Ultra-narrow asymmetric filter for transmission with 0.8 bit/s/Hz spectral efficiency

A novel approach is proposed to ultra-narrow optical filtering in dense WDM transmission. The filter based on fiber Bragg grating is specially designed and fabricated to be slightly asymmetric. A feasibility of 8/spl times/40Gbit/s DWDM RZ transmission with 0.8 bit/s/Hz spectral efficiency (without PDM and FEC) over 1280 km of SMF/DCF link has been confirmed by numerical modelling.