In this paper, optical bistability behavior in a distributed feedback (DFB) semiconductor laser amplifier (SIA), with nonuniform-grating is studied. The investigation is focused on distributed coupling coefficient (DCC) structures, in which the corrugation has a nonuniform depth along the cavity, A modified implementation of transfer-matrix method, which takes the longitudinal variation of coupling coefficient along the structure into account, and considers gain saturation, is utilized to examine switching characteristics of DCC DFB SLA's in the steady state regime. Along with the wavelength dependence of bistability hysteresis. the structural dependence of switching performance in these devices is demonstrated. Low-power switching spectral range and ON-OFF contrast ratio is investigated and the results are discussed. (C) 2008 Elsevier Ltd. All rights reserved.