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- Nonlinear optics (4)
- Solitons and modulation theory (2)
- Combustion theory (1)
- Fused silica (1)
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- Liquid crystal; Soliton; Soliton dipole; Nematicon; Modulation theory (1)
- Liquids and polymers Mathematical physics Computational physics Optics (1)
- Modified Korteweg-de Vries equation; Soliton; Undular bore; Modulation theory; Initial-boundary value problem (1)
- Optogalvanic effect (1)
- Plasma generation (1)
- Quantum optics and lasers (1)
- Reaction–diffusion–convection equations; Cubic autocatalysis; Applied electric field; Ionic migration; Singularity theory; Hopf bifurcations; Semi-analytical solutions (1)
- Soft matter (1)
- Ultrafast pulse propagation (1)
Articles 1 - 11 of 11
Full-Text Articles in Physics
Sub-Micron Parallel Laser Direct-Write, Christina Othon, Arnoldo Laracuente, H Ladoucuer, Bradley Ringeisen
Sub-Micron Parallel Laser Direct-Write, Christina Othon, Arnoldo Laracuente, H Ladoucuer, Bradley Ringeisen
Christina M Othon
We have developed a modified laser induced forward transfer (LIFT) technique which allows for the parallel deposition of hundreds of sub-micron features. The approach utilizes a self-assembled monolayer of monodisperse polystyrene microspheres as the focusing element. A monolayer of close-packed microspheres is formed on top of an ultra-thin quartz support (25 m thick), and a metallic thin film is then deposited on the underside of the quartz. This approach is different from previous parallel microsphere-assisted LIFT experiments that required the deposition of metal directly onto the surface of the periodic microsphere structure. For this study, an 800 nm, 130 fs …
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
Naveed K. Piracha
We report on the temporal evolution of the optogalvanic signals in neon using a commercial hollow cathode lamp in conjunction with a Nd:YAG pumped dye laser system. We have recorded transitions excited from each of the neon 1s states over a range of discharge current to investigate the dominant physical processes responsible for the optogalvanic effect in neon discharges. The decay rates associated with the four 1s levels have been obtained using a mathematical rate equation model. A linear relationship between the decay rates and the discharge current has been found and the effective lifetimes and the electron collisional rate …
Simulation And Analysis Of Ultrafast-Laser-Pulse-Induced Plasma Generation In Fused Silica, Jeremy Gulley, Sebastian Winkler, W. M. Dennis
Simulation And Analysis Of Ultrafast-Laser-Pulse-Induced Plasma Generation In Fused Silica, Jeremy Gulley, Sebastian Winkler, W. M. Dennis
Jeremy R. Gulley
Recent experiments on optical damage by ultrashort laser pulses have demonstrated that the temporal pulse shape can dramatically influence plasma generation in fused silica. We use a modified 3+1D nonlinear Schrödinger equation for the pulse propagation coupled to a rate equation for the plasma density in the dielectric material to simulate pulse propagation and plasma formation in fused silica. We use these simulations to analyze the influence of pulse shape and beam geometry on the formation of the electron plasma and hence modification in the bulk material. In particular, we simulate the effect of pulses reconstructed from experimental data. It …
Single-Cell Printing To Form Three-Dimensional Lines Of Olfactory Ensheathing Cells, Christina Othon, Xingjia Wu, Juanita Anders, Bradley Ringeisen
Single-Cell Printing To Form Three-Dimensional Lines Of Olfactory Ensheathing Cells, Christina Othon, Xingjia Wu, Juanita Anders, Bradley Ringeisen
Christina M Othon
Biological laser printing (BioLP™) is a unique tool capable of printing high resolution two- and three-dimensional patterns of living mammalian cells, with greater than 95% viability. These results have been extended to primary cultured olfactory ensheathing cells (OECs), harvested from adult Sprague-Dawley rats. OECs have been found to provide stimulating environments for neurite outgrowth in spinal cord injury models. BioLP is unique in that small load volumes (~µLs) are required to achieve printing, enabling low numbers of OECs to be harvested, concentrated and printed. BioLP was used to form several 8 mm lines of OECs throughout a multilayer hydrogel scaffold. …
Evolution Of Higher-Order Gray Hirota Solitary Waves, Tim Marchant
Evolution Of Higher-Order Gray Hirota Solitary Waves, Tim Marchant
Tim Marchant
The defocusing Hirota equation has dark and gray soliton solutions which are stable on a background of periodic waves of constant amplitude. In this paper, gray solitary wave evolution for a higher-order defocusing Hirota equation is examined. A direct analysis is used to identify families of higher-order gray Hirota solitary waves, which are embedded for certain parameter values. Soliton perturbation theory is used to detmine the detailed behavior of an evolving higher-order gray Hirota solitary wave. An integral expression for the first-order correction to the wave is found and analytical expressions for the steady-state and transient components of the solitary …
Mathematical Modelling Of Nematicons And Their Interactions, Prof. Tim Marchant
Mathematical Modelling Of Nematicons And Their Interactions, Prof. Tim Marchant
Tim Marchant
The mathematical modelling of guided wave (nematicon) propagation in liquid crystals is considered. Model equations are derived based on suitable trial functions in an averaged Lagrangian. These equations are used to model nematicon interactions.
Undular Bores And The Initial-Boundary Value Problem For The Modified Korteweg-De Vries Equation, Tim Marchant
Undular Bores And The Initial-Boundary Value Problem For The Modified Korteweg-De Vries Equation, Tim Marchant
Tim Marchant
Two types of analytical undular bore solutions, of the initial value problem for the modified Korteweg-de Vries (mKdV), are found. The first, an undular bore composed of cnoidal waves, is qualitatively similar to the bore found for the KdV equation, with solitons occurring at the leading edge and small amplitude linear waves occurring at the trailing edge. The second, a newly identified type of undular bore, consists of finite amplitude sinusiodal waves, which have a rational form. At the leading edge is the mKdV algebraic soliton, while, again, small amplitude linear waves occur at the trailing edge. The initial-boundary value …
Collisionless Shock Resolution In Nematic Liquid Crystals, Tim Marchant
Collisionless Shock Resolution In Nematic Liquid Crystals, Tim Marchant
Tim Marchant
The diffractive resolution on a collisionless shock formed along the spatial profile of a beam in a nematic liquid crystal is considered, this material being an example of a self-focusing, nonlocal medium. It is found that the shock is resolved through the formation of an undular bore structure which persists for experimentally relevant propagation distances due to nonlocality delaying the onset of modulational instability. Both 1+1 and 2+1 dimensional bores with circular symmetry are considered (termed line and circular bores, respectively). A semianalytical solution is developed for the line undular bore, approximating it as a train of uniform solitary waves. …
Semi-Analytical Solutions For A Gray-Scott Reaction-Diffusion Cell With An Applied Electric Field, Tim Marchant
Semi-Analytical Solutions For A Gray-Scott Reaction-Diffusion Cell With An Applied Electric Field, Tim Marchant
Tim Marchant
An ionic version of the Gray–Scott chemical reaction scheme is considered in a reaction–diffusion cell, with an applied electric field, which causes migration of the reactant and autocatalyst in a preferred direction. The Galerkin method is used to reduce the governing partial differential equations to an approximate model consisting of ordinary differential equations. This is accomplished by approximating the spatial structure of the reactant and autocatalyst concentrations. Bifurcation analysis of the semi-analytical model is performed by using singularity theory to analyse the static multiplicity and a stability analysis to determine the dynamic multiplicity. The application of the electric field causes …
Nonlocal Validity Of An Asymptotic One-Dimensional Nematicon Solution, Tim Marchant
Nonlocal Validity Of An Asymptotic One-Dimensional Nematicon Solution, Tim Marchant
Tim Marchant
The propagation of coherent, polarized light in a nematic liquid crystal, governed by the nematicon equations, is considered. It is found that in the special case of 1 + 1 dimensions and the highly nonlocal limit, the nematicon equations have an asymptotic bulk solitary wave solution, termed a nematicon, which is given in terms of Bessel functions. This asymptotic solution gives both the ground state and the symmetric and antisymmetric excited states, which have multiple peaks. Numerical simulations of nematicon evolution, for parameters corresponding to experimental scenarios, are presented. It is found, for experimentally reasonable parameter choices, that the validity …
Dipole Soliton Formation In A Nematic Liquid Crystal In The Non-Local Limit, Tim Marchant
Dipole Soliton Formation In A Nematic Liquid Crystal In The Non-Local Limit, Tim Marchant
Tim Marchant
The interaction of two symmetric solitary waves, termed nematicons, in a liquid crystal is considered in the limit of nonlocal response of the liquid crystal. This nonlocal limit is the applicable limit for most experimentally available liquid crystals. In this nonlocal limit, two separate cases for the initial separation of the nematicons are considered, these being large and small separation. Both spinning and nonspinning nematicons are considered. It is found that in the case of large initial separation, the nematicons can form a spinning or nonspinning bound state with a finite steady separation, this being called a nematicon dipole, when …