Pulsed Laser Interactions With Condensed Matter

1985 ◽  
Vol 51 ◽  
Author(s):  
N. Bloembergen
Keyword(s):  
Time Scale ◽  
Second Harmonic ◽  
Laser Pulses ◽  
Index Of Refraction ◽  
Fast Time ◽  
Electron Hole ◽  
Time Resolved ◽  
Short Laser Pulses ◽  
Femtosecond Regime ◽  
Ion Emission

ABSTRACTThe primary interaction is the absorption of photons by electrons. In metals free-free transitions increase the energy of the electron gas. In semiconductors and insulators electron-hole pairs are created, if the photon energy exceeds the band gap. If it is less, only multiphoton processes can initiate energy transfer from the light beam. In nearly all solid materials Auger processes and electron-phonon interactions occur on a picosecond time scale for the high density and energy of the carrier gas created by intense short laser pulses. Thus melting and evaporation of the material can occur on this time scale. These processes may be considered as the initial phases in the creation of laser produced plasmas. They have been studied by time-resolved measurements of the complex index of refraction, by electron and ion emission, by second harmonic generation, by electrical conductivity and other techniques. Fast time resolution is essential. The dynamic behavior of atoms and phase transitions in the picosecond and femtosecond regime has been opened up for experimental investigation.

Near-Field Second Harmonic Microscopy of Thin Ferroelectric Films

1999 ◽  
Vol 596 ◽  
Author(s):  
I. I. Smolyaninov ◽  
H. Y. Liang ◽  
C. H. Lee ◽  
C. C. Davis ◽  
L. D. Rotter ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Near Field ◽  
Laser System ◽  
Optical Resolution ◽  
Optical Probe ◽  
Ferroelectric Materials ◽  
Scanning Probe ◽  
Fast Time ◽  
Regenerative Amplifier ◽  
Time Resolved

AbstractNear-field second harmonic microscopy is ideally suited for studies of local nonlinearity and poling of ferroelectric materials at the microscopic level. Its main advantages in comparison with other scanning probe techniques are the possibility of fast time-resolved measurements, and substantially smaller perturbation of the sample under investigation caused by the optical probe. We report second harmonic imaging of the surface of thin BaTiO3 films obtained in a near-field microscopy setup using a Ti:sapphire laser system consisting of an oscillator and a regenerative amplifier operating at 810 nm. Optical resolution on the order of 80 nm has been achieved.

scholarly journals Experimental and numerical study of ultra-short laser-produced collimated Cu Kα X-ray source

2017 ◽  
Vol 35 (3) ◽  
pp. 442-449 ◽  
Author(s):  
R. Rathore ◽  
V. Arora ◽  
H. Singhal ◽  
T. Mandal ◽  
J.A. Chakera ◽  
...  
Keyword(s):  
Laser Intensity ◽  
Numerical Study ◽  
Low Cost ◽  
Laser Pulses ◽  
Photon Flux ◽  
X Rays ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Short Laser Pulses

AbstractKα X-ray sources generated from the interaction of ultra-short laser pulses with solids are compact and low-cost source of ultra-short quasi-monochromatic X-rays compared with synchrotron radiation source. Development of collimated ultra-short Kα X-ray source by the interaction of 45 fs Ti:sapphire laser pulse with Cu wire target is presented in this paper. A study of the Kα source with laser parameters such as energy and pulse duration was carried out. The observed Kα X-ray photon flux was ~2.7 × 108 photons/shot at the laser intensity of ~2.8 × 1017 W cm−2. A model was developed to analyze the observed results. The Kα radiation was coupled to a polycapillary collimator to generate a collimated low divergence (0.8 mrad) X-ray beam. Such sources are useful for time-resolved X-ray diffraction and imaging studies.

Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction

2009 ◽  
Vol 1172 ◽  
Author(s):  
Anja Hanisch-Blicharski ◽  
Boris Krenzer ◽  
Simone Möllenbeck ◽  
Manuel Ligges ◽  
Ping Zhou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Temperature Rise ◽  
Laser Fluence ◽  
Initial Temperature ◽  
Laser Excitation ◽  
Laser Pulses ◽  
High Energy ◽  
Time Resolved ◽  
Thermal Boundary Conductance ◽  
Short Laser Pulses

AbstractWith time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm2K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model.

scholarly journals Time-Resolved Spectroscopy of Plasma Resonances In Highly Excited Silicon And Germanium

1985 ◽  
Vol 51 ◽  
Author(s):  
A. M. Malvezzi ◽  
C. Y. Huang ◽  
H. Kurz ◽  
N. Bloembergen
Keyword(s):  
Thermal Model ◽  
Near Infrared ◽  
Laser Pulses ◽  
Band Gaps ◽  
Strong Increase ◽  
Electron Hole ◽  
Time Resolved ◽  
Electron Hole Plasma ◽  
Silicon And Germanium ◽  
532 Nm

ABSTRACTThe dynamics of the electron-hole plasma in silicon and germanium samples irradiated by 20 ps, 532 nm laser pulses has been investigated in the near infrared by time-resolved picosecond optical spectroscopy. The experimental reflectivities and transmissions are compared with the redictions of the thermal model for degenerate carrier distributions through the Drue iformalism. Above a certain fluence, a significant deviation between measured and calculated values indicates a strong increase of the recombination rate as soon as the plasma resonances become comparable with the band gaps. These new plasmon-aided recombination channels are particularly pronounced in germanium.

Sign in / Sign up

Export Citation Format

Share Document