Dimensionality and size of photorefractive spatial solitons.

We study experimentally self-trapping of optical beams in photorefractive media and show that the trapping is inherently asymmetric with respect to the two (transverse) trapping dimensions. We also present experimental results that show how the sizes of the resultant photorefractive spatial solitons are independent (within their range of existence) of the amplitude of the externally applied electric field used to generate them.

Stability of photorefractive spatial solitons.

We present a theoretical analysis of the stability of photorefractive spatial solitons along with experimental results that show that the solitons are stable for small-scale perturbations but break down when the perturbations exhibit a transverse scale comparable with the soliton size (cross section).

Maximum fractional energy transmissible over a linear dispersive medium.

We investigate the problem of transmitting the maximum fractional energy over a given length of a linear dispersive medium (e.g., a single-mode optical fiber) once the input pulse duration and the output detection time are assigned.

Coupled-mode theory approach to depolarization associated with propagation in turbulent media.

The problem of light depolarization in a turbulent atmosphere is revisited by means of coupled-mode theory [D. Marcuse, Theory of Dielectric Optical Waveguides (Academic, New York, 1974)]. This allows, in particular, evaluation of the depolarization ratio for a plane wave and comparison of its expression with the one obtained in the frame of two distinct approaches predicting different behaviors [A. A. M. Saleh, IEEE J. Quantum Electron. QE-3, 540 (1967); J. W. Strohbehn and S. F. Clifford. IEEE Trans Antennas Propag. AP-15,416 (1967)]. It is shown that both approaches give the same result when calculated to the same order in both smallness parameters relevant to the problem, thus resolving a controversy of more than 20 years.

Phase conjugation by degenerate four-wave mixing and temporal coherence.

The influence of the temporal-coherence properties of the pump and signal waves on the efficiency and the temporal fidelity of the phase-conjugation process associated with degenerate four-wave mixing is examined.

Coupled-mode theory approach to nonlinear pulse propagation in optical fibers.

The formalism of coupled-mode theory is adopted for describing nonlinear pulse propagation in optical fibers, the coupling being induced by the nonlinear part of the refractive index. This approach describes in a natural way the influence of the waveguide, and in principle allows of the possibility of investigating soliton propagation when more than one mode is excited.

Soliton propagation in multimode optical fibers.

Soliton propagation in a multimode optical fiber in the presence of an intensity-dependent refractive index is investigated by means of a set of nonlinear coupled equations derived in the frame of coupled-mode theory. In particular, the conditions on modal amplitudes and modal dispersion necessary for soliton existence are derived.