Polarization-dependent tunneling of light in gradient optics.

Reflection-refraction properties of photonic barriers, formed by dielectric gradient nanofilms, for inclined incidence of both S - and P -polarized electromagnetic waves are examined by means of exactly solvable models. We present generalized Fresnel formulas, describing the influence of the nonlocal dispersion on the reflectance and transmittance of single- and double-layer gradient photonic barriers for S and P waves and arbitrary angles of incidence. The nonlocal dispersion of such layers, arising due to a concave spatial profile of dielectric susceptibility across the plane film, is shown to result in a peculiar heterogeneity-induced optical anisotropy, providing the propagation of S (P) waves in tunneling (traveling) regimes.

Reflectionless tunneling of light in gradient optics.

We analyze the optical (or microwave) tunneling properties of electromagnetic waves passing through thin films presenting a specific index profile that provides a cutoff frequency when the films are used below this frequency. We show that, contrary to the usual case of a square index profile, where tunneling is accompanied by a strong attenuation of the wave due to reflection, such films present the possibility of reflectionless tunneling, where the incoming intensity is totally transmitted.

Broadband antireflection properties of thin heterogeneous dielectric films.

New exactly solvable flexible models of inhomogeneous thin film with smooth and deep variations of dielectric susceptibility epsilon(z) are presented. Formation of cutoff frequencies of such films (as well as the broadband antireflection), controlled by the profiles epsilon(z), is shown. The crucial role of gradients of epsilon(z) in the optics of strongly inhomogeneous media is emphasized.

Time character of phase-conjugate reconstructed waves.

The time dependence of phase-conjugate wave generation in liquids has been studied using four-wave mixing of picosecond laser pulses and different polarization configurations. Response and decay times of some possible physical processes contributing to the phase-conjugate wave generation have been measured.

Light-induced unidirectional light switching.

We report the first observation of a unidirectionally emitting medium obtained by the method of Doppler compensation by velocity-dependent light shifts. The emission can be switched on by a pulse of laser light. The properties of this light-switching technique are experimentally demonstrated.