All-optical signal gating in cascaded long-period fiber gratings

Summary form only given. Using a nonlinear phase shift in a signal wave by means of cross-phase modulation (XPM) from a synchronized pump wave, we can detune transmission spectra of long-period fiber gratings (LPFG´s). Thus, the transmission loss fringe shifts to longer wavelengths when the effective index for a signal wave increases by a nonlinear phase shift due to XPM from a pump wave. Utilizing a narrow spectral loss band from an LPFG pair, we could reduce the operation intensity to less than 5 GW/cm/sup 2/. We demonstrated for the first time to the best of our knowledge that a signal wave can be gated all-optically by means of a pump wave in LPFG´s.