Optimization of crosstalk and power penalty in semiconductor optical amplifiers for 10 × 80 Gb/s WDM over long transmission using soliton RZ-DPSK format

Abstract

We investigated twenty channels at 80 Gb/s wavelength division multiplexing (WDM) transmission over 910 km single mode fiber & dispersion compensating fiber using cascaded in-line semiconductor optical amplifiers at span of 70 km for soliton RZ-DPSK (return zero differential phase shift keying) modulation format. With the narrow channel spacing i.e. 200 GHz, we obtained quality more than 15dB of the received signals after covering 910 km transmission distance without any power drop. We optimize the SOA model for in-line amplifier having low cross talk in multi channel WDM systems at zero power penalty with sufficient gain. We show that for the differential gain 200 atto cm² and length 750 mm of SOA has minimum SOA induced crosstalk. The impact of optical power received and Q factor at different differential gain, carrier lifetime and length has been illustrated. It is found that for transmission distance 700 km, as we decrease the channel spacing, there is increase in crosstalk among channels hence quality of signal goes on decreasing. We show clear eye diagram and good optical spectrum is observed at the transmission distance 910 km in soliton RZ-DPSK system.