Optical Pulses In Dispersive Medium Research Articles

Measurement of Net Group and Reshaping Delays for Optical Pulses in Dispersive Media

We experimentally demonstrate the direct measurement of net group and reshaping delays for arbitrary optical pulses in dispersive media, verifying the earlier prediction of Peatross et al. [Phys. Rev. Lett. 84, 2370 (2000)]. Incoherent pulse propagation in an absorptionless system is well described by net group delay; even the medium causes a great deal of deformation in the transmitted pulse. However, in the case of phase modulated chirping pulses in a resonant absorber, the so-called superluminal or subluminal propagation velocity is strongly influenced by the reshaping delay.

Angular dispersion of diffraction-free optical pulses in dispersive medium

The comprehensive analysis of angular dispersion of diffraction-free optical pulsed beams in linear dispersive medium is carried out. It is shown that properties of an angular dispersion curve essentially depend on its behavior at zero point of pulse group-velocity dispersion in the medium. As an example, the angular dispersion curves in transparency region of fused silica are presented. It is demonstrated that the radius of diffraction-free pulsed beams exhibits a strong dependence on angular dispersion.

Average energy flow of optical pulses in dispersive media

The arrival time of a light pulse at a point in space is defined using a time expectation integral over the Poynting vector. The delay between pulse arrival times at two distinct points is shown to consist of two parts: a spectral superposition of group delays (inverse of group velocity) and a delay due to spectral reshaping via absorption or amplification. The result provides a context wherein group velocity is always meaningful even for broad band pulses and when the group velocity is superluminal or negative. The result imposes luminality on sharply defined pulses.

Self-tuning of dissipative solitons to the zero-dispersion point

It is shown that optical pulses in dispersive media with dissipation and saturable broadband gain experience frequency self-shifting toward the point of zero group-velocity dispersion. The decreasing dispersion leads to a strong compression of the pulses at constant pulse energy. The ultrashort pulses that result from this evolution have a duration limited only by the third-order group-velocity dispersion of the medium. A set of solitonlike pulses is found that has a continuous spectrum of velocities, and a selection rule is presented to determine the unique solution established from an arbitrary initial pulse form.

Self-steepening of optical pulses in dispersive media

We describe an analytical solution of the modified nonlinear Schrödinger equation with the inclusion of the self-steepening term. The results are applied, in particular, to the case of pulse propagation in optical fibers; the role of anomalous dispersion is analyzed, and asymmetric temporal behavior is seen.

Propagation of short optical pulses in dispersive medium

A theoretical analysis of the propagation of transform-limited short pulses in the medium of oscillators (Lorentz model) is presented. In particular, a temporal-modes expansion of the propagating field is introduced for the nonresonance and the resonance cases. It is shown that the medium dispersion causes severe distortions in the pulse shape. The proper choice of medium parameters and/or spectral filtering of the different temporal modes may allow the formation of arbitrary pulse shapes. >

Propagation of nonlinear optical pulses in inhomogeneous media

We discuss the propagation of nonlinear optical pulses in dispersive media in the presence of inhomogeneities. Two kinds of inhomogeneities are considered, one arising due to radial variation of the refractive index of the medium and the other due to boundary conditions at the medium boundary, i.e., at the radius of an optical fiber. The wave equation is solved in the presence of these effects, taking an average of the radial dependence. It is shown that inhomogeneities have a remarkable influence on the dispersive properties of the medium, and even at normal dispersion, ’’light’’ pulses can be used for soliton transmission. Numerical results are obtained for a Nd : glass laser (λ=1.06 μm) propagating in SiO2 glass.