P.S.J. Russell

Coherent control of ultra-high frequency acoustic resonances in photonic crystal fibers

Acoustic resonances trapped within the glass core (1 mum diameter) of a photonic crystal fibre are excited electrostrictively using laser pulses. Using pulse sequences they can be coherently controlled leading to a 100-fold increase in their amplitude.

Photonic sensing based on variation of propagation properties of photonic crystal fibres

We report on a low-coherence interferometric scheme for the measurement of the strain and temperature dependences of group delay and dispersion in short, index-guiding, endlessly-single-mode photonic crystal fibre elements in the 840 nm and 1550 nm regions. Based on the measurements, we propose two schemes for simultaneous strain and temperature measurement using a single unmodified PCF element, without a requirement for any compensating components, and we project the measurement accuracies of these schemes.

Dispersive properties of rocking filters in highly birefringent photonic crystal fiber

We study the dispersive properties of the eigenmodes of rocking filters produced in highly birefringent photonic crystal fibers. The dispersion changes dramatically close to filter resonance. Rocking filters provide more flexibility in dispersion engineering.

Metal nanowire arrays in photonic crystal fibers

Metallic nanowire arrays are created by pumping molten metal into the hollow channels of silica glass PCF. Measurements show that, at certain wavelengths, the core-guided light couples to leaky surface plasmon modes on the nanowires.

Up-tapering of Optical Fibers Using a Conventional Flame Tapering Rig

We demonstrate the fabrication of low-loss up-tapers in SMF-28 using a conventional tapering rig. Waist diameters of 240 mum, uniform over several cm, have been produced. The technique also works for photonic crystal fibers.

Impulsive Raman-induced spectral broadening in hydrogen-filled HC-PCF

Hollow-core photonic crystal fibre (HC-PCF) is unique host for gas-based nonlinear optical experiments. This is because it offers low-loss single-mode guidance in a micron-sized hollow core along with pressure-tunable dispersion and nonlinearity. In previous work, noble gases have been used as Raman-free nonlinear media, permitting efficient soliton-based pulse compression where the interplay between Kerr nonlinearity and anomalous dispersion results in dramatic self-compression of an ultrashort pulse. Novel phenomena such as UV wavelength conversion and even plasma generation from ~50 fs laser pulses of ~1 μJ energy have been reported [1]. In a different context, HC-PCF filled with molecular gases offers excellent performance as an ultra-low threshold modulator and frequency shifter for nano- and picosecond laser pulses [2]. Motivated by this, here we study experimentally and numerically the propagation of a 40 fs laser pulse in a hydrogen-filled HC-PCF [3]. Since the pump pulse duration is well below the period of one rotational cycle of ortho-hydrogen (57 fs), so that the bandwidth of the pulse is broader than the corresponding Raman frequency shift (18 THz), the interaction takes place in the impulsive regime. In other words, the pump pulse already contains Stokes shifted photons and the Raman process is self-seeded. Moreover, since the pulse duration is much shorter than the phase relaxation time T2 of the molecular coherence, the (Raman) response of the medium is highly non-instantaneous (i.e., nonlocal in time) and affected by the whole pre-history of the interaction [4].

A multi-TW few-cycle optical parametric chirped pulse amplifier

We report on the generation of 8 fs, 125 mJ pulses in a noncollinear optical parametric chirped pulse amplifier with a temporal contrast reaching 10 orders of magnitude at 5 ps before the main pulse.

Microwave sound-light interactions in nanostructured photonic crystal fibres

The interaction between light and microwave sound can be strongly enhanced by tight confinement within the wavelength-scale core of a nano-structured photonic crystal fibre. A new family of efficient acousto-optical and nonlinear-optical devices is emerging.

Phase-locked anti-Stokes Raman generation in gas-filled hollow-core photonic crystal fibers

We show that the efficient non-phase-matched anti-Stokes Raman generation observed in gas-filled hollow-core PCF can be explained by phase locking of the interacting fields leading to the establishment of a phase difference independent of the optical path.

Photonic crystal fibres: A new era in the control of light

Through their unique properties - often offering orders of magnitude improvement over previous technologies - photonic crystal fibres are giving rise to numerous new applications spanning many areas of science.