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Quantum Electronics and Laser Science Conference, QELS 2001

作者： Musslimani, Z.H. Soljačić, M. Segev, M. Christodoulides, D.N. Department of Applied Mathematics University of Colorado BoulderCO80309-0526 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Physics Department Solid State Institute Technion - Israel Institute of Technology Haifa32 000 Israel Princeton University PrincetonNJ08544 United States Department of Electrical Engineering and Computer Science Lehigh University BethlehemPA18015 United States

ISBN: (纸本)155752663X

Summary form only given. Soliton interactions are universal, displaying features common to all solitons, in spite of the diversity of the physical systems in which solitons are found. The reason for this universality is the fact that solitons can be viewed as modes of their own induced waveguide. The simplest case arises when the self-induced waveguide has only one mode populated, in which case the soliton is a "scalar soliton". In this vein, collisions of single-mode solitons can be viewed intuitively as interactions between guided modes of adjacent waveguides. In this case, the interaction outcome is determined by the relation between the collision angle and the (complementary) critical angle for total internal reflection in each waveguide, θc. Experimentally, collisions between scalar solitons were studied in detail, demonstrating fully-elastic collisions between Kerr solitons, almost-elastic collisions between solitons in saturable nonlinearities interacting at angles above θc and inelastic collisions that yield fusion, fission, annihilation, and spiraling. © 2001 Optical Soc. Of America.

关键词： Solitons

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Constrained optimization over discrete sets via SPSA with application to non-separable resource allocation

Constrained optimization over discrete sets via SPSA with ap...

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Simulation Winter Conference

作者： J.E. Whitney L.I. Solomon S.D. Hill Department of Electrical and Computer Engineering Morgan State University Baltimore MD USA Applied Physics Laboratory Johns Hopkins University Laurel MD USA

This paper presents a version of the simultaneous perturbation stochastic approximation (SPSA) algorithm for optimizing non-separable functions over discrete sets under given constraints. The primary motivation for discrete SPSA is to solve a class of resource allocation problems wherein the goal is to distribute a finite number of discrete resources to finitely many users in such a way as to optimize a specified objective function. The basic algorithm and the application of the algorithm to the optimal resource allocation problem is discussed and simulation, results are presented which illustrate its performance.

关键词： Constraint optimization Resource management Stochastic processes Application software Noise measurement Particle measurements Approximation algorithms Analytical models Performance analysis Algorithm design and analysis

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Timing jitter reduction in diode pumped passively Q-switched laser with composite pumping pulses

Timing jitter reduction in diode pumped passively Q-switched...

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Conference on Lasers and Electro-Optics (CLEO)

作者： J.B. Khurgin Feng Jin G. Solyar Chen-Chia Wmg S. Trivedi Department of Electrical and Computer Engineering Johns Hopkins University-Applied Physics Laboratory Baltimore MD USA Dept. of Electrical and Computer Engineering The Johns Hopkins University Baltimore MD USA Brimrose Corporation of America Baltimore MD USA

Summary form only given. Compact all solid state lasers play a crucial role in the applications such as cost effective reliable laser radars and laser range finders for smart munitions where precision, light-weight, low power consumption, and ruggedness must be achieved simultaneously. For many applications it is desirable to have powerful nanosecond pulses which can be obtained by using Q-switching. Passive Q-switching with saturable absorbers has the advantage of ruggedness, simplicity, and good control of transverse mode. However, saturable absorber suffers from higher intra-cavity losses and, especially, the timing jitter. This is caused by the fluctuations within the system, such as temperature, pump power and wavelength, and the intra-cavity loss, etc. A number of jitter-reduction scheme involving combination of active-passive Q-switching have been proposed, but all of the schemes involved a large number of additional optical elements and the reduction. in jitter was not substantial. We have proposed and demonstrated a simple way to reduce timing jitter of a passively Q-switched laser with composite pumping pulse, which is composed of a long and low-power pulse and a short and high-power pulse. A reduction of more than an order of magnitude in timing jitter has been obtained for a Nd:YAG/Cr/sup 4+/:YAG laser.

关键词： Timing jitter Diodes Laser excitation Pump lasers Laser radar Solid lasers Optical pulses Power lasers Costs Radar applications

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Interactions between two-dimensional composite vector solitons carrying topological charges

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Physical Review E 2001年第6期63卷 066608-066608页

作者： Ziad H. Musslimani Marin Soljačić Mordechai Segev Demetrios N. Christodoulides Department of Applied Mathematics University of Colorado Campus Box 526 Boulder Colorado 80309-0526 Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 Physics Department and Solid State Institute Technion—Israel Institute of Technology 32 000 Haifa IsraelDepartment of Electrical Engineering Princeton University Princeton New Jersey 08544 Department of Electrical Engineering and Computer Science Lehigh University Bethlehem Pennslyvania 18015

We present a comprehensive study of interactions (collisions) between two-dimensional composite vector solitons carrying topological charges in isotropic saturable nonlinear media. We numerically study interactions between such composite solitons for different regimes of collision angle and report numerous effects which are caused solely by the “spin” (topological charge) carried by the second excited mode. The most intriguing phenomenon we find is the delayed-action interaction between interacting composite solitons carrying opposite spins. In this case, two colliding solitons undergo a fusion process and form a metastable bound state that decays after long propagation distances into two or three new solitons. Another noticeable effect is spin-orbit coupling in which angular momentum is being transferred from “spin” to orbital angular momentum. This phenomenon occurs at angles below the critical angle, including the case when the initial soliton trajectories are in parallel to one another and lie in the same plane. Finally, we report on shape transformation of vortex component into a rotating dipole-mode solitons that occurs at large collision angles, i.e., at angles for which scalar solitons of all types simply go through one another unaffected.

关键词： .colliding topological charges bound state nonlinear media saturable composite vector collision angle Soljacˇic Interactions between two-dimensional delayed-action composite solitons carrying

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Applications using a picosecond 14.7 nm x-ray laser 9

Applications using a picosecond 14.7 nm x-ray laser

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Applications of High Field and Short Wavelength Sources, HFSW 2001

作者： Dunn, James Smith, Raymond F. Nilsen, Joseph Shlyaptsev, Vyacheslav N. Filevich, Jorge Rocca, Jorge J. Marconi, Mario C. Lawrence Livermore National Laboratory LivermoreCA94550 United States Dept. of Applied Science University of California Davis-Livermore LivermoreCA94550 United States Dept of Electrical and Computer Engineering Colorado State University Fort CollinsCO80523 United States Physics Department University of Buenos Aires Argentina

We report recent application experiments on the LLNL COMET tabletop facility using the picosecond, 14.7 nm Ni-like Pd x-ray laser. This work includes measurements of a laser- produced plasma density profile with a dif... 详细信息

ISBN: (纸本)1557526877

关键词： Laser produced plasmas

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High sensitivity, low voltage silicon photodetectors compatible with silicon integration

High sensitivity, low voltage silicon photodetectors compati...

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Conference on Lasers and Electro-Optics (CLEO)

作者： J.A. Wahl D. Rogers S. Tiwari Department of Applied and Engineering Physics Cornell University Ithaca NY USA IBM Thomas J. Watson Research Center Yorktown Heights NY USA Department of Electrical and Computer Engineering Cornell University Ithaca NY USA

Summary form only given. The work reports a new high responsivity high sensitivity, high frequency and low voltage photodetector capable of operating at 850 nm and lower wavelengths at multi-GHz frequencies, while providing compatibility with silicon system-on-chip technology. By decoupling the carrier generation process from the carrier collection process, silicon can provide performance characteristics that are either comparable of superior to that achieved from III-V semiconductors. This decoupling is achieved using deep-trench technology based lateral p/sup ++/-polysilicon doped and n/sup ++/-doped junctions that allow for short carrier collection distances while allowing for large absorption depths. Use of poly-silicon-based junctions in silicon allows for low darkcurrent and nearly ideal diodes. Small junction separations and low doping allow low bias and efficient separation of carriers.

关键词： Low voltage Silicon Photodetectors Frequency System-on-a-chip Character generation III-V semiconductor materials Absorption Semiconductor diodes Doping

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Nonlinear robust control for a passive line-of-sight stabilization system

Nonlinear robust control for a passive line-of-sight stabili...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： H. Ambrose Z. Qu R. Johnson Applied Physics Laboratory Johns Hopkins University Laurel MD USA Department of Electrical and Computer Engineering University of Central Florida Orlando FL USA Department of Mechanical and AeroSpace Engineering University of Central Florida Orlando FL USA

In this paper, the technique of model reference robust control (MRRC) is applied to a passive line-of-sight (LOS) stabilization system. The system uses a flywheel as a spinning mass gyroscope to stabilize a two gimbal system against base motion. Due to the gimbal geometry, unwanted dynamic coupling exists in the LOS system. The system is treated as a two input - two output system, and it is then decoupled and controlled using only input/output measurements rather than state feedback. The technique used in this paper for decoupling and control of the LOS system is MRRC which is an extension of model reference control to nonlinear MIMO systems. The technique utilizes bounds of plant parameter uncertainties via controller parameter uncertainties and also input disturbances bounds. Specifically, dynamics of the passive line-of-sight stabilization system are described, followed by a perfect knowledge (MRC) control design and then a nonlinear robust control design.

关键词： Robust control Nonlinear control systems Uncertain systems Flywheels Spinning Gyroscopes Geometry Control systems State feedback MIMO

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Few-cycle-pulse generation and its applications

Few-cycle-pulse generation and its applications

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： F.X. Kartner U. Morgner R. Ell E.P. Ippen J.G. Fujimoto V. Scheuer G. Angelow T. Tschudi Department of Electrical Engineering and Information Technology High-Frequency and Quantum Electronics Laboratory University of Karlsruhe Karlsruhe Germany Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA USA Institute of Applied Physics Technical University of Darmstadt Darmstadt Germany

Sub-two-cycle optical pulses (5 fs) with spectra extending over more than one octave are generated directly from a Kerr-lens modelocked (KLM) Ti:sapphire laser. Applications of this broadband source in optical coheren... 详细信息

关键词： Mirrors Optical pulse generation Bandwidth Nonlinear optics Laser modes Optical resonators Pulse compression methods Space vector pulse width modulation Oscillators Laboratories

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Defects produced by medium energy proton bombardment of MOS devices

Defects produced by medium energy proton bombardment of MOS ...

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European Conference on Radiation and its Effects on Components and Systems (RADECS)

作者： P.M. Lenahan T.D. Mishima J.B. Jumper T.N. Fogarty M. Marrero L. Cruz S. Shojah-Ardalan R. Dwivedi R. Wilkins L.P. Trombetta C. Singh Department of Engineering Science and Mechanics Pennsylvania State University PA USA Department of Physics and Astronomy University of Oklahama Norman OK USA NASA Center for Applied Radiation Research Prairie View A and M University Prairie View TX USA Department of Electrical Engineering and Department of Chemical Science University of Minnesota Minneapolis MN USA Department of Electrical Engineering University of Stanford Stanford CA USA Department of Electrical and Computer Engineering University of Houston Houston TX USA

We report results of very sensitive electron spin resonance (ESR) and electrical measurements made on MOSFETs subjected to medium energy proton bombardment. We observe that the measured defect density levels are similar for both the ESR measurements and electrical measurements. The density of defects is observed to be larger for proton bombarded devices compared to devices irradiated with much larger doses of /sup 60/Co gamma rays. Initial ESR and electrical measurements were made on-site soon after bombardment in the cyclotron.

关键词： Protons MOS devices Telephony Paramagnetic resonance Electric variables measurement NASA Atomic measurements Extraterrestrial measurements USA Councils Density measurement

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Interpolation formula between very low and intermediate-to-high damping Kramers escape rates for single-domain ferromagnetic particles

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Physical Review E 2001年第2期63卷 021102-021102页

作者： P. M. Déjardin D. S. F. Crothers W. T. Coffey D. J. McCarthy Department of Applied Mathematics and Theoretical Physics David Bates Building The Queen’s University of Belfast Belfast BT7 1NN Northern Ireland United Kingdom Department of Electronics and Electrical Engineering Trinity College Dublin 2 Ireland School of Mathematics Statistics and Computer Science Dublin Institute of Technology Kevin Street Dublin 8 Ireland

It is shown that the Mel’nikov-Meshkov formalism for bridging the very low damping (VLD) and intermediate-to-high damping (IHD) Kramers escape rates as a function of the dissipation parameter for mechanical particles may be extended to the rotational Brownian motion of magnetic dipole moments of single-domain ferromagnetic particles in nonaxially symmetric potentials of the magnetocrystalline anisotropy so that both regimes of damping occur. The procedure is illustrated by considering the particular nonaxially symmetric problem of superparamagnetic particles possessing uniaxial anisotropy subject to an external uniform field applied at an angle to the easy axis of magnetization. Here the Mel’nikov-Meshkov treatment is found to be in good agreement with an exact calculation of the smallest eigenvalue of Brown’s Fokker-Planck equation, provided the external field is large enough to ensure significant departure from axial symmetry, so that the VLD and IHD formulas for escape rates of magnetic dipoles for nonaxially symmetric potentials are valid.

关键词： Ferromagnetic materials

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