The nonlinear optical response of an asymmetric &lgr;/4‐shifted distributed‐feedback GaAs/AlAs heterostructure is investigated using numerical methods, and also demonstrated experimentally. This structure exhibited both optical switching and bistability at incident wavelengths near &lgr;=884 nm. The observed bistability threshold of less than 1 kW cm−2is more than an order of magnitude smaller than that of any previously measured distributed‐feedback heterostructures. ©1995 American Institute of Physics.