144 research outputs found
Strong-field Phenomena in Periodic Systems
The advent of visible-infrared laser pulses carrying a substantial fraction
of their energy in a single field oscillation cycle has opened a new era in the
experimental investigation of ultrafast processes in semiconductors and
dielectrics (bulk as well as nanostructured), motivated by the quest for the
ultimate frontiers of electron-based signal metrology and processing. Exploring
ways to approach those frontiers requires insight into the physics underlying
the interaction of strong high-frequency (optical) fields with electrons moving
in periodic potentials. This Colloquium aims at providing this insight.
Introduction to the foundations of strong-field phenomena defines and compares
regimes of field--matter interaction in periodic systems, including (perfect)
crystals as well as optical and semiconductor superlattices, followed by a
review of recent experimental advances in the study of strong-field dynamics in
crystals and nanostructures. Avenues toward measuring and controlling
electronic processes up to petahertz frequencies are discussed
Attosecond streaking enables the measurement of quantum phase
Attosecond streaking, as a measurement technique, was originally conceived as
a means to characterize attosecond light pulses, which is a good approximation
if the relevant transition matrix elements are approximately constant within
the bandwidth of the light pulse. Our analysis of attosecond streaking
measurements on systems with complex response to the photoionizing pulse
establishes a relation between the momentum-space wave function of the outgoing
electron and the result of conventional retrieval algorithms. This finding
enables the measurement of the quantum phase associated with bound-continuum
transition matrix elements.Comment: similar to the version accepted for publication in PR
Directly diode-pumped, Kerr-lens mode-locked, few-cycle Cr:ZnSe oscillator
Lasers based on Cr-doped II-VI material, often known as the
Ti:Sapphire of the mid-infrared, can directly provide few-cycle pulses with
super-octave-spanning spectra, and serve as efficient drivers for generating
broadband mid-infrared radiation. It is expected that the wider adoption of
this technology benefits from more compact and cost-effective embodiments.
Here, we report the first directly diode-pumped, Kerr-lens mode-locked
Cr-doped II-VI oscillator pumped by a single InP diode, providing
average powers of over 500 mW and pulse durations of 45 fs - shorter than six
optical cycles at 2.4 m. These correspond to a sixty-fold increase in peak
power compared to the previous diode-pumped record, and are at similar levels
with respect to more mature fiber-pumped oscillators. The diode-pumped
femtosecond oscillator presented here constitutes a key step towards a more
accessible alternative to synchrotron-like infrared radiation, and is expected
to accelerate research in laser spectroscopy and ultrafast infrared optics.Comment: 8 pages, 5 figure
Magyar TanĂtĂłkĂ©pzĹ‘ 17 (1902) 01
Magyar TanĂtĂłkĂ©pzĹ‘
A TanĂtĂłkĂ©pzĹ‘-intĂ©zeti Tanárok Országos EgyesĂĽletĂ©nek közlönye
17. Ă©vfolyam, 01. fĂĽzet
Budapest, 1902. január h
Multi-octave, CEP-stable source for high-energy field synthesis
The development of high-energy, high-power, multi-octave light transients is currently the subject of intense research driven by emerging applications in attosecond spectroscopy and coherent control. We report on a phase-stable, multi-octave source based on a Yb:YAG amplifier for light transient generation. We demonstrate the amplification of a two-octave spectrum to 25 mu J of energy in two broadband amplification channels and their temporal compression to 6 and 18 fs at 1 and 2 mu m, respectively. In this scheme, due to the intrinsic temporal synchronization between the pump and seed pulses, the temporal jitter is restricted to long-term drift. We show that the intrinsic stability of the synthesizer allows subcycle detection of an electric field at 0.15 PHz. The complex electric field of the 0.15-PHz pulses and their free induction decay after interaction with water molecules are resolved by electro-optic sampling over 2 ps. The scheme is scalable in peak and average power
Using the third state of matter: high harmonic generation from liquid targets
High harmonic generation on solid and gaseous targets has been proven to be a powerful platform for the generation of attosecond pulses. Here we demonstrate a novel technique for the XUV generation on a smooth liquid surface target in vacuum, which circumvents the problem of low repetition rate and limited shot numbers associated with solid targets, while it maintains some of its merits. We employed atomically smooth, continuous liquid jets of water, aqueous salt solutions and ethanol that allow uninterrupted high harmonic generation due to the coherent wake emission mechanism for over 8 h. It has been found that the mechanism of plasma generation is very similar to that for smooth solid target surfaces. The vapor pressure around the liquid target in our setup has been found to be very low such that the presence of the gas phase around the liquid jet could be neglected
Magyar TanĂtĂłkĂ©pzĹ‘ 18 (1903) 10
Magyar TanĂtĂłkĂ©pzĹ‘
A TanĂtĂłkĂ©pzĹ‘-intĂ©zeti Tanárok Országos EgyesĂĽletĂ©nek közlönye
18. Ă©vfolyam, 10. fĂĽzet
Budapest, 1903. december h
A concept for multiterawatt fibre lasers based on coherent pulse stacking in passive cavities
Since the advent of femtosecond lasers, performance improvements have constantly impacted on existing applications and enabled novel applications. However, one performance feature bearing the potential of a quantum leap for high-field applications is still not available: the simultaneous emission of extremely high peak and average powers. Emerging applications such as laser particle acceleration require exactly this performance regime and, therefore, challenge laser technology at large. On the one hand, canonical bulk systems can provide pulse peak powers in the multi-terawatt to petawatt range, while on the other hand, advanced solid-state-laser concepts such as the thin disk, slab or fibre are well known for their high efficiency and their ability to emit high average powers in the kilowatt range with excellent beam quality. In this contribution, a compact laser system capable of simultaneously providing high peak and average powers with high wall-plug efficiency is proposed and analysed. The concept is based on the temporal coherent combination (pulse stacking) of a pulse train emitted from a high-repetition-rate femtosecond laser system in a passive enhancement cavity. Thus, the pulse energy is increased at the cost of the repetition rate while almost preserving the average power. The concept relies on a fast switching element for dumping the enhanced pulse out of the cavity. The switch constitutes the key challenge of our proposal. Addressing this challenge could, for the first time, allow the highly efficient dumping of joule-class pulses at megawatt average power levels and lead to unprecedented laser parameters
- …