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The amplification of light by a single excited molecule in free space is demonstrated in this paper. The extinction effect is the result of a destructive interference between the incident laser beam and the coherently scattered light from the molecule in the ground state. Thus, inversion of the population should lead to a phase shift of the scattered light and amplification of the laser light.
We investigate the phenomenon of resonant-infrared laser ablation of polymers using polystyrene as a model material. Ablation is initiated by a picosecond free-electron laser tuned to various infrared wavelengths that are resonant with vibrational modes of a polystyrene target. Time-resolved plume imaging, coupled with etch-depth measurements and finite-element calculations of the temperature rise...
We demonstrate robustly single-mode power scaling in fiber laser systems built using 35-mum core Yb-doped double-clad chirally-coupled-core (CCC) fibers. Up to 250 W have been demonstrated up to date and further power scaling is in progress.
Coherent terahertz emission and hard x-ray emission from a laser-driven plasma in a solid target are measured simultaneously revealing a complementary picture of the ultrafast plasma.
By repeated optical breakdown with focused femtosecond pulses, we decrease the refractive index of fused silica by few percent. The subsequent micro-lens formation is associated with a reduction of multiphoton absorption in all dielectrics.
We present a theoretical assessment of two open-path quantum cascade laser (QCL) approaches (mono/bi-static and backscatter) to measure ambient ozone and ammonia concentrations to within 1-10% accuracy at distances up to 10 km.
Concentrations of intrinsic structural defects in synthetic silica glass, AQT, were measured by highly sensitive ESR and photoluminescence measurements. It was revealed that the defects, influential for 193 nm absorption, were less than 1013 pcs/cm3.
An improved implementation of optical space domain reflectometry is presented using an interferometric characterization method and deconvolution technique. Reconstruction of a strong Bragg grating written in erbium fiber, with a qL ~ 8.6 is demonstrated.
We present a novel ultrafast pump-probe system, allowing for a drastic reduction in acquisition time, typically a few tens of minutes for 20,000 frames. We present acoustic waves and heat transfer measurements in nanometric layers.
Recent progress in quantum communication highlights the need of advanced non-Gaussian states exhibiting high purity and spatio-spectral single-mode characteristics. We employ tailored waveguides and photon counting to implement efficient state preparation suitable for quantum networks.
Using wavelengths between 2.6 and 3.8 microns from a fiber-based supercontinuum laser, lipids and proteins can be identified and selectively ablated. Absorption spectroscopy and selective ablation are conducted on atherosclerotic plaque constituents and adipose/fat tissues.
Probing ultrafast dynamics with electron pulses reveals information not accessible by other methods. Here we present two experiments where we have used electron pulses to observe molecular dynamics and to measure localized electromagnetic fields.
We report on the formation of second-harmonic whispering-gallery modes (SH-WGMs) on the tapered ZnO nanotetrapod legs. The SH-WGMs have strong dependence on the polarization of the fundamental infrared excitation beam relative to the crystal axis.
We used pump-probe technique to investigate recombination dynamics of photogenerated carriers in photodiodes consisting of InAs/GaInSb W-structured superlattices. Recombination time constants of 1.6 ns and 10 ns were measured under high and low powers, respectively.
We realized a continuous-wave terahertz spectrometer based on optical heterodyning of two near-infrared distributed-feedback diode lasers. Using active frequency stabilization we achieve 1 MHz resolution and a signal-to-noise ratio up to 80 dB.
We report detailed spectral and spatial characterization of a 0.1-MeV-0.8 MeV tunable ultra-bright laser-based Compton scattering source. Nuclear Resonance Fluorescence experiments with the source are also presented.
Atomic xenon ionization in ultra-strong laser fields is measured to give mega-electron volt photoelectrons. The yields and angular distributions for electrons above the ponderomotive energy are shown to be consistent with a semi-classical model.
The distribution of an ultrafast optical pulse train over multiple fiber links with long-term stable timing precision within 2 femtoseconds rms is accomplished by integrating a polarization maintaining output with 300 meter long fiber links.
Phase Doppler interferometry applied to spray research has improved combustion efficiency with emissions reductions and led to insights in atmospheric and meteorological research. Laser-induced incandescence is demonstrated as a means for monitoring combustion particulate emissions.
Spatially resolved spectral interferometry is used to measure the mode content of a Yb-doped photonic crystal-fiber amplifier having a 2300-mum2 mode area. The impact of misalignment at signal injection on the relative mode powers is quantified.
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