Underwater acoustic communication systems suffer from the channel impairments which results in time spreading of the transmitted signal. In underwater environment, multiple replicas of the transmitted signal are received at the receiver through different paths, which causes significant Inter-Symbol Interference (ISI). Decision Feedback Equalizers (DFE) was utilized to overcome this type of inte...

Image retrieval based on degenerate four-wave mixing with a new nonlinear mechanism is demonstrated. An avalanche nonlinearity associated with induced excited-state absorption is exploited to furnish phase conjugation with threshold behavior and potential motion sensitivity. Population pulsations are reported at high intensities.

We model the double phase-conjugate mirror (DPCM) as a function of time, the average direction of propagation of the two beams forming the DPCM, and one transverse coordinate. Calculations show that the conjugation fidelity and reflectivity have different dependencies on the photorefractive coupling coefficient times length; the fidelity turns on abruptly with a threshold, whereas the reflectiv...

We propose and experimentally demonstrate an ultra-thin rigid endoscope (450 μm diameter) based on a passive multimode optical fiber. We use digital phase conjugation to overcome the modal scrambling of the fiber to tightly focus and scan the laser light at its distal end. By exploiting the maximum number of modes available, sub-micron resolution, high quality fluorescence images of neuronal ce...