A5021359021- Nonlinear Waves and Solitons
- Nonlinear Photonic Systems
- Ocean Waves and Remote Sensing
- Advanced Mathematical Physics Problems
- Quantum chaos and dynamical systems
- Laser Design and Applications
- Fluid Dynamics and Turbulent Flows
- Solid State Laser Technologies
- Fluid Dynamics Simulations and Interactions
- Semiconductor Lasers and Optical Devices
- Nonlinear Dynamics and Pattern Formation
- Photonic and Optical Devices
- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Coastal and Marine Dynamics
- Semiconductor Quantum Structures and Devices
- Wave and Wind Energy Systems
- Numerical methods for differential equations
- Oceanographic and Atmospheric Processes
- Photorefractive and Nonlinear Optics
- Computational Fluid Dynamics and Aerodynamics
- Advanced Differential Equations and Dynamical Systems
- Laser-Matter Interactions and Applications
- Geophysics and Sensor Technology
- Differential Equations and Numerical Methods
University of Surrey
2014-2024
Amalgamated Sugar (United States)
2017
University of Warwick
1990-1994
Utrecht University
1992-1994
Université Côte d'Azur
1994
Mathematical Institute of the Slovak Academy of Sciences
1990-1993
AT&T (United States)
1984-1992
University of Oxford
1990
Worcester Polytechnic Institute
1987-1990
University of Wisconsin–Madison
1985-1987
A Hamiltonian structure is presented, which generalizes classical structure, by assigning a distinct symplectic operator for each unbounded space direction and time, of evolution equation on one or more dimensions. This generalization, called multi-symplectic structures, shown to be natural dispersive wave propagation problems. Application the abstract properties structures framework leads new variational principle space-time periodic states reminiscent invariant tori, geometric...
The paper provides an introduction and survey of conservative discretization methods for Hamiltonian partial differential equations. emphasis is on variational, symplectic multi-symplectic methods. derivation as well some their fundamental geometric properties are discussed. Basic principles illustrated by means examples from wave fluid dynamics.
cw laser action is obtained on two lines in methyl fluoride, three vinyl chloride, and 23 alcohol by optically pumping the gases with various of CO2 laser. The wavelengths range from 70 to 700 μm.
Using two step-tunable CO2 lasers, we have observed phase-matched generation of frequencies 70 <ν<110 cm−1 by nonlinear mixing in a birefringent ternary semiconductor, ZnGeP2. An power ∼1.7 μW at 83.37 gave signal-to-noise ratio ∼1000 with Ge:Ga detector. In combination tunable optical this technique should yield source submillimeter wave radiation for high-resolution spectroscopy.
In a far infrared molecular laser the traditional pierced output mirror has been replaced by an interference filter, consisting of two metal mesh reflector grids. By adjusting spacing between parallel grids, reflectance filter can be varied. Theory and experiment this variable are presented. It allows convenient optimization coupling conditions for maximum power output. contrast to hole coupling, provides uniform over entire cross section reflector. This reduces diffraction losses improves...
Compact cw single-mode CO2 : He N2 lasers with a 1-mm-diam dielectric waveguide discharge tube have exhibited gains of up to 37 dB/m, volumetric power outputs 15 W/cm3, and saturation parameters 3600 W/cm2 coolant temperature −70°C. With tap water cooling at 20°C the corresponding values were 24 9.5 2100 W/cm2. All these are substantially larger than those obtained conventional lasers. A 12.5-cm-long an active volume 0.096 cm3 gave output 1.4 W −70°C 0.9 temperature.
A microwave nonlinear susceptibility analogous to the optical and electro-optical susceptibilities is investigated in a number of acentric ferroelectric semiconductor crystals. Contributions from ionic nonlinearities result enormously larger coefficients some materials than any known for or effects. An interpretation presented terms relationship between electronic linear susceptibilities.
A room-temperature bulk GaAs mixer is used to mix frequencies of pairs cw vibrational-rotational C${\mathrm{O}}_{2}$ laser lines, each stabilized line center. The beat frequencies, in the millimeter-wave region 50-80 GHz, are measured for 37 transitions better than 1 MHz. deduced rotational constants relevant vibrational levels (00\ifmmode^\circ\else\textdegree\fi{}1, 10\ifmmode^\circ\else\textdegree\fi{}0, 02\ifmmode^\circ\else\textdegree\fi{}0) 25 200 times more accurate best previous...
The frequency mixing of infrared signals with visible laser light in nonlinear crystals (here referred to as up-conversion) has been suggested a possible means detecting by use sensitive and fast wavelength detectors. Preliminary experiments are reported the up-conversion CW 10.6 μ CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> phase-matched difference HgS 0.6328 μ, He-Ne produce 0.6729 which is detected an <tex...
cw laser action at 81.5 and 263.4 μm, corresponding to a rotational transition an inversion in the v2 state of NH3, has been obtained by optically pumping gas with N2O laser.
Mode locking of a transversely excited atmospheric-pressure CO2 laser has been achieved through the use germanium acousto-optic modulator. Subnanosecond pulse widths and peak powers in excess 1 MW have obtained.
The film flow down an inclined plane has several features that make it interesting prototype for studying transition in a shear flow: the basic parallel state is exact explicit solution of Navier–Stokes equations; experimentally observed this shows many properties common with boundary-layer transition; and free surface, leading to more than one class modes. In paper, unstable wavepackets – associated full equations viscous free-surface boundary conditions are analysed by using formalism...
Action, symplecticity, signature and complex instability are fundamental concepts in Hamiltonian dynamics which can be characterized terms of the symplectic structure. In this paper, PDEs on unbounded domains a multisymplectic structure where distinct differential two–form is assigned to each space direction time. This leads new geometric formulation conservation wave action for linear nonlinear PDEs, and, via Stokes's theorem, law symplecticity. Each used define invariant eigenspace normal...
This paper and Part 2 report various new insights into the classic Kelvin–Helmholtz problem which models instability of a plane vortex sheet complicated motions arising therefrom. The full nonlinear version hydrodynamic is treated, with allowance for gravity surface tension, account deals in precise fashion several inherently peculiar properties mathematical model. main achievement paper, presented §3, to demonstrate that admits canonical Hamiltonian formulation, represents novel variational...
Using a multiplexer and demultiplexer built from discrete GaAs FET's, directly modulated distributed feedback laser, low capacitance avalanche photodiode receiver, we have achieved transmission at 4 Gbit/s over 103 km of single-mode optical fiber 1.54 μm.