Shin-Hee Won

Estimation of performance degradation of bidirectional WDM transmission systems due to Rayleigh backscattering and ASE noises using numerical and analytical models

We develop a numerical model for the transmission performance of bidirectional wavelength-division-multiplexed (WDM) transmissions. Using the numerical model, wavelength-interleaved 10-Gb/s bidirectional WDM systems are analyzed by considering the impairment of the system performance due to Rayleigh backscattering (RB). We also calculate the power penalty and the crosstalk due to RB from the analytical model, and then compare to the results obtained from the numerical model. The analytical model can provide similar results obtained from the numerical model. Both the numerical and analytical models suggest that the total isolation of filters must be more than 19.5 dB for 320-km transmission while keeping the power penalty of less than 2 dB.

Performance limits of 10-Gb/s optical duobinary transmissions using reduced bandwidth single-arm Mach-Zehnder modulators considering residual chirp and dc-bias offset

We investigate the performance limits and the impact on the system margin of 10-Gb/s duobinary modulations due to reducing the bandwidths of single-arm Mach-Zehnder (MZ) modulators in a 10-Gb/s duobinary transmitter through numerical simulation. In addition to that, the individual and combined effects of dc-bias offset ratio to switching voltage and residual chirp due to the asymmetry of modulators on the system performance have been studied using reduced bandwidth single-arm MZ modulators. Our results suggest that with a single-arm MZ modulator of bandwidth reduced to 5 GHz and a duobinary filter of 2.6-GHz bandwidth, the sensitivity penalty can be maintained within 2 dB over a 200-km span of uncompensated single-mode fiber referred to that at 0 km of ideal duobinary transmitters. In this case, the allowable range of the residual-chirp parameter is to be from -0.1 to +0.1 with dc-bias offset ratio of less than /spl plusmn/2.5%.