Optical path clearing and enhanced transmission through colloidal suspensions.

We utilize advanced laser fields to clear a path through a dynamic turbid medium, a concept termed "Optical path clearing (OPC)." Particles are evacuated from a volume of the medium using the gradient and/or scattering forces due to an applied laser field with a suitably tailored spatial profile. Our studies encompass both an analytical model and proof-of-principle experiments where paths are cleared in dense bulk colloidal suspensions. Based on our results we suggest that high-performance and high efficiency OPC will be achieved by multiple-step clearing using dynamic laser fields based on Airy or inverted axicon beams.

Potential optical gain with two crossed Fabry-Perot resonators: the influence of absorption.

A crossed resonator Fabry-Perot device is analyzed for a collection of nonlinear-optical materials, including bulk semiconductors, the intraband transition in a multiple quantum well, organic polymers, and semiconductor-doped glasses, to determine its suitability for photonic switching and optical computing. We find that as an optical switch the crossed resonator offers a considerably steeper threshold and somewhat flatter wings than a single Fabry-Perot resonator and that to achieve optical gain the absorption per pass must be lower than 0.05.

Generation of squeezed states by nondegenerate multiwave mixing in two-level media.

Using our quantum theory of multiwave mixing, we derive formulas for the intracavity squeezed variances generated by nondegenerate four-wave mixing in a cavity and illustrate the results with variance spectra as functions of side-mode/pump beat frequency.

Imaging and target detection with a heterodyne-reception optical radar.

A mathematical system model for a compact heterodyne-reception infrared radar is developed. This model incorporates the statistical effects of propagation through atmospheric turbulence, target speckle and glint, and heterodyne-reception shot noise. It is used to find the image signal-to-noise ratio of a matched-filter envelope-detector receiver and the target detection probability of the optimum likelihood ratio processor. For realistic parameter values it is shown that turbulence-induced beam spreading and coherence loss may be neglected. Target speckle and atmospheric scintillation, however, present serious limitations on single-frame imaging and target-detection performance. Experimental turbulence strength measurements are reviewed, and selected results are used in sample performance calculations for a realistic infrared radar.