scholarly journals Coherent modulation of the electron temperature and electron–phonon couplings in a 2D material

2020 ◽  
Vol 117 (16) ◽  
pp. 8788-8793 ◽  
Author(s):  
Yingchao Zhang ◽  
Xun Shi ◽  
Wenjing You ◽  
Zhensheng Tao ◽  
Yigui Zhong ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Phonon Scattering ◽  
Density Wave ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Coupling Mechanism ◽  
Temperature Modulation ◽  
Light Pulses ◽  
Ultrashort Light Pulses ◽  
Multiple Materials

Ultrashort light pulses can selectively excite charges, spins, and phonons in materials, providing a powerful approach for manipulating their properties. Here we use femtosecond laser pulses to coherently manipulate the electron and phonon distributions, and their couplings, in the charge-density wave (CDW) material 1T-TaSe2. After exciting the material with a femtosecond pulse, fast spatial smearing of the laser-excited electrons launches a coherent lattice breathing mode, which in turn modulates the electron temperature. This finding is in contrast to all previous observations in multiple materials to date, where the electron temperature decreases monotonically via electron–phonon scattering. By tuning the laser fluence, the magnitude of the electron temperature modulation changes from ∼200 K in the case of weak excitation, to ∼1,000 K for strong laser excitation. We also observe a phase change of π in the electron temperature modulation at a critical fluence of 0.7 mJ/cm2, which suggests a switching of the dominant coupling mechanism between the coherent phonon and electrons. Our approach opens up routes for coherently manipulating the interactions and properties of two-dimensional and other quantum materials using light.

scholarly journals Ultrashort Light Pulses in Transparent Solids: Propagation Peculiarities and Practical Applications

2019 ◽  
Vol 64 (6) ◽  
pp. 457
Author(s):  
I. V. Blonskyi ◽  
V. M. Kadan ◽  
S. V. Pavlova ◽  
I. A. Pavlov ◽  
O. I. Shpotyuk ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Time Resolved ◽  
Transmission Microscopy ◽  
Practical Applications ◽  
Kerr Media ◽  
Light Pulses ◽  
Ultrashort Light Pulses ◽  
Femtosecond Filamentation ◽  
First Time

The peculiarities of the femtosecond filamentation in Kerr media has been studied using a set of time-resoling experimental techniques. These include the temporal self-compression of a laser pulse in the filamentation mode, repulsive and attractive interactions of filaments, and influence of the birefringence on the filamentation. The propagation of femtosecond laser pulses at the 1550-nm wavelength in c-Si is studied for the first time using methods of time-resolved transmission microscopy. The nonlinear widening of the pulse spectrum due to the Kerr- and plasma-caused self-phase modulation is recorded.

scholarly journals Coherent control in the extreme ultraviolet and attosecond regime by synchrotron radiation

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Y. Hikosaka ◽  
T. Kaneyasu ◽  
M. Fujimoto ◽  
H. Iwayama ◽  
M. Katoh
Keyword(s):  
Synchrotron Radiation ◽  
Coherent Control ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Light Sources ◽  
Light Pulses ◽  
Research Areas ◽  
Control Research

Abstract Quantum manipulation of populations and pathways in matter by light pulses, so-called coherent control, is currently one of the hottest research areas in optical physics and photochemistry. The forefront of coherent control research is moving rapidly into the regime of extreme ultraviolet wavelength and attosecond temporal resolution. This advance has been enabled by the development of high harmonic generation light sources driven by intense femtosecond laser pulses and by the advent of seeded free electron laser sources. Synchrotron radiation, which is usually illustrated as being of poor temporal coherence, hitherto has not been considered as a tool for coherent control. Here we show an approach based on synchrotron radiation to study coherent control in the extreme ultraviolet and attosecond regime. We demonstrate this capability by achieving wave-packet interferometry on Rydberg wave packets generated in helium atoms.

scholarly journals Ultrafast pulse shaping modulates perceived visual brightness in living animals

2021 ◽  
Vol 7 (18) ◽  
pp. eabe1911
Author(s):  
Geoffrey Gaulier ◽  
Quentin Dietschi ◽  
Swarnendu Bhattacharyya ◽  
Cédric Schmidt ◽  
Matteo Montagnese ◽  
...  
Keyword(s):  
Pulse Shaping ◽  
Single Pulse ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Light Pulses ◽  
Light Excitation ◽  
Interaction Regime ◽  
Dynamics Simulations ◽  
Electric Signals ◽  
Multiphoton Interaction

Vision is usually assumed to be sensitive to the light intensity and spectrum but not to its spectral phase. However, experiments performed on retinal proteins in solution showed that the first step of vision consists in an ultrafast photoisomerization that can be coherently controlled by shaping the phase of femtosecond laser pulses, especially in the multiphoton interaction regime. The link between these experiments in solution and the biological process allowing vision was not demonstrated. Here, we measure the electric signals fired from the retina of living mice upon femtosecond multipulse and single-pulse light stimulation. Our results show that the electrophysiological signaling is sensitive to the manipulation of the light excitation on a femtosecond time scale. The mechanism relies on multiple interactions with the light pulses close to the conical intersection, like pump-dump (photoisomerization interruption) and pump-repump (reverse isomerization) processes. This interpretation is supported both experimentally and by dynamics simulations.

X-Ray Production and Second Harmonic Generation by Superintense Femtosecond Laser Pulses in the Solids with Restricted Thermal Conduction

1997 ◽  
Vol 06 (04) ◽  
pp. 495-505 ◽  
Author(s):  
V. G. Babaev ◽  
M. S. Dzhidzhoev ◽  
V. M. Gordienko ◽  
M. A. Joukov ◽  
A. B. Savel'ev ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Thermal Conduction ◽  
Second Harmonic ◽  
Carbon Film ◽  
Laser Pulses ◽  
Carbon Films ◽  
Femtosecond Laser Pulses ◽  
X Ray ◽  
Observed Behaviour ◽  
Freely Suspended

Two new types of targets: ultrathin freely suspended carbon films and porous Si, both revealing thermoconductivity restriction leading to plasma overheating upto electron temperature above 1 keV under "moderate" intensities 1015 - 1016 W · cm-2 has been investigated experimentally. For the ultrathin carbon film of 20–30 nm X-ray yield threefold increase has been observed. Computer simulations decribe well the observed behaviour of the X-ray yield, and the electron temperature of 700 eV was deducted for the film of 10 nm in thickness. Por-Si produces greater X-ray flux under intensity of 1016 W · cm-2 as compared to the solid Si. If the intensity increased the total X-ray yield from por-Si undergoes "saturation", while the X-ray yield from solid Si fits as ≈ I2. Simple model to describe the "overheating" of Si plasma using a set of ultrathin films is developed. Some promising advantages of new targets are discussed.

Investigation of characteristic x-rays and hot-electron temperature in the interaction of normally incident femtosecond laser pulses with nanostructured foils

2014 ◽  
Vol 89 (7) ◽  
pp. 075605 ◽  
Author(s):  
O F Kostenko ◽  
A V Ovchinnokov ◽  
O V Chefonov ◽  
S A Romashevskiy ◽  
V P Petrovskiy ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Electron Temperature ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
X Rays ◽  
Hot Electron

scholarly journals Non-Fourier Estimate of Electron Temperature in Case of Femtosecond Laser Pulses Interaction with Metals

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 606 ◽  
Author(s):  
Anca M. Bucă ◽  
Mihai Oane ◽  
Muhammad Arif Mahmood ◽  
Ion N. Mihăilescu ◽  
Andrei C. Popescu ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Electron Temperature ◽  
Relaxation Times ◽  
Gold Surface ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
New Approach ◽  
Thermal Fields ◽  
Coupling Factors

This work is devoted to the electron temperature variation in metals through interaction with femtosecond laser pulses. Our study was inspired by the last mathematical breakthroughs regarding the exact analytical solutions of the heat equation in the case of flash laser-matter interaction. To this purpose, the classical Anisimov’s two temperature model was extended via the 3D telegraph Zhukovsky equation. Based upon this new approach, the computational plots of electron thermal fields during the first laser pulse interaction with a gold surface were inferred. It is shown that relaxation times and coupling factors over electron thermal conductivities (g/K) govern the interaction between the laser pulse and metal sample during the first picoseconds. The lower the factor g/K, the higher the electron temperature becomes. In contrast, the lower the relaxation time, the lower the electron temperature.

scholarly journals Femtosecond Laser Pulses: Generation, Measurement and Propagation

2021 ◽  
Author(s):  
Mounir Khelladi
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Ultrashort Laser Pulse ◽  
Short Pulse ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Light Pulses ◽  
Large Bandwidth ◽  
Temporal Shape ◽  
Ultrashort Laser

In this contribution some basic properties of femtosecond laser pulse are summarized. In sections 2.1–2.5 the generation of femtosecond laser pulses via mode locking is described in simple physical terms. In section 2.6 we deal with measurement of ultrashort laser pulses. The characterization of ultrashort pulses with respect to amplitude and phase is therefore based on optical correlation techniques that make of the short pulse itself. In section 3 we start with the linear properties of ultrashort light pulses. However, due to the large bandwidth, the linear dispersion is responsible for dramatic effects. To describe and manage such dispersion effects a mathematical description of an ultrashort laser pulse is given first before we continue with methods how to change the temporal shape via the frequency domain. The chapter ends with a paragraph of the wavelet representation of an ultrashort laser pulse.

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