Karen Marie Hilligsøe

Supercontinuum generation in a photonic crystal fiber with two zero dispersion wavelengths

We demonstrate supercontinuum generation in a highly nonlinear photonic crystal fiber with two closely lying zero dispersion wavelengths. The special dispersion of the fiber has a profound influence on the supercontinuum which is generated through self-phase modulation and phasematched four-wave mixing and not soliton fission as in the initial photonic crystal fibers. The supercontinuum has high spectral density and is extremely independent of the input pulse over a wide range of input pulse parameters. Simulations show that the supercontinuum can be compressed to ultrashort pulses.

Continuous-wave wavelength conversion in a photonic crystal fiber with two zero-dispersion wavelengths.

We demonstrate continuous-wave wavelength conversion through four-wave mixing in an endlessly single mode photonic crystal fiber. Phasematching is possible at vanishing pump power in the anomalous dispersion regime between the two zero-dispersion wavelengths. By mixing appropriate pump and idler sources, signals in the range 500-650 nm are obtained in good accordance with calculated phasematching curves. The conversion efficiency from idler to signal power is currently limited to 0.3% by the low spectral density of the pump and idler sources at hand, but can be greatly enhanced by applying narrow line width lasers.

Stability of gap solitons in a Bose-Einstein condensate

We analyze the dynamical stability of gap solitons formed in a quasi-one-dimensional Bose-Einstein condensate in an optical lattice. Using two different numerical methods we show that, under realistic assumptions for experimental parameters, a gap soliton is stable only in a truly one-dimensional situation. In two and three dimensions, resonant transverse excitations lead to dynamical instability. The time scale of the decay is numerically calculated and shown to be large compared to the characteristic time scale of solitons for realistic physical parameters.

Pulse propagation in photonic crystal fibers

We investigate nonlinear effects of pulse propagation in photonic crystal fibers. In particular we study the onset of supercontinuum generation both theoretically and experimentally, with emphasis on varying the pump power and pump wavelength.

Alignment of neutral molecules by a strong laser field

Summary form only given. The use of cw lasers to manipulate the external degrees of freedom of atoms is a central subject of atomic physics. Here, we report experimental evidence that a strong, nonresonant, linearly polarized, laser pulse can align a sample of neutral molecules without causing ionization or dissociation.