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.

Time-Resolved Optical Studies of Picosecond Laser Interactions With Gaas Surfaces

1985 ◽  
Vol 51 ◽  
Author(s):  
J.M. Liu ◽  
A.M. Malvezzi ◽  
N. Bloembergen
Keyword(s):  
Picosecond Laser ◽  
Laser Pulses ◽  
Wavelength Dependence ◽  
Electron Hole ◽  
Molten Layer ◽  
Time Resolved ◽  
High Fluences ◽  
Electron Hole Plasma ◽  
Vapor Cloud ◽  
Melting Threshold

ABSTRACTThe interactions of picosecond laser pulses at 532 nm wavelength with GaAs surfaces have been studied with time-resolved reflectivity and transmission measurements at three probe wavelengths. At fluences below the melting threshold, the laser-generated electron-hole plasma is limited to a density below ≈1020cm−3. The high reflectivities of molten GaAs observed at fluences above the tlhreshold have a wavelength dependence inconsistent with a simple Drude model for a metallic GaAs molten layer. At high fluences, the evolution of a laser-induced vapor cloud is observed.

Robust single-mode lasers based on hexagonal CdS microflakes

2020 ◽  
Vol 8 (32) ◽  
pp. 11201-11208
Author(s):  
Yang Mi ◽  
Yaoyao Wu ◽  
Jinchun Shi ◽  
Sheng-Nian Luo
Keyword(s):  
Radiative Recombination ◽  
Single Mode ◽  
Whispering Gallery Mode ◽  
Radiative Recombination Rate ◽  
Electron Hole ◽  
High Quality ◽  
Time Resolved ◽  
Whispering Gallery ◽  
Electron Hole Plasma ◽  
Time Resolved Photoluminescence

We have achieved single-mode whispering-gallery-mode lasing in CdS microflakes with sharp linewidth (∼0.12 nm) and high quality factor (∼4200). Such lasers are superior to previous CdS lasers in these lasing parameters. Through time-resolved photoluminescence measurements, electron–hole plasma recombination is established to be the lasing mechanism. The radiative recombination rate of CdS microflakes is enhanced by a factor of ∼4.7 due to the Purcell effect.

Structural changes in GaAs induced by ultrafast (fs) laser pulses

1998 ◽  
Vol 13 (7) ◽  
pp. 1808-1811 ◽  
Author(s):  
L. Nánai ◽  
R. Vajtai ◽  
Cs. Beleznai ◽  
J. Remes ◽  
S. Leppävuori ◽  
...  
Keyword(s):  
Structural Changes ◽  
Microprobe Analysis ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Electron Hole ◽  
Zinc Blend ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Hole Plasma ◽  
Fs Laser

Ultrafast changes in the crystal structure of GaAs induced by intense femtosecond laser pulses are detected and investigated. Atomic force microscopy and Raman microprobe analysis of the laser-treated area show centrosymmetric (disordered) features which are different from the original zinc-blend structure of the GaAs lattice. The frozen-in structure shows evidence for a special heat transfer from the laser-induced crater to the boundary, namely the heat has been transferred ballistically by a high-density electron-hole plasma.

Recombination of an electron-hole plasma in silicon under the action of femtosecond laser pulses

JETP Letters ◽  
2004 ◽  
Vol 79 (11) ◽  
pp. 529-531 ◽  
Author(s):  
S. I. Ashitkov ◽  
A. V. Ovchinnikov ◽  
M. B. Agranat
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Electron Hole ◽  
Hole Plasma ◽  
Electron Hole Plasma

scholarly journals An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

2021 ◽  
Vol 75 (7) ◽  
Author(s):  
Lorenzo Stella ◽  
Jonathan Smyth ◽  
Brendan Dromey ◽  
Jorge Kohanoff
Keyword(s):  
Relaxation Time ◽  
Free Electron ◽  
Laser Pulses ◽  
Hole Pair ◽  
Electron Hole ◽  
Electron Hole Plasma ◽  
High Intensity Laser ◽  
Electron Hole Pair ◽  
Intensity Laser ◽  
Two Temperature

Abstract The relaxation of free electron–hole pairs generated after proton irradiation is modelled by means of a simplified set of hydrodynamic equations. The model describes the coupled evolution of the electron–hole pair and self-trapped exciton (STE) densities, along with the electronic and lattice temperatures. The equilibration of the electronic and lattice excitations is based on the two-temperature model, while two mechanisms for the relaxation of free electron–hole pairs are considered: STE formation and Auger recombination. Coulomb screening and band gap renormalisation are also taken into account. Our numerical results show an ultrafast ($${\ll }\,{\mathrm {1}}$$ ≪ 1 ps) free electron–hole pair relaxation time in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 for initial carrier densities either below or above the exciton Mott transition. Coulomb screening alone is not found to yield the long relaxation time ($${\mathrm {\gg }}{\mathrm {10}}$$ ≫ 10 ps) experimentally observed in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 and borosilicate crown glass BK7 irradiated with high-intensity laser pulses or BK7 irradiated by short proton pulses. Another mechanism, e.g. thermal detrapping of STEs, is required to correctly model the long free electron–hole pair relaxation time observed experimentally. Graphical Abstract

Laser Ablation-Induced Plasma Characteristics in Optical Near-Field

2007 ◽  
Author(s):  
David J. Hwang ◽  
Hojeong Jeon ◽  
Costas P. Grigoropoulos
Keyword(s):  
Near Infrared ◽  
Near Field ◽  
Laser Pulses ◽  
Thin Metal Film ◽  
Nanosecond Laser ◽  
Time Resolved ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Nanosecond Laser Pulses ◽  
Plasma Characteristics

In this study, detailed characteristics of the optical near-field based ablation-induced plasma are investigated. A Cr thin metal film samples are ablated using visible and near infrared nanosecond laser pulses coupled through an optical near-field fiber probe. The ablated plasma evolution is visualized through time-resolved emission imaging and further analyzed via spectral measurement. Unveiled qualitative differences in optical near-field ablation configuration are discussed in comparison with optical far-field ablation. The measured results support implementation of laser-induced breakdown spectroscopy based on optical near-field ablation.

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