All-optical self-switching in optimized phase-shifted fiber Bragg grating.

We experimentally demonstrate all-optical self-switching based on sub nanosecond pulse propagation through an optimized fiber Bragg grating with a pi phase-jump. The jump acts as a cavity leading to an intensity enhancement by factor 19. At pulse peak powers of 1.

Efficient collinear fourth-harmonic generation by two-channel multistep cascading in a single two-dimensional nonlinear photonic crystal.

We investigate efficient fourth-harmonic generation in a single two-dimensional (2D) quadratically nonlinear photonic crystal. We propose a novel parametric process that starts with phase-matched generation of a pair of symmetric second-harmonic waves, which then interact to produce a fourth-harmonic wave that is collinear to the fundamental. We show that this process is more efficient than conventional fourth-harmonic-generation schemes by a factor that reaches 4 at low intensities and discuss how to design and optimize the nonlinear 2D photonic crystals that are implemented in LiNbO(3) and LiTaO(3) .

Parametric amplification in presence of dispersion fluctuations.

Parametric amplification in fibers with dispersion fluctuations is analyzed. The fluctuations are modelled as a stochastic process, with their size at a given position modelled as a Gaussian, and the autocorrelation decreasing exponentially. Two models are studied: in one the dispersion is piecewise constant, while in the other it is continuous.

Two-dimensional local density of states in two-dimensional photonic crystals.

We calculate the two-dimensional local density of states (LDOS) for two-dimensional photonic crystals composed of a finite cluster of circular cylinders of infinite length. The LDOS determines the dynamics of radiation sources embedded in a photonic crystal. We show that the LDOS decreases exponentially inside the crystal for frequencies within a photonic band gap of the associated infinite array and demonstrate that there exist ;;hot' and ;;cold' spots inside the cluster even for wavelengths inside a gap, and also for wavelengths corresponding to pass bands.

Nonlinear pulse reflections from chirped fiber gratings.

We study the nonlinear evolution of optical pulses reflected from a chirped fiber grating experimentally and with numerical simulations. Over a broad range of grating parameters the nonlinearly reflected pulse splits into a pair of pulses in the range of incident pulse intensities where the transmitted pulse is a single narrowed pulse evolving into a fundamental soliton.