The impact of optical filtering on 40-Gb/s return-to-zero (RZ) signals was experimentally investigated with an optically time-division multiplexing (OTDM) receiver. Through the evaluation of the signal performance by changing the interpulse-phase conditions of the symmetrically band-limited 40-Gb/s signals, we have confirmed that the similar performance was obtained regardless of the interpulse-phase condition, owing to the pulse-reshaping capability of an OTDM receiver. The performance comparison was also conducted between the symmetrically and asymmetrically filtered 40-Gb/s RZ signals. It was found that the symmetrically filtered signal was more tolerant for the dispersion-compensation error, while the asymmetrically filtered signal was more tolerant for the fiber nonlinearity with optical filters that have a 3-dB bandwidth of 45 GHz.
Itsuro Morita, Takehiro Tsuritani, and Noboru Edagawa, "Experimental Study on Optically Band-Limited 40-Gb/s RZ Signals With Optically Time-Division Demultiplexing Receiver," J. Lightwave Technol. 20, 2182- (2002)