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Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Donald Umstadter Publications
A century ago, J. J. Thomson showed that the scattering of low-intensity light by electrons was a linear process (i.e., the scattered light frequency was identical to that of the incident light) and that light’s magnetic field played no role. To- day, with the recent invention of ultra-high-peak- power lasers it is now possible to create a sufficient photon density to study Thomson scattering in the relativistic regime. With increasing light intensity, electrons quiver during the scattering process with increasing velocity, approaching the speed of light when the laser intensity approaches 1018 W/cm2. In this limit, the …
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Donald Umstadter Publications
A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I=1.3×1018 W cm-2, λ =1.05 μm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8–100 nm when the pump laser power is increased from 0.45–2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump …
Exact Analytical Solution For The Vector Electromagnetic Field Of Gaussian, Flattened Gaussian, And Annular Gaussian Laser Modes, Scott M. Sepke, Donald Umstadter
Exact Analytical Solution For The Vector Electromagnetic Field Of Gaussian, Flattened Gaussian, And Annular Gaussian Laser Modes, Scott M. Sepke, Donald Umstadter
Donald Umstadter Publications
The exact vector integral solution for all the electromagnetic field components of a general flattened Gaussian laser mode is derived by using the angular spectrum method. This solution includes the pure and annular Gaussian modes as special cases. The integrals are of the form of Gegenbauer’s finite integral and are computed analytically for each case, yielding fields satisfying the Maxwell equations exactly in the form of quickly converging Fourier–Gegenbauer series.
Analytical Solutions For The Electromagnetic Fields Of Tightly Focused Laser Beams Of Arbitrary Pulse Length, Scott M. Sepke, Donald Umstadter
Analytical Solutions For The Electromagnetic Fields Of Tightly Focused Laser Beams Of Arbitrary Pulse Length, Scott M. Sepke, Donald Umstadter
Donald Umstadter Publications
The analytical solution for a monochromatic focused laser beam was recently published [Opt. Lett. 31, 1447 (2006)]. The effect of introducing bandwidth by including a finite-length temporal pulse envelope is included exactly. This is done formally first in the frequency domain for an arbitrary pulse shape, and the specific case of a cosine-squared envelope is then solved analytically for all pulse lengths, thereby decreasing the computation time by 2 orders of magnitude. The inclusion of longer wavelengths reduces the fraction of laser energy in the focus from 86.5% to 83.5% for a 5 fs Ti:sapphire laser and 72.7% in a …