Abstract-RSOA is considered a strong candidate to play an important role in realizing the next generation WDM PON, based on the wavelength reuse concept. Therefore, accurate and efficient modeling of RSOA is of significant importance.We present a time-domain wideband model for simulation of spatial and temporal distribution of photons and carriers in a bulk RSOA. A trade-off between the accuracy and the computational efficiency of the model is studied. Multi-objective genetic algorithm is utilized for parameter extraction. Experimental validation has been performed for continuous wave input, NRZ and QPSK signaling pulses up to 40 Gb/s of bit rate, in both amplification and remodulation regimes. Saturation, noise, chirp and signal broadening are successfully predicted, while reducing the computational time compared to other wideband models.Index Terms-modeling, optical communications, QPSK, reflective semiconductor optical amplifiers, remodulation.
I. INTRODUCTIONEFLECTIVE semiconductor optical amplifiers (RSOA) have drawn considerable attention in recent years, especially for their feasibility in cost and complexity sensitive broadband access solutions [1,2]. In particular, wavelength division multiplexing passive optical network (WDM PON) technology increasingly relies on the colorless optical network unit (ONU) concept, often based on carrier regeneration and remodulation by means of RSOA [3][4][5]. Moreover, RSOA has been recently used in coherent scenarios, for generation of advanced phase shift keying modulation formats [6,7]. Accurate and computationally efficient modeling for the device can thus be an important asset in efforts of defining the conditions for feasibility of such scenarios.Upon its propagation through RSOA waveguide structure, a signal is subjected to dynamic effects that can be somewhat expected to be similar to those in a conventional semiconductor optical amplifier (SOA). However, fiber-to- Aveiro, ali@av.it.pt; natasa@av.it.pt; teixeira@av.it.pt).R. P. Dionísio is with the Department of Electronics and Telecommunications, Castelo Branco Polytechnic Institute, Castelo Branco, 6000-767 Portugal (e-mail: rdionisio@ipcb.pt).fiber optical gain, noise figure (NF) and saturation characteristics of RSOA can be quite different in comparison. In describing those effects one can therefore not fully rely on well described numerical models for SOA, as the effects of counter-propagation will considerably affect the longitudinal distribution of photon and carrier densities. Furthermore, pulse propagation effects ought to be systematically studied by using dynamic modeling, rather than steady-state one [8], since RSOA is no longer employed at relatively low remodulation bitrates (i.e. 1 Gb/s or less) due to novel solutions for overcoming its limited modulation bandwidth [4,5]. Experimentally verified theoretical investigation of pulse propagation dynamics in RSOA has been recently reported [9]. However, it is of interest to provide a more general modeling including the noise contribution, supported by...