Showing papers by "Philip St. J. Russell published in 2010"
TL;DR: The nonlinear propagation of pulses in liquid-filled photonic crystal fibers is considered and the nonlinear modes propagating inside such structures can be approximated, for pulse durations much shorter than the molecular relaxation time, by temporally highly nonlocal solitons, analytical solutions of a linear Schrödinger equation.
Abstract: The nonlinear propagation of pulses in liquid-filled photonic crystal fibers is considered. Because of the slow reorientational nonlinearity of some molecular liquids, the nonlinear modes propagating inside such structures can be approximated, for pulse durations much shorter than the molecular relaxation time, by temporally highly nonlocal solitons, analytical solutions of a linear Schrodinger equation. The physical relevance of these novel solitons is discussed.
64 citations
TL;DR: In this article, a pressure-assisted filling of low-melting-point chalcogenide and tellurite glasses into silica matrix fibers with channel diameters as small as 200 nm is described.
Abstract: All-solid photonic crystal fibers (PCFs) are created by pressure-assisted filling of low-melting-point chalcogenide and tellurite glasses into silica matrix fibers with channel diameters as small as 200 nm Overcoming to a large extent the problem of viscosity and, thus, process incompatibility of silica and non-silicate optical glasses, the technique provides a unique way of producing waveguiding devices with high core-cladding index-contrast, high optical non-linearity and a transmission range that extends into the mid infrared In this paper, as a prerequisite for waveguide production, the rheologic properties and controlled flow of highly-viscous liquids under geometrically confined conditions are considered, and deviations from Newtonian behavior are discussed Because the filling process requires only very small quantities of filling material that do not come into contact with the environment, and because ultra-high cooling rates can be achieved, the technique enables the use of difficult-to-handle or reactive optical glasses
45 citations
TL;DR: The use of a liquid-filled hollow-core photonic crystal fiber (PCF) as a highly controlled photochemical reactor implied that even systems with very small quantum yields can be measured very quickly--in the authors' experiments one thousand times faster than in a conventional cuvette.
Abstract: We report the use of a liquid-filled hollow-core photonic crystal fiber (PCF) as a highly controlled photochemical reactor. Hollow-core PCFs have several major advantages over conventional sample cells: the sample volume per optical path length is very small (2.8 nL cm(-1) in the fiber used), long optical path lengths are possible as a result of very low intrinsic waveguide loss, and furthermore the light travels in a diffractionless single mode with a constant transverse intensity profile. As a proof of principle, the (very low) quantum yield of the photochemical conversion of vitamin Bp, cyanocobalamin (CNCbl) to hydroxocobalamin ([H(2)OCbl](+)) in aqueous solution was measured for several pH values from 2.5 to 7.5. The dynamics of the actively induced reaction were monitored in real-time by broadband absorption spectroscopy. The PCF nanoreactor required ten thousand times less sample volume compared to conventional techniques. Furthermore. the enhanced sensitivity and optical pump intensity implied that even systems with very small quantum yields can be measured very quickly in our experiments one thousand times faster than in a conventional cuvette.
41 citations
TL;DR: It is demonstrated analytically and numerically that a subwavelength-core dielectric photonic nanowire embedded in a properly designed photonic crystal fiber cladding shows evidence of a previously unknown kind of nonlinearity which acts on solitons so as to considerably reduce their Raman self-frequency shift.
Abstract: We demonstrate analytically and numerically that a subwavelength-core dielectric photonic nanowire embedded in a properly designed photonic crystal fiber cladding shows evidence of a previously unknown kind of nonlinearity (the magnitude of which is strongly dependent on the waveguide parameters) which acts on solitons so as to considerably reduce their Raman self-frequency shift. An explanation of the phenomenon in terms of indirect pulse negative chirping and broadening is given by using the moment method. Our conclusions are supported by detailed numerical simulations.
35 citations
TL;DR: In this paper, the authors provide a full theoretical understanding of the recent observations of Raman two-peak states in solid core photonic crystal fibers based on a "gravity-like" potential approach.
Abstract: We provide a full theoretical understanding of the recent observations of excitation of Raman two-peak states in solid-core photonic crystal fibers Based on a “gravity-like” potential approach we derive simple equations for the “magic” peak power ratio and the temporal separation between pulses forming these two-peak states We develop a model to calculate the magic input power of the input pulse around which the phenomenon can be observed We also predict the existence of exotic multipeak states that strongly violate the perturbative pulse splitting law, and we study their stability and excitation conditions
16 citations
TL;DR: A qualitative and a quantitative explanation of pair formation are provided, and the existence of multipeak states is predicted.
Abstract: In this Letter we give theoretical explanations for the recent observations of the excitation of Raman-shifting pulse pairs in solid-core photonic crystal fibers The formation of these pairs is surprisingly common in the deep anomalous dispersion regime of a large variety of highly nonlinear optical fibers, away from zero group-velocity dispersion points We have developed two different theoretical models, which agree very well in their conclusions A qualitative and a quantitative explanation of pair formation is provided, and the existence of multipeak states is predicted
13 citations
TL;DR: In this paper, the authors investigate the polarization evolution and dispersive properties of the eigenmodes of birefringent media with arbitrarily twisted axes of birrringence, and show that the maximum separation between these curves and the bandwidth of splitting depend on the amplitude of the rocking angle.
Abstract: We investigate the polarization evolution and dispersive properties of the eigenmodes of birefringent media with arbitrarily twisted axes of birefringence. Analytical and numerical methods based on a transfer matrix approach are developed and used to study specifically helically twisted structures and the Bloch modes of periodically twisted media, as represented in particular by structural “rocking” filters inscribed in highly birefringent photonic crystal fibers. The presence of periodically twisted birefringence axes causes the group velocity dispersion curves to separate strongly from each other in the vicinity of the anti-crossing wavelength, where the inter-polarization beat-length equals an integer multiple of the rocking period. The maximum separation between these curves and the bandwidth of the splitting depend on the amplitude of the rocking angle. We also show that suitably designed adiabatic transitions, formed by chirping the rocking period, allow a broadband conversion between a linearly polarized fiber eigenmode and a single Bloch mode of a uniform rocking filter. The widely controllable dispersive properties provided by rocking filters may be useful for manipulating the phase-matching conditions in nonlinear optical processes such as four-wave mixing, supercontinuum generation, and the generation of resonant radiation from solitons.
10 citations
16 May 2010
TL;DR: In this article, the stimulated interpolarization scattering mediated by torsional-radial acoustic resonances in photonic crystal fiber was reported, and the Stokes power conversion was investigated.
Abstract: We report forward stimulated inter-polarization scattering mediated by torsional-radial acoustic resonances in photonic crystal fiber. Orthogonally-polarized co-propagating pump and Stokes waves undergo Stokes power conversion. We also develop analytical theory, which agrees with experimental results.
21 Jun 2010
TL;DR: In this paper, the authors discuss four-wave mixing and resonant radiation in photonic crystal fibers with three zero dispersion wavelengths and find a complex phase-matching landscape that allows multiple frequencies to be generated by both continuous waves and solitons.
Abstract: We discuss four-wave mixing and resonant radiation in photonic crystal fibers with three zero dispersion wavelengths. We find a complex phase-matching landscape that allows multiple frequencies to be generated by both continuous waves and solitons.