Off-set Filtering Effect in SOA Based Optical Access Network

Abstract

In-line and reflective semiconductor optical amplifiers (SOA and RSOA) can be effectively utilized as external optical intensity modulators. However the limited modulation bandwidth affects the application possibilities, because next generation access networks desire high transmission speed. Bandwidth enhancement can be achieved by means of optical equalization thanks to the chirping characteristics of semiconductor optical amplifier. The limited modulation transfer function can be combined with the converted phase modulation transfer function. Investigation of optical filter with optimal slope is a crucial challenge in this approach. The presented simulations describe the slope dependence of the modulation band. The model can take into account the different type of realizable optical filters. However there is a trade-off between modulation efficiency and modulation bandwidth due to the extra insertion loss of the set-off optical filter. In the paper theoretical and simulation investigations are presented with the result of improved modulation bandwidth.