Philip St J Russell

Publications (30)101.96 Total impact

• Article: Long-distance laser propulsion and deformation- monitoring of cells in optofluidic photonic crystal fiber.

  Sarah Unterkofler, Martin K Garbos, Tijmen G Euser, Philip St J Russell
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  ABSTRACT: We introduce a unique method for laser-propelling individual cells over distances of 10s of cm through stationary liquid in a microfluidic channel. This is achieved by using liquid-filled hollow-core photonic crystal fiber (HC-PCF). HC-PCF provides low-loss light guidance in a well-defined single mode, resulting in highly uniform optical trapping and propulsive forces in the core which at the same time acts as a microfluidic channel. Cells are trapped laterally at the center of the core, typically several microns away from the glass interface, which eliminates adherence effects and external perturbations. During propagation, the velocity of the cells is conveniently monitored using a non-imaging Doppler velocimetry technique. Dynamic changes in velocity at constant optical powers up to 350 mW indicate stress-induced changes in the shape of the cells, which is confirmed by bright-field microscopy. Our results suggest that HC-PCF will be useful as a new tool for the study of single-cell biomechanics. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
  Journal of Biophotonics 12/2012; · 4.34 Impact Factor
• Article: Polarisation-resolved near-field mapping of a coupled gold nanowire array.

  Patrick Uebel, Markus A Schmidt, Howard W Lee, Philip St J Russell
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  ABSTRACT: We report direct observation of the 2D transverse near-field intensity and polarisation distribution of surface plasmon polaritons guided on metal nanowires. Quadrupolar modes are excited on an array of coupled nanowires arranged around the central glass core in a photonic crystal fibre, with lobes whose orientation depends on the polarisation state of the launched core light. The radial electric field is resolved using a polarization sensitive near-field probe in light-collection mode.
  Optics Express 12/2012; 20(27):28409-17. · 3.59 Impact Factor
• Article: Efficient optical pumping and high optical depth in a hollow-core photonic-crystal fibre for a broadband quantum memory

  Michael R. Sprague, Duncan G. England, Amir Abdolvand, Joshua Nunn, Xian-Min Jin, W. Steven Kolthammer, Marco Barbieri, Bruno Rigal, Patrick S. Michelberger, Tessa F. M. Champion, Philip St. J. Russell, Ian A. Walmsley
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  ABSTRACT: The generation of large multiphoton quantum states - for applications in computing, metrology, and simulation - requires a network of high-efficiency quantum memories capable of storing broadband pulses. Integrating these memories into a fibre offers a number of advantages towards realising this goal: strong light-matter coupling at low powers, simplified alignment, and compatibility with existing photonic architectures. Here, we introduce a large-core kagome-structured hollow-core fibre as a suitable platform for an integrated fibre-based quantum memory with a warm atomic vapour. We demonstrate, for the first time, efficient optical pumping in a hollow-core photonic-crystal fibre with a warm atomic vapour, where (90 $\pm$ 1)% of atoms are prepared in the ground state. We measure high optical depths (3$\times 10^{4}$) and, also, narrow homogeneous linewidths that do not exhibit significant transit-time broadening. Our results establish that kagome fibres are suitable for implementing a broadband, room-temperature quantum memory.
  12/2012;
• Article: Kagome hollow-core photonic crystal fiber probe for Raman spectroscopy.

  Petru Ghenuche, Silke Rammler, Nicolas Y Joly, Michael Scharrer, Michael Frosz, Jérôme Wenger, Philip St J Russell, Hervé Rigneault
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  ABSTRACT: We demonstrate the use of a large-pitch Kagome-lattice hollow-core photonic crystal fiber probe for Raman spectroscopy. The large transmission bandwidth of the fiber enables both the excitation and Raman beams to be transmitted through the same fiber. As the excitation beam is mainly transmitted through air inside the hollow core, the silica luminescence background is reduced by over 2 orders of magnitude as compared to standard silica fiber probes, removing the need for fiber background subtraction.
  Optics Letters 11/2012; 37(21):4371-3. · 3.40 Impact Factor
• Source

  Available from: John Colin Travers

  Article: Plasma-induced asymmetric self-phase modulation and universalmodulational instability in gas-filled hollow-core photonic crystal fibers

  Mohammed F. Saleh, Wonkeun Chang, John C. Travers, Philip St. J. Russell, Fabio Biancalana
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  ABSTRACT: We study theoretically the propagation of relatively long pulses with ionizing intensities in a hollow-core photonic crystal fiber filled with a Raman-inactive gas. Due to photoionization, previously unknown types of asymmetric self-phase modulation and `universal' modulational instabilities existing in both normal and anomalous dispersion regions appear. We also show that it is possible to spontaneously generate a plasma-induced continuum of blueshifting solitons, opening up new possibilities for pushing supercontinuum generation towards shorter and shorter wavelengths.
  Physical Review Letters 09/2012; 109:113902. · 7.37 Impact Factor
• Article: Thermo-modulational interband susceptibility and ultrafast temporal dynamics in nonlinear gold-based plasmonic devices

  Andrea Marini, Matteo Conforti, Giuseppe Della Valle, Ho Wai Lee, Truong X. Tran, Wonkeun Chang, Markus A. Schmidt, Stefano Longhi, Philip St. J. Russell, Fabio Biancalana
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  ABSTRACT: Starting from first principles, we theoretically model the nonlinear temporal dynamics of gold-based plasmonic devices resulting from the heating of their metallic components. At optical frequencies, the gold susceptibility is determined by the interband transitions around the X,L points in the first Brillouin zone and thermo-modulational effects ensue from Fermi smearing of the electronic energy distribution in the conduction band. As a consequence of light-induced heating of the conduction electrons, the optical susceptibility becomes nonlinear. In this paper we describe, for the first time to our knowledge, the effects of the thermo-modulational nonlinearity of gold on the propagation of surface plasmon polaritons guided on gold nanowires. We introduce a novel nonlinear Schroedinger-like equation to describe pulse propagation in such nanowires, and we predict the appearance an intense spectral red-shift caused by the delayed thermal response.
  08/2012;
• Article: Photonic crystal fibre as an optofluidic reactor for the measurement of photochemical kinetics with sub-picomole sensitivity.

  Gareth O S Williams, Jocelyn S Y Chen, Tijmen G Euser, Philip St J Russell, Anita C Jones
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  ABSTRACT: Photonic crystal fibre constitutes an optofluidic system in which light can be efficiently coupled into a solution-phase sample, contained within the hollow core of the fibre, over long path-lengths. This provides an ideal arrangement for the highly sensitive monitoring of photochemical reactions by absorption spectroscopy. We report here the use of UV/vis spectroscopy to measure the kinetics of the photochemical and thermal cis-trans isomerisation of sub-picomole samples of two azo dyes within the 19-μm diameter core of a photonic crystal fibre, over a path length of 30 cm. Photoisomerisation quantum yields are the first reported for "push-pull" azobenzenes in solution at room temperature; such measurements are challenging because of the fast thermal isomerisation process. Rate constants obtained for thermal isomerisation are in excellent agreement with those established previously in conventional cuvette-based measurements. The high sensitivity afforded by this intra-fibre method enables measurements in solvents in which the dyes are too insoluble to permit conventional cuvette-based measurements. The results presented demonstrate the potential of photonic crystal fibres as optofluidic elements in lab-on-a-chip devices for photochemical applications.
  Lab on a Chip 07/2012; 12(18):3356-61. · 5.67 Impact Factor
• Article: Ultra-low concentration monitoring of catalytic reactions in photonic crystal fiber.

  Ana M Cubillas, Matthias Schmidt, Michael Scharrer, Tijmen G Euser, Bastian J M Etzold, Nicola Taccardi, Peter Wasserscheid, Philip St J Russell
  Chemistry 02/2012; 18(6):1586-90. · 5.93 Impact Factor
• Source

  Available from: John Colin Travers

  Article: Theory of photoionization-induced blueshift of ultrashort solitons in gas-filled hollow-core photonic crystal fibers.

  Mohammed F Saleh, Wonkeun Chang, Philipp Hölzer, Alexander Nazarkin, John C Travers, Nicolas Y Joly, Philip St J Russell, Fabio Biancalana
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  ABSTRACT: We show theoretically that the photoionization process in a hollow-core photonic crystal fiber filled with a Raman-inactive noble gas leads to a constant acceleration of solitons in the time domain with a continuous shift to higher frequencies, limited only by ionization loss. This phenomenon is opposite to the well-known Raman self-frequency redshift of solitons in solid-core glass fibers. We also predict the existence of unconventional long-range nonlocal soliton interactions leading to spectral and temporal soliton clustering. Furthermore, if the core is filled with a Raman-active molecular gas, spectral transformations between redshifted, blueshifted, and stabilized solitons can take place in the same fiber.
  Physical Review Letters 11/2011; 107(20):203902. · 7.37 Impact Factor
• Article: Optomechanical self-channelling of light in a suspended planar dual-nanoweb waveguide

  Anna Butsch, Claudio Conti, Fabio Biancalana, Philip St. J. Russell
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  ABSTRACT: It is shown that optomechanical forces can cause nonlinear self-channelling of light in a planar dual-slab waveguide. A system of two parallel silica nanowebs, spaced ~100 nm and supported inside a fibre capillary, is studied theoretically and an iterative scheme developed to analyse its nonlinear optomechanical properties. Steady-state field distributions and mechanical deformation profiles are obtained, demonstrating that self-channelling is possible in realistic structures at launched powers as low as a few mW. The differential optical nonlinearity of the self-channelled mode can be as much as ten million times higher than the corresponding electronic Kerr nonlinearity. It is also intrinsically broadband, does not utilize resonant effects, can be viewed as a consequence of the extreme nonlocality of the mechanical response, and in fact is a notable example of a so-called "accessible" soliton.
  08/2011;
• Article: Bandgap guidance in hybrid chalcogenide-silica photonic crystal fibers.

  Nicolai Granzow, Patrick Uebel, Markus A Schmidt, Andrey S Tverjanovich, Lothar Wondraczek, Philip St J Russell
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  ABSTRACT: We report a hybrid chalcogenide-silica photonic crystal fiber made by pressure-assisted melt-filling of molten glass. Photonic bandgap guidance is obtained at a silica core placed centrally in a hexagonal array of continuous centimeters-long chalcogenide strands with diameters of 1.45 μm. In the passbands of the cladding, when the transmission through the silica core is very weak, the chalcogenide strands light up with distinct modal patterns corresponding to Mie resonances. In the spectral regions between these passbands, strong bandgap guidance is observed, where the silica core transmission loss is 60 dB/cm lower. The pressure-assisted fabrication approach opens up new ways of integrating sophisticated glass-based devices into optical fiber circuitry with potential applications in supercontinuum generation, magneto-optics, wavelength selective devices, and rare-earth-doped amplifiers with high gain per unit length.
  Optics Letters 07/2011; 36(13):2432-4. · 3.40 Impact Factor
• Source

  Available from: John Colin Travers

  Article: Soliton self-frequency blue-shift in gas-filled hollow-core photonic crystal fibers

  Mohammed F. Saleh, Wonkeun Chang, Philipp Hoelzer, Alexander Nazarkin, John C. Travers, Nicolas Y. Joly, Philip St J Russell, Fabio Biancalana
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  ABSTRACT: We show theoretically that the photoionization process in a hollow-core photonic crystal fiber filled with a Raman-inactive noble gas leads to a constant acceleration of solitons in the time domain with a continuous shift to higher frequencies, limited only by ionization loss. This phenomenon is opposite to the well-known Raman self-frequency red-shift of solitons in solid-core glass fibers. We also predict the existence of unconventional long-range non-local soliton interactions leading to spectral and temporal soliton clustering. Furthermore, if the core is filled with a Raman-active molecular gas, spectral transformations between red-shifted, blue-shifted and stabilized solitons can take place in the same fiber.
  06/2011;
• Article: Complex Faraday rotation in microstructured magneto-optical fiber waveguides.

  Markus A Schmidt, Lothar Wondraczek, Ho W Lee, Nicolai Granzow, Ning Da, Philip St J Russell
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  ABSTRACT: Magneto-optical glasses are of considerable current interest, primarily for applications in fiber circuitry, optical isolation, all-optical diodes, optical switching and modulation. While the benchmark materials are still crystalline, glasses offer a variety of unique advantages, such as very high rare-earth and heavy-metal solubility and, in principle, the possibility of being produced in fiber form. In comparison to conventional fiber-drawing processes, pressure-assisted melt-filling of microcapillaries or photonic crystal fibers with magneto-optical glasses offers an alternative route to creating complex waveguide architectures from unusual combinations of glasses. For instance, strongly diamagnetic tellurite or chalcogenide glasses with high refractive index can be combined with silica in an all-solid, microstructured waveguide. This promises the implementation of as-yet-unsuitable but strongly active glass candidates as fiber waveguides, for example in photonic crystal fibers.
  Advanced Materials 06/2011; 23(22-23):2681-8. · 13.88 Impact Factor
• Article: An azimuthally polarizing photonic crystal fibre with a central gold nanowire

  Patrick Uebel, Markus A Schmidt, Michael Scharrer, Philip St J Russell
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  ABSTRACT: An air–silica photonic crystal fibre with a gold nanowire at core centre is shown to support a low-loss azimuthally polarized mode. Since all the other modes have very high attenuation, the fibre effectively supports only this mode, acting as a single-polarization fibre with an extinction ratio >20 dB cm−1 over a broad range of wavelengths (550–1650 nm in the device reported). It can be used as an effective azimuthal mode filter.
  New Journal of Physics 06/2011; 13(6):063016. · 4.18 Impact Factor
• Source

  Available from: arxiv.org

  Article: Highly noninstantaneous solitons in liquid-core photonic crystal fibers.

  Claudio Conti, Markus A Schmidt, Philip St J Russell, Fabio Biancalana
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  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 Schrödinger equation. The physical relevance of these novel solitons is discussed.
  Physical Review Letters 12/2010; 105(26):263902. · 7.37 Impact Factor
• Source

  Available from: ArXiv

  Article: Linearons: highly non-instantaneous solitons in liquid-core photonic crystal fibers

  Claudio Conti, Markus Schmidt, Philip St J Russell, Fabio Biancalana
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  ABSTRACT: The nonlinear propagation of light pulses in liquid-filled photonic crystal fibers is considered. Due to 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 Schroedinger equation. The physical relevance of these novel solitary structures, which may have a broad range of applications, is discussed and supported by detailed numerical simulations. Comment: 4 pages, 3 figures
  10/2010;
• Source

  Available from: arxiv.org

  Article: Emergence of geometrical optical nonlinearities in photonic crystal fiber nanowires.

  Fabio Biancalana, Truong X Tran, Sebastian Stark, Markus A Schmidt, Philip St J Russell
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  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.
  Physical Review Letters 08/2010; 105(9):093904. · 7.37 Impact Factor
• Source

  Available from: mpg.de

  Article: Understanding Raman-shifting multipeak states in photonic crystal fibers: two convergent approaches.

  Alexander Hause, Truong X Tran, Fabio Biancalana, Alexander Podlipensky, Philip St J Russell, Fedor Mitschke
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  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.
  Optics Letters 07/2010; 35(13):2167-9. · 3.40 Impact Factor
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  Available from: ArXiv

  Article: Theory of Raman multipeak states in solid-core photonic crystal fibers

  Truong X Tran, Alexander Podlipenksy, Philip St J Russell, Fabio Biancalana
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  ABSTRACT: Pulse splitting is a crucial and common process in nonlinear fiber optics. When an intense laser pulse is launched into a highly nonlinear fiber, a stream of fundamental solitons is generated, their temporal separations increasing during propagation. This is due to the onset of a variety of perturbations, including higher-order dispersion and the Raman effect. Recently, it has been experimentally observed that the well-known law determining the amplitudes and the temporal widths of each soliton, however, breaks down due to the unexpected formation of metastable 2-peak localised states with constant temporal separation between the two maxima. In the vicinity of certain 'magic' input powers the formation of 2-peak states is quite common in many types of highly nonlinear photonic crystal fibers. In this study, we provide a full theoretical understanding of the above recent observations. 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 2-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.
  05/2010;
• Source

  Available from: ArXiv

  Article: Multiple hydrodynamical shocks induced by Raman effect in photonic crystal fibres

  Claudio Conti, Sebastian Stark, Philip St J Russell, Fabio Biancalana
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  ABSTRACT: We theoretically predict the occurrence of multiple hydrodynamical-like shock phenomena in the propagation of ultrashort intense pulses in a suitably engineered photonic crystal fiber. The shocks are due to the Raman effect, which acts as a nonlocal term favoring their generation in the focusing regime. It is shown that the problem is mapped to shock formation in the presence of a slope and a gravity-like potential. The signature of multiple shocks in XFROG signals is unveiled.
  04/2010;