John M. Dudley

Supercontinuum generation in a suspended core heavy metal oxide glass photonic crystal fiber

ABSTRACT In this paper we investigate supercontinuum (SC) generation in several suspended-core soft-glass photonic crystal fibers (PCFs) pumped by an optical parametric oscillator (OPO) tunable around 1550 nm. The fibers were drawn from leadbismuth- gallium-cadmium-oxide glass (PBG81) featuring a wide transmission window from 0.5 μm till 2.7 μm and a high nonlinear refractive index up to 43×10-20 m2/W. They have been specifically designed with a microscale suspended hexagonal core for efficient pumping around 1550 nm. This microstructure geometry also prevents from glass recrystallization and provides higher mechanical durability. We experimentally demonstrate two SC spectra spanning from 1.07 μm to 2.31 μm and 0.89 μm to 2.46 μm by pumping two PCFs in both normal and anomalous dispersion regimes at 1550 nm and 1580 nm, respectively. We further show a number of nonlinear phenomena such as spectral broadening due to self-phase modulation, soliton generation, and Raman soliton self-frequency shift in the fiber at the pumping wavelengths. We also numerically simulate the group velocity dispersion curves for these fibers from their scanning electron microscope (SEM) images.

Non-diffracting beam designs with Spatial Light Modulator: spatio-temporal aspects

We investigate numerically the spatio-temporal shape of non-diffracting beams generated from a Spatial Light Modulator. We show the temporal pulse shape is preserved on the main intensity lobe in the framework of ultrashort Bessel and non-paraxial accelerating beams.

Soliton generation via intrapulse stimulated Raman scattering in photonic crystal fibers: experimental and numerical investigations

We investigate femtosecond pulse propagation in photonic crystal fiber, reporting the generation of tunable femtosecond soliton pulses. For sufficiently broad spectral content, stimulated Raman scattering transfers energy from the higher frequency spectral components to lower frequencies, resulting in a continuous self-frequency shift to longer wavelengths. Power dependent spectral analysis reveals a well-formed soliton at peak powers exceeding 100 W. Background-free intensity autocorrelation measurements confirm soliton formation with a duration of < 90 fs and with an energy conversion efficiency of 60%. Numerical solutions were performed based on a generalized nonlinear Schrodinger equation that included the effects of dispersion, self-steepening, optical shock formation, self-phase modulation and stimulated Raman scattering. The resulting spectra from the simulations are in excellent agreement with the measured spectra, and are consistent with the intensity autocorrelation measurements.