P. Russell

Demonstration of ultra-flattened dispersion in photonic crystal fibers

We demonstrate photonic crystal fibers with ultra-flattened, near zero dispersion. Two micro-structured fibers showing dispersion of 0 +/- 0.6 ps/nm.km from 1.24 microm-1.44 microm wavelength and 0 +/- 1.2 ps/nm.km over 1 microm-1.6 microm wavelength have been measured.

Extruded soft glass photonic crystal fiber for ultrabroad supercontinuum generation

We report the fabrication and properties of soft glass photonic crystal fibers (PCFs) for supercontinuum generation. The fibers have zero or anomalous group velocity dispersion at wavelengths around 1550 nm, and approximately an order of magnitude higher nonlinearity than attainable in comparable silica fibers. We demonstrate the generation of an ultrabroad supercontinuum spanning at least 350 nm to 2200 nm using a 1550 nm ultrafast pump source.

Photonic crystal fiber source of correlated photon pairs

We generate correlated photon pairs at 839 nm and 1392 nm from a single-mode photonic crystal fiber pumped in the normal dispersion regime. This compact, bright, tunable, single-mode source of pair-photons will have wide application in quantum communications.

Tellurite photonic crystal fiber

We report the fabrication of a Tellurite photonic crystal fiber, and demonstrate its waveguiding properties. The measured minimum loss is 2.3 dB/m at a wavelength of 1055 nm. The fiber supports several modes, but in practice just the fundamental mode can be used. We have observed strong stimulated Raman scattering in a fiber with an effective area Aeff=21.2microm2, using sub-ns, ~ 1 microJ pump pulses at 1064.

High power air-clad photonic crystal fibre laser.

An Ytterbium-doped photonic crystal fibre laser is demonstrated with a 100 microm2 core area and single transverse mode with an output efficiency of 30 %. Double-clad PCF laser structures are demonstrated with pump cladding NA greater than 0.8 and output power up to 3.9 W. Such lasers are potentially scalable to high power.

Particle levitation and guidance in hollow-core photonic crystal fiber

We report the guidance of dry micron-sized dielectric particles in hollow core photonic crystal fiber. The particles were levitated in air and then coupled to the air-core of the fiber using an Argon ion laser beam operating at a wavelength of 514 nm. The diameter of the hollow core of the fiber is 20 m . A laser power of 80 mW was sufficient to levitate a 5 m diameter polystyrene sphere and guide it through a ~150 mm long hollow-core crystal photonic fiber. The speed of the guided particle was measured to be around 1 cm/s.

High brightness single mode source of correlated photon pairs using a photonic crystal fiber

We demonstrate a picosecond source of correlated photon pairs using a micro-structured fibre with zero dispersion around 715 nm wavelength. The fibre is pumped in the normal dispersion regime at ~708 nm and phase matching is satisfied for widely spaced parametric wavelengths. Here we generate up to 10;7 photon pairs per second in the fibre at wavelengths of 587 nm and 897 nm, while on collecting this light in single-mode-fibre-coupled Silicon avalanche diode photon counting detectors, we detect ~3.2x10;5 coincidences per second at pump power 0.5 mW.

Robust photonic band gaps for hollow core guidance in PCF made from high index glass

We report a new type of photonic bandgap that becomes substantial at remarkably low air-filling fractions (~60%) in triangularlattice photonic crystal fibres (PCF) made from high index glass (n / 2.0). The ratio of inter-hole spacing to wavelength makes these new structures ideal for the experimental realisation of hollow-core PCF in the mid/farinfrared, where suitable glasses (e.g., tellurites and chalcogenides) tend to have high refractive indices.

Scaling laws and vector effects in bandgap-guiding fibres

Scaling laws for photonic bandgaps in photonic crystal fibres are described. Although only strictly valid for small refractive index contrast, they successfully identify corresponding features in structures with large index contrast. Furthermore, deviations from the scaling laws distinguish features that are vector phenomena unique to electromagnetic waves from those that would be expected for generic scalar waves.

White-light frequency comb generation with a diode-pumped Cr:LiSAF laser

We have created a broad spectrum spanning more than an optical octave by launching femtosecond pulses from a battery operated Cr:LiSAF laser into a photonic crystal fiber. Despite the massive broadening in the fiber, the comb structure of the spectrum is preserved, and this frequency comb is perfectly suited for applications in optical frequency metrology.