Quantum control and characterization of ultrafast ionization with orthogonal two-color laser pulses

Abstract Lasers, photovoltaics, and thermoelectrically-pumped light emitting diodes are thermodynamic machines which use excitons (electron-hole pairs) as the working medium. The heat transfers in such devices are highly irreversible, leading to low efficiencies. Here we predict that reversible heat transfers between a quantum-dot exciton and its phonon environment can be induced by laser pulses. We calculate the heat transfer when a quantum-dot exciton is driven by a chirped laser pulse. The reversibility of this heat transfer is quantified by the efficiency of a heat engine in which it forms the hot stroke, which we predict to reach 95% of the Carnot limit. This performance is achieved by using the time-dependent laser-dressing of the exciton to control the heat current and exciton temperature. We conclude that reversible heat transfers can be achieved in excitonic thermal machines, allowing substantial improvements in their efficiency.

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Temporal characterization of femtosecond laser pulses induced plasma for spectrochemical analysis of aluminum alloys

Spectrochimica Acta Part B Atomic Spectroscopy ◽

10.1016/s0584-8547(01)00187-2 ◽

2001 ◽

Vol 56 (6) ◽

pp. 987-1002 ◽

Cited By ~ 178

Author(s):

B. Le Drogoff ◽

J. Margot ◽

M. Chaker ◽

M. Sabsabi ◽

O. Barthélemy ◽

...

Keyword(s):

Aluminum Alloys ◽

Femtosecond Laser ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Spectrochemical Analysis

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Characterization of columns grown during KrF laser micromachining of Al2O3–TiC ceramics

Journal of Materials Research ◽

10.1557/jmr.2003.0154 ◽

2003 ◽

Vol 18 (5) ◽

pp. 1123-1130 ◽

Cited By ~ 6

Author(s):

V. Oliveira ◽

R. Vilar

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Laser Pulses ◽

Formation Mechanisms ◽

X Ray ◽

Reducing Conditions ◽

Transmission Electron ◽

Column Formation ◽

Krf Laser

This paper aims to contribute to the understanding of column formation mechanisms in Al2O3–TiC ceramics micromachined using excimer lasers. Chemical and structural characterization of columns grown in Al2O3–TiC composite processed with 200 KrF laser pulses at 10 J/cm2 was carried out by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction analysis. Fully developed columns consist of a core of unprocessed material surrounded by an outer layer of Al2TiO5, formed in oxidizing conditions, and an inner layer, formed in reducing conditions, composed of TiC and Al3Ti or an AlTi solid solution. Possible mechanisms of column formation are discussed.

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Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.16.15 ◽

2012 ◽

Vol 16 ◽

pp. 15-20 ◽

Cited By ~ 4

Author(s):

Omid Tayefeh Ghalehbeygi ◽

Vural Kara ◽

Levent Trabzon ◽

Selcuk Akturk ◽

Huseyin Kizil

Keyword(s):

Laser Ablation ◽

Femtosecond Laser ◽

Laser Beam ◽

Chemical Etching ◽

Silicon Surface ◽

Laser Pulses ◽

Laser Beam Profile ◽

Fs Laser ◽

Fabrication And Characterization

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

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