  Optical bistability, the basic nonlinear phenomenon mediating the control of
light by light, paves the way to the all-optical logic being of ultimate demand
for a plethora of applications in laser information technologies. The desirable
features of the optically bistable elements are low power consumption, speed of
switching and small size. The two most general designs are driven by the
presence or absence of an external feedback giving rise to a variety of
possible setups. Among them, mirrorless architecture seems promising being free
of bulky mirrors, resonant cavities, photonic crystals, etc. In this paper, we
propose a novel method to achieve optical quasi-bistability governed by the
formation of specific nonlinear waveforms called "kinks". We show that a thin
layer of the relatively dilute resonant medium specially designed to support
kinks could serve as a platform for compact, ultra-fast, low power optical
switching. This new physical mechanism do not require high densities of
resonant particles specific for other feedback-free devices driven by local
field corrections and dipole-dipole interactions, and enhance the overall
practical relevance of such devices for optical computing.
