A simple and physically appealing theory is developed to describe the
intensity-induced ''bending'' of the stopband region of nonlinear mult
ilayered devices. The theory is subsequently used to graphically map t
he general response of devices as a function of input intensity and ph
ase detuning. Deeper insight into conventional (known) phenomena is ob
tained, while new phenomena are revealed, such as ''hard'' optical lim
iting, intensity discrimination, and a new arrangement for bistability
.