DOI 10.1007/s11082-006-0013-x Optical and Quantum Electronics (2006) 38:231–236 © Springer 2006 Wideband gain and noise figure modelling in SOA pascal morel 1,∗ and ammar sharaiha 1 romain brenot 2 and bruno th´ edrez 3 1 ENIB, Laboratoire RESO (EA3380), CS73286 Brest cedex, France 2 Alcatel Thales III-V lab, route de Nozay, 91461 Marcoussis cedex, France 3 ENST, 46, rue Barrault, 75013 Paris, France ( ∗ author for correspondence: E-mail: morel@enib.fr, sharaiha@enib.fr) Received 30 September 2005; accepted 31 January 2006 Abstract. Modelling Semiconductor Optical Amplifiers (SOA) is of great interest for their multi-functional application studies. We defined a wideband model thanks to SOA material gain and spontaneous emis- sion wideband definitions. We managed to fit simulations for several SOAs for a wide range of input wavelengths, bias currents and input optical powers. Key words: gain, noise figure, semiconductor optical amplifier (SOA), spontaneous emission 1. Introduction Semiconductor Optical Amplifiers (SOA) have been successfully demon- strated as all-optical multifunctional devices by exploiting such nonlinear effects as cross-phase modulation (XPM) or cross-gain modulation (XGM). In LAN and Coarse-WDM applications, SOA can also be used for linear amplification over a wide spectral range extending beyond the C or L-band of EDFAs. Accordingly, the gain and noise figure (NF) spectral dependence must be evaluated over a large spectral window requiring for such ends SOA wideband models for gain and NF. In most phenomenological models, it is assumed that the amplified spon- taneous emission (ASE) is defined thanks to a spontaneous emission (SE) factor (Talli and Adams 2003). This definition can be critical when trying to realise a wideband validity model. In this paper, we defined a polynomial function as a fundamental term of the spontaneous emission rate, which is in good agreement with physical representation over a wide bandwidth. This model will be compared with experiment by the use of two different SOA in terms of active area dimensions, gain and optical power saturation. 2. SOA bulk material model The SOA is divided into M longitudinal sections and in each section the model assumes both uniform carrier and photon densities. The SOA model