Observation of the time-reversed replica of a monochromatic optical wave

Abstract
We have generated, essentially instantaneously, a time‐reversed (TR) replica (phase conjugate) of a monochromatic optical wave (at 6943 Å). Replication occurred through an interaction with a standing pump wave (at the same frequency) mediated by the instantaneous nonlinear refractive index of liquid CS2. The power in the TR replica could be made up to half that in the beam being replicated before other nonlinear effects intervened.