Dispersive properties of quasi-phase-matched optical parametric amplifiers

The dispersive properties of non-degenerate optical parametric amplification in quasi-phase-matched (QPM) nonlinear quadratic crystals with an arbitrary grating profile are theoretically investigated in the no-pump-depletion limit. The spectral group delay curve of the amplifier is shown to be univocally determined by its spectral power gain curve through a Hilbert transform. Such a constraint has important implications on the propagation of spectrally-narrow optical pulses through the amplifier. In particular, it is shown that anomalous transit times, corresponding to superluminal or even negative group velocities, are possible near local minima of the spectral gain curve. A possible experimental observation of such effects using a QPM Lithium-Niobate crystal is suggested.Comment: submitted for publicatio

Rotating optical soliton clusters

We introduce the concept of soliton clusters -- multi-soliton bound states in a homogeneous bulk optical medium, and reveal a key physical mechanism for their stabilization associated with a staircase-like phase distribution that induces a net angular momentum and leads to cluster rotation. The ringlike soliton clusters provide a nontrivial generalization of the concepts of two-soliton spiraling, optical vortex solitons, and necklace-type optical beams.Comment: 4 pages, 5 figure

Light guiding light: Nonlinear refraction in rubidium vapor

Recently there has been experimental and theoretical interest in cross-dispersion effects in rubidium vapor, which allows one beam of light to be guided by another. We present theoretical results which account for the complications created by the D line hyperfine structure of rubidium as well as the presence of the two major isotopes of rubidium. This allows the complex frequency dependence of the effects observed in our experiments to be understood and lays the foundation for future studies of nonlinear propagation

Asymptotic Studies of Closely Spaced, Highly Conducting Cylinders

We consider the solution of the scalar transport problem for a pair of nearly touching cylinders of high conductivity. We obtain an expression for the set of multipole moments of the potential distribution for this problem in terms of the hypergeometric function. We apply this expression in the estimation of truncation errors occurring in the matrix solution of the corresponding transport problem for the square array of cylinders. Consequently, we are able to calculate the array transport coefficient for arbitrarily high cylinder conductivities, and arbitrarily small cylinder separations. We derive and verify an expression for this coefficient which is uniformly valid throughout the whole asymptotic region when highly conducting cylinders approach touching

Extruded single-mode non-silica glass holey optical fibres

The fabrication of the first microstructured singlemode non-silica optical fibre is reported. Extrusion has been used for the first time to produce the microstructured fibre preform. The final drawn fibre has an effectively air-suspended 2 µm core. Singlemode guidance is observed from 633-1500 n

Fabrication and optical properties of lead silicate glass holey fibers

We report on recent progress in lead silicate holey fibers for non-linear device applications. Improvements in the fabrication have resulted in core diameters as small as 1.7 µm, increased air-suspension of the core and reduced propagation loss of 2.6 dB/m. This small core fiber exhibits a record non-linearity of 640 W-1 km-1