10 research outputs found
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
All-optical modulation with single-photons using electron avalanche
The distinctive characteristics of light such as high-speed propagation,
low-loss, low cross-talk and power consumption as well as quantum properties,
make it uniquely suitable for various critical applications in communication,
high-resolution imaging, optical computing, and emerging quantum information
technologies. One limiting factor though is the weak optical nonlinearity of
conventional media that poses challenges for the control and manipulation of
light, especially with ultra-low, few-photon-level intensities. Notably,
creating a photonic transistor working at single-photon intensities remains an
outstanding challenge. In this work, we demonstrate all-optical modulation
using a beam with single-photon intensity. Such low-energy control is enabled
by the electron avalanche process in a semiconductor triggered by the impact
ionization of charge carriers. This corresponds to achieving a nonlinear
refractive index of n2~7*10^-3m^2/W, which is two orders of magnitude higher
than in the best nonlinear optical media (Table S1). Our approach opens up the
possibility of terahertz-speed optical switching at the single-photon level,
which could enable novel photonic devices and future quantum photonic
information processing and computing, fast logic gates, and beyond.
Importantly, this approach could lead to industry-ready CMOS-compatible and
chip-integrated optical modulation platforms operating with single photons
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