M. A. Finger

Accuracy of the capillary approximation for gas-filled kagomé-style photonic crystal fibers.

Precise knowledge of the group velocity dispersion in gas-filled hollow-core photonic crystal fiber is essential for accurate modeling of ultrafast nonlinear dynamics. Here we study the validity of the capillary approximation commonly used to calculate the modal refractive index in kagomé-style photonic crystal fibers. For area-preserving core radius a(AP) and core wall thickness t, measurements and finite element simulations show that the approximation has an error greater than 15% for wavelengths longer than 0.56√(a(AP)t), independently of the gas-filling pressure. By introducing an empirical wavelength-dependent core radius, the range of validity of the capillary approximation is extended out to a wavelength of at least 0.98√(a(AP)t).

Supercontinuum generation in ZBLAN glass photonic crystal fiber with six nanobore cores

Photonic crystal fibers (PCFs) made from ZBLAN glass are of great interest for generating broadband supercontinua extending into the ultraviolet and mid-infrared regions. Precise sub-micrometer structuring makes it possible to adjust the modal dispersion over a wide range, making the generation of new frequencies more efficient. Here we report a novel ZBLAN PCF with six cores, each containing a central nanobore of a diameter ∼330  nm. Each nanobore core supports several guided modes, and the presence of the nanobore significantly modifies the dispersion, strongly influencing the dynamics and the extent of supercontinuum generation. Spectral broadening is observed when a single core is pumped in the fundamental and first higher order core modes with 200 fs long pulses at a wavelength of 1042 nm. Frequency-resolved optical gating is used to characterize the output pulses when pumping in the lowest order mode. The results are verified by numerical simulations.

Supercontinuum generation in microstructured ZBLAN fibre with six nanobore cores

We report fabrication of a microstructured ZBLAN fibre with six cores each containing a nanobore of diameter ~330 nm. Spectral broadening is observed when pumped by 1042 nm pulses in both fundamental and higher order modes.

Intensity Noise Quantification of Regenerative Amplifiers

We quantify pulse-energy fluctuations of a regenerative amplifier by online measurement of the coefficient of variation and use this to optimize the cavity dumper. Applying this method, noise influence on an OPA is studied.

Recent Advances in Soft-Glass Photonic Crystal Fibres

We report recent progress in the development of lead-silicate and fluoride-glass photonic crystal fibres. Our improved drawing technique enables the fabrication of both solid- and hollow-core fibres with unprecedented uniformity.