Allan Struthers

Second-harmonic pulse compression in the soliton regime.

Analytical soliton solutions of the three-wave interaction equations are shown to exhibit high power conversion for a range of nonlinear materials with no satellite peaks and energy conversion close to 100%. Related numerical solutions that yield power conversion up to 10 times those of the initial waves with less than 3% energy in the small satellite peaks and high-energy efficiency are exhibited for KDP crystals; substantial compression of the fundamental pulses is observed in this case.

Laser trapping of microscopic particles for undergraduate experiments

We present detailed instructions for constructing and operating an optical trap using a hollow core fiber and two-laser beams. The trap is stable, confining 100-nm to 10-μm particles of a variety of materials for hours of leisurely observation. The trap operates at room temperature and atmospheric pressure, costs less than

Three-wave soliton interaction of ultrashort pulses in quadratic media

1400, and requires no machining. The hollow fiber provides automatic relative beam alignment and shields trapped particles from the ambient convective flow. An experiment and analysis of the Mie scattering from the trapped particle is outlined. A list of other interesting experiments based on the trap is provided.

Recursive integral method for transmission eigenvalues

Analytical soliton solutions of the nonlinear three-wave-interaction (TWI) equations are generalized to include phase mismatch Δk. These solutions describe the interaction of so-called TWI solitons. The TWI-soliton and near-TWI-soliton regimes show high-second-harmonic and sum-frequency compression with insignificant satellite pulses for a wide range of nonlinear crystals. Analysis of the solutions shows large time and phase shifts of the fundamentals after the interaction. These shifts are fairly insensitive to the phase mismatch (the dependence is second order in Δk), which may make them useful in all-optical switching devices.

Measuring evaporation rates of laser-trapped droplets by use of fluorescent morphology-dependent resonances

The transmission eigenvalue problem arose in the inverse scattering theory for inhomogeneous media and has important applications in a variety of inverse problems for target identification and nondestructive testing. The problem is numerically challenging because of the nonself-adjointness and complicated spectrum. In this talk, we introduce a novel recursive contour integral method using the spectrum projection. The method can compute both real and complex eigenvalues and does not require any a priori information. Numerical examples show that the method is effective and robust.

Parametric amplification of chirped pulses in the presence of a large phase mismatch

Morphology-dependent resonances (MDRs) are used to measure accurately the evaporation rates of laser-trapped 1- to 2-mum droplets of ethylene glycol. Droplets containing 3 x 10(-5) M Rhodamine-590 laser dye are optically trapped in a 20-mum hollow fiber by two counterpropagating 150-mW, 800-nm laser beams. A weaker 532-nm laser excites the dye, and fluorescence emission is observed near 560 nm as the droplet evaporates. A complete series of first-order TE and TM MDRs dominates the fluorescent output. MDR mode identification sizes the droplets and provides accurate evaporation rates. We verify the automated MDR mode identification by counting fringes in a videotape of the experiment. The longitudinal spring constant of the trap, measured by analysis of the videotaped motion of droplets perturbed from the trap center, provides independent verification of the lasers intensity within the trap.

Soliton pulse compression in the theory of optical parametric amplification

Analytical soliton solutions of parametric amplification with arbitrary phase and amplitude modulation of the input signal pulse are obtained for nonzero phase mismatch. The output pulses suffer a frequency shift proportional to the phase mismatch and can be transform limited even for a chirped seed. This property allows us to obtain broadly tunable radiation by optical parametric amplification of a strongly chirped seed wave with a fixed central frequency.

Real-Time Signal Processing of Massive Sensor Arrays via a Parallel Fast Converging SVD Algorithm: Latency, Throughput, and Resource Analysis

Using inverse scattering transform theory, we obtain new analytical expressions describing the process of parametric amplification by ultrashort pulses. We show that the result of parametric amplification of a small signal pulse by an intense pump wave does not depend on the shape of the pump. The output is determined solely by the intensity of any TWI-solitons contained in the pump.

INTRODUCING PROOF TECHNIQUES USING THE LOGICAL GAME MINE HUNTER

This paper introduces a parallel fast converging Jacobi-like singular value decomposition (SVD) algorithm applicable to real-time signal processing of massive sensor arrays. The proposed algorithm highly increases the SVD convergence rate for larger matrices when compared with traditional Jacobi-based methods. A highly modular system design is proposed, which retains the parallel nature of the Jacobi methods key to real-time implementation intended for field programmable gated arrays (FPGAs). The proof of design was provided via an implementation on Virtex-6 FPGA, and the improvement in performance was verified via simulations. The proposed design was compared with the traditional design in terms of FPGA resource consumption, maximum achievable frequency, and latency throughput tradeoff.

Radioactive Decay: Audio Data Collection.

ABSTRACT The advantages of using the logical game Mine Hunter [1] to motivate and introduce proof techniques are discussed.