Femtosecond Laser Irradiation followed by Chemical Etching is exploited to create microfluidic devices for High-order Harmonic Generation (HHG) in noble gases. A finetuning of the channels’ diameter and length permits the production of high-order harmonics in completely different regimes, going from the hollow waveguiding regime to the sub-mm interaction regime. We envisage that the high adaptability of our microfluidic approach will allow us to integrate more functionalities in the same integrated device thus paving the way to palm-top HHG solutions.
By combining optical and x-ray transient data, we access the excited electron system and lattice of gold nanoparticle. The particle expansion starts already with the optical excitation pulse and thus occurs in the kinetic limit of the electron gas excitation. We present a new microscopic, parameter-free model that reproduces the experimental observations and leads to insight into ultrafast phenomena, which are addressed by the sampling of transient optical fields.
The possibility to obtain micrometric focal spot in the extreme-ultraviolet (XUV) region opens the way to XUV-XUV
experiments in high-order harmonics beamlines. A beamline designed for this purpose is here presented. The peculiarity
of the optical design relies on the use of only toroidal mirrors in place of the more expensive Cartesian optics. The coma
aberration, usually dominating the quality of the focal spot when toroidal mirrors are used with high levels of demagnification,
is compensated using mirrors in a subtractive (Z-shape) configuration. In addition, the compensating
output mirror decouples the length of the exit arm from the de-magnification factor, in this way the length of the exit arm
can be increased to install even a large experimental chamber. Three mirrors with optical power are required, in order to
assure an optimal focalization. In order to guarantee a day-to-day reproducible working condition, the mirrors are
mounted on remotely adjustable optical stages, that are controlled via a genetic algorithm with the feedback on the
quality of the focal spot. This solution helps the users to reach the best focalization conditions in a reliable way. The
results obtained during the beamline commissioning phase are presented. Emphasis is placed in the characterization of
the spot size and in the performances of the genetic algorithm.
The design of optical systems for micro-focusing of extreme-ultraviolet (XUV) and soft X-ray pulses through grazingincidence toroidal mirrors is presented. Aim of the configuration here presented is to provide a micro-focused image through a high demagnification of the source with almost negligible aberrations and a long exit arm to accommodate at the output a large experimental chamber. We present the analytical and numerical study of two configurations to fulfill these requirements with two toroidal mirrors. The first mirror provides a demagnified image of the source in the intermediate plane that is free from defocusing but has a large coma aberration, the second mirror is mounted in Z-shaped geometry with respect to the previous one, in order to give a stigmatic image with a coma that is opposite to that provided by the first one. Some examples are provided to demonstrate the capability to achieve spot sizes in the 5-15 μm range both applied to high-order laser harmonics and free-electron-laser radiation.
We review recent advances in the generation of isolated attosecond pulses, produced by using the process of
high-order harmonic generation in gases. In particular we report on a novel technique, based on the production
of a temporal gate obtained exploiting sub-cycle ionization dynamics of the neutral atom population. Isolated
attosecond pulses with time duration of 155 as and an energy on target of 2.1 nJ were generated and fully
characterized. Such isolated pulses can be used in attosecond pump-probe experiments to study ultra-fast
electronic dynamics in atoms and molecules with attosecond temporal resolution.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.