Jm. Catchmark et Dn. Christodoulides, LOSS AND NONLINEARITY SATURATION EFFECTS ON THE BISTABILITY OF NONLINEAR DISTRIBUTED-FEEDBACK STRUCTURES, Optical and quantum electronics, 29(3), 1997, pp. 393-403
We investigate theoretically the effects of optical absorption and sat
uration of the nonlinear index of refraction on the bistability of non
-linear distributed feedback structures (NLDFBs). By assuming that the
Kerr non-linearity saturates in an exponential fashion, we obtain for
the first time closed-form expressions for the so-called self-phase a
nd cross-phase modulation terms. Our investigation shows that both abs
orption and, in particular, saturation significantly affect the bistab
le properties of this structure and in many cases eliminate this respo
nse completely. In some cases, however, saturation alters the NLDFB's
transfer characteristics in a potentially useful manner. We find that
weak levels of saturation may increase the contrast ratio between the
intensities of the high and low bistable states. At increasing levels
of saturation, where bistability is no longer observed, we find regime
s where the NLDFB structure could possibly be used for optical amplifi
cation.