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We present the measurement of χ(3) nonlinearity of Green Fluorescent Protein. The nonlinear index is n2 = 10−19m2/W, opening the possibility of using genetically engineerable and naturally occuring proteins in cells as a source of four wave mixing experiments.
We investigate deformations of fluid interfaces caused by small (∼nN) optical force of a low power laser beam under total-internal-reflection. For air-water interface deformations are undetectable, unlike recently claimed in ref. [3]. Using a critical fluid-fluid interface having weak surface tension large fluid-lens effects in the form of a bump are seen. Our observations support standard optofluidic...
We measure the polarization evolution of ultrashort pulses (filaments) propagating in air for various pulse widths and energies. We observe the change of light ellipticity close to circular polarization.
We validate the use of a quadriwave lateral shearing Wave Front Sensor (WFS) to make an ISO compliant M2 measurement. We compare measurements made following the ISO standard method with those made with the WFS.
The unique combination of the LCLS x-ray laser with high-power nanosecond and femtosecond laser beams at the Matter of Extreme Conditions allows precision pump-probe studies of high energy density plasmas. For this purpose, we are building a new 200 TW laser system to measure and uncover the underlying physics mechanism that determine the interaction of ultra intense laser beams with matter. The repetition...
A fiber-coupled, 10-kHz, UV-PLIF and PIV combined detection system employing a common 6-m-long optical fiber is developed for simultaneous 2D fields of OH radical concentration and velocity measurements in practical combustion facilities.
A method for measuring optical thickness changes in a thin film using a single laser beam is proposed and demonstrated. Theory suggests that when a half plane phase shift is applied to a Gaussian laser beam, interference fringes appear in the far field which position varies with the amount of phase shift. By measuring fringe pattern displacements, we demonstrate detection of optical changes in microns-thick...
We achieve in situ, micron-scale tracking of laser machining through a galvo-telecentric beam delivery system using coherent imaging. We collect both high speed intrapulse and interpulse morphology changes as well as overall sweep-to-sweep depth penetration.
The mechanism of the nonlinear photo-carrier generation in low-temperature-grown GaAs by 1.5 μm pulses was investigated by a double pulse experiment. The effect of intermediate excitation on the photo response was distinctly observed. Moreover, the effect was found to be largely coherent, contrary to the proposed model.
The carrier envelope phase shift of a stacked picosecond pulse train for Compton scattering experiments have been measured to an accuracy of 80 mrad by spectrally resolved interference pattern of a stabilized multiple beam interferometer.
A fourth-harmonic (263-nm) probe beam has been commissioned on OMEGA EP. A novel diagnostic has been developed for it to diagnose plasma-density profiles using angular spectral filters to generate a contour map of refractive angles.
We present a new method to measure particle mass based on a shaped, divergent laser beam using the inertia-dependent particle movement inside an optical light scattering measurement chamber.
We report on the recent contrast enhancement of Astra-Gemini laser. It is shown that the stretcher gratings contribute significantly to the contrast pedestal. Implementing higher-quality gratings resulted in a significant contrast improvement. We have also investigated and quantified the contribution to the contrast pedestal from each individual grating in the stretcher.
Development of an ultra-sensitive, selective, and compact QEPAS-based CO sensor employing a high power CW DFB-QCL is reported. A minimum detectable concentration of 4ppbv was achieved for CO line (2169.2cm−1) using a 5sec data acquisition time.
We present experimental and numerical investigation of a new filamentation regime of mid-infrared femtosecond pulses in solids. Efficient emission of dispersive waves without fundamental spectrum broadening and continuum generation is observed in this regime.
We show that a localized and long-lived quasi-stationary gas density depression exists after filament-generated-plasma recombination. Its millisecond timescale dynamics is governed by thermal diffusion and has strong effects on high-repetition-rate filamentation and supercontinuum generation.
Super-luminescent jet light is produced via disrupted conical emission excited by focused millijoule 50 fs laser pulses in air. Phase-matching requirement of four-wave mixing at specific diffraction angles is responsible for the observed phenomenon.
We experimentally measure the profile of a THz beam generated by a two-color air plasma as it passes through a beam waist, and show that it can be approximated as a Bessel-Gauss beam.
We demonstrate a variable-focus technique for characterizing the beam quality of general astigmatic (twisted) laser beams. There are no moving parts, only a focus-tunable lens. Measurements with this method match those made by the standard technique.
We demonstrated a three-stage Cr:ZnSe power-amplifier pumped with a Tm:YAG laser. Maximum pulse energy of 52.2 mJ was obtained at 2.41 μm in the three-stage Cr:ZnSe power amplifier. Energy conversion efficiency of the Cr:ZnSe power amplifier reached more than 44%.
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