Experimental observation of polarization-resolved nonlinear Thomson scattering of elliptically polarized light

We report experimental results from a study of nonlinear Thomson scattering of elliptically polarized light. Polarization-resolved radiation patterns of the scattered light are measured as a function of the elliptical polarization state of the incident laser light. The relativistic electron trajectory in intense elliptically polarized fields leads to the formation of unique radiated polarization states, which are observed by our measurements and predicted by a theoretical model. The polarization of Thomson scattered light depends strongly on the intensity of the incident light due to nonlinearity. The results are relevant to high-field electrodynamics and to research and development of light sources with novel capabilities

Generation of ultrafast electron bunch trains via trapping into multiple periods of plasma wakefields

We demonstrate a novel approach to the generation of femtosecond electron bunch trains via laser-driven wakefield acceleration. We use two independent high-intensity laser pulses, a drive, and injector, each creating their own plasma wakes. The interaction of the laser pulses and their wakes results in a periodic injection of free electrons in the drive plasma wake via several mechanisms, including ponderomotive drift, wake-wake interference, and pre-acceleration of electrons directly by strong laser fields. Electron trains were generated with up to 4 quasi-monoenergetic bunches, each separated in time by a plasma period. The time profile of the generated trains is deduced from an analysis of beam loading and confirmed using 2D Particle-in-Cell simulations.Comment: 11 pages, 5 figures, accepted by Physics of Plasma

Wide-range Angle-sensitive Plasmonic Color Printing on Lossy-Resonator Substrates

We demonstrate a sustainable, lithography-free process for generating non fading plasmonic colors with a prototype device that produces a wide range of vivid colors in red, green, and blue (RGB) ([0-1], [0-1], [0-1]) color space from violet (0.7, 0.72, 1) to blue (0.31, 0.80, 1) and from green (0.84, 1, 0.58) to orange (1, 0.58, 0.46). The proposed color-printing device architecture integrates a semi-transparent random metal film (RMF) with a metal back mirror to create a lossy asymmetric Fabry-P\'erot resonator. This device geometry allows for advanced control of the observed color through the five-degree multiplexing (RGB color space, angle, and polarization sensitivity). An extended color palette is then obtained through photomodification process and localized heating of the RMF layer under various femtosecond laser illumination conditions at the wavelengths of 400 nm and 800 nm. Colorful design samples with total areas up to 10 mm2 and 100 {\mu}m resolution are printed on 300-nm-thick films to demonstrate macroscopic high-resolution color generation. The proposed printing approach can be extended to other applications including laser marking, anti-counterfeiting and chromo-encryption

Transverse oscillating bubble enhanced laser‑driven betatron X‑ray radiation generation

Ultrafast high-brightness X-ray pulses have proven invaluable for a broad range of research. Such pulses are typically generated via synchrotron emission from relativistic electron bunches using large-scale facilities. Recently, significantly more compact X-ray sources based on laser-wakefield accelerated (LWFA) electron beams have been demonstrated. In particular, laser-driven sources, where the radiation is generated by transverse oscillations of electrons within the plasma accelerator structure (so-called betatron oscillations) can generate highly-brilliant ultrashort X-ray pulses using a comparably simple setup. Here, we experimentally demonstrate a method to markedly enhance the parameters of LWFA-driven betatron X-ray emission in a proof-of-principle experiment. We show a significant increase in the number of generated photons by specifically manipulating the amplitude of the betatron oscillations by using our novel Transverse Oscillating Bubble Enhanced Betatron Radiation scheme. We realize this through an orchestrated evolution of the temporal laser pulse shape and the accelerating plasma structure. This leads to controlled off-axis injection of electrons that perform large-amplitude collective transverse betatron oscillations, resulting in increased radiation emission. Our concept holds the promise for a method to optimize the X-ray parameters for specific applications, such as time-resolved investigations with spatial and temporal atomic resolution or advanced high-resolution imaging modalities, and the generation of X-ray beams with even higher peak and average brightness

Fundamental Studies on Nonlinear Thomson Scattering

Thomson scattering is the name given to the scattering of light by electrons. This interaction is ubiquitous in daily life and responsible for a wealth interesting phenomenon. Additionally, the interaction can become nonlinear via relativistic effects further expanding its phenomenological reach. This work is dedicated to the study of these fundamental nonlinear interactions. The first chapter reviews theory for the relativistic nonlinearity induced by high intensity light fields interacting with electrons. A comprehensive theory is described with key insights into the origin of harmonics and understanding of nonlinearities. Then we experimentally demonstrate previously untested aspects of nonlinear Thomson scattering (NTS). First, we the study NTS in the mildly nonlinear regime with an elliptically driven laser pulse. This research bridges the experimental gap between NTS driven with linearly polarized laser fields and NTS driven with circularly polarized laser fields. It also reveals the complex polarization states of emitted radiation with applications in x-ray sources and cosmology. Next, we experimentally study the extremely nonlinear regime where the electron motion produces such high number of harmonics that they merge to a continuous broadband synchrotron spectrum. In this work, we study the spatial and spectral repercussions from the nonlinear motion of the electron. Thus, experimentally verifying untested theoretical work proposed over a century ago. Finally, we look toward future applications of highly NTS and propose a method to measure attosecond and sub-attosecond electron pulses. Such electron pulses have been proposed to study ultrafast atomic phenomenon, however, the ability to characterize the pulses is crucial. Our method is particularly valuable because it does not rely on a separate attosecond system as a clock for timing the electrons, of which there very few

Attosecond electron bunch measurement with coherent nonlinear Thomson scattering

We present a novel method for measurement of ultrashort electron-bunch duration, in principle, as short as zeptosecond (10−21 s). The method employs nonlinear Thomson scattering of relativistically intense laser light, and takes advantage of the nonlinear dependence and coherence of scattered light on electron bunch length. We validate the method and test its range of applicability via simulations by using realistic (nonideal) electron beams. Due to the wide flexibility in choice of interaction geometry and scattering laser pulse properties enabled by the method, it is shown to be applicable over a wide range of electron beam parameters, including energy, energy spread, and divergence angle

Attosecond electron bunch measurement with coherent nonlinear Thomson scattering

We present a novel method for measurement of ultrashort electron-bunch duration, in principle, as short as zeptosecond (10−21 s). The method employs nonlinear Thomson scattering of relativistically intense laser light, and takes advantage of the nonlinear dependence and coherence of scattered light on electron bunch length. We validate the method and test its range of applicability via simulations by using realistic (nonideal) electron beams. Due to the wide flexibility in choice of interaction geometry and scattering laser pulse properties enabled by the method, it is shown to be applicable over a wide range of electron beam parameters, including energy, energy spread, and divergence angle

Electron Trapping from Interactions between Laser-Driven Relativistic Plasma Waves

Interactions of large-amplitude relativistic plasma waves were investigated experimentally by propagating two synchronized ultraintense femtosecond laser pulses in plasma at oblique crossing angles to each other. The electrostatic and electromagnetic fields of the colliding waves acted to preaccelerate and trap electrons via previously predicted, but untested injection mechanisms of ponderomotive drift and wakewake interference. High-quality energetic electron beams were produced, also revealing valuable new information about plasma-wave dynamics