexed Networks

The fiber Bragg grating (FBG) is one of the key elements in the established and emerging fields of wavelength-division-multiplexed (WDM) optical communication systems. In the first half of this paper, we review our research activities on FBG espe-cially focusing on the spectrum tuning technology: Tunable filter, dispersion compensator, and dispersion slope compensator are described. Third-order optical nonlinearity in optical fibers has attractive applications to all-optical signal processing that will be em-ployed in future WDM photonic networks. In the second half of this paper, after reviewing the third-order nonlinear optical prop-erty of optical fibers, we describe our research results on all-optical signal processing devices, focusing on self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM)