||D. A. B. Miller, S. D. Smith and C. T.
Seaton, "Optical Bistability and Multistability in the Semiconductor InSb" in
"Optical Bistability," ed. C. M. Bowden, M. Ciftan and H. R. Robl (Plenum,
The discovery of third-order refractive nonlinearity with X^3 ~
10^-2 esu has led to the observation of optical bistability in thin parallel crystals of
InSb in various orders. The effect is so sensitive that it is observable at power
densities ~ 10 W/cm^2 (mW incident powers) using 100 um dimension devices. Transphasor
action, that is, two-beam differential signal gain analogous to transistor action, has
been observed with gains of up to 10. The future prospects of these devices are disussed
in terms of macroscopic and microscopic processes, for both of which new theory has been
developed, and the possibility of fast, low-power switching is discussed.