Computational simulations for ensembles of luminescent silicon nanocrystals: Implications for optical gain and stimulated emission

2009 ◽  
Vol 41 (6) ◽  
pp. 955-958 ◽  
Author(s):  
A. Meldrum ◽  
R. Lockwood ◽  
V.A. Belyakov ◽  
V.A. Burdov
Keyword(s):  
Silicon Nanocrystals ◽  
Optical Gain ◽  
Stimulated Emission ◽  
Computational Simulations

Grains of Porous Silicon Embedded in SiO2:Studies of Optical Gain and Electroluminescence

2004 ◽  
Vol 99-100 ◽  
pp. 31-36 ◽  
Author(s):  
K. Dohnalová ◽  
K. Luterová ◽  
J. Valenta ◽  
Jiří Buršík ◽  
M. Procházka ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Silicon Nanocrystals ◽  
Visible Region ◽  
Optical Gain ◽  
Intrinsic Property ◽  
Stimulated Emission ◽  
Silicon Nanostructures ◽  
Porous Si ◽  
Si Nanocrystals ◽  
Excitation Spot

Recent reports on experimental observation of optical gain in silicon nanostructures in the visible region, performed at several laboratories all over the world, have triggered an extraordinary surge of interest in silicon lasing. However, attempts aimed at reproducing the red stimulated emission from „standard“silicon nanocrystals (sized 3-5 nm) at some other laboratories either failed, or. did not come to definite conclusions. Therefore, more detailed measurements of optical gain in a wider variety of samples containing Si nanocrystals are required in order to unravel whether or not the observation of optical gain is an intrinsic property of Si nanocrystals. We have performed a detailed study of optical gain in layers of densely packed Si nanocrystals in SiO2, prepared on the basis of porous Si, using the variable-stripe-length (VSL) method in combination with the shifted-excitation-spot (SES) method. In selected samples we have observed a distinct difference in behaviour between VSL and SES curves, indicating the occurrence of positive optical gain of ~ 24 cm-1. Preliminary reports on transport and electroluminescence measurements in thin films of SiO2 doped with porous silicon grains, prepared by spin-coating technique, are also discussed.

scholarly journals Silicon Nanocrystals: Fundamental Theory and Implications for Stimulated Emission

2008 ◽  
Vol 2008 ◽  
pp. 1-32 ◽  
Author(s):  
V. A. Belyakov ◽  
V. A. Burdov ◽  
R. Lockwood ◽  
A. Meldrum
Keyword(s):  
Energy Transfer ◽  
Silicon Nanocrystals ◽  
Light Emission ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Optical Gain ◽  
Stimulated Emission ◽  
Recombination Rates ◽  
Physical Mechanisms ◽  
Gain Profile

Silicon nanocrystals (NCs) represent one of the most promising material systems for light emission applications in microphotonics. In recent years, several groups have reported on the observation of optical gain or stimulated emission in silicon NCs or in porous silicon (PSi). These results suggest that silicon-NC-based waveguide amplifiers or silicon lasers are achievable. However, in order to obtain clear and reproducible evidence of stimulated emission, it is necessary to understand the physical mechanisms at work in the light emission process. In this paper, we report on the detailed theoretical aspects of the energy levels and recombination rates in doped and undoped Si NCs, and we discuss the effects of energy transfer mechanisms. The theoretical calculations are extended toward computational simulations of ensembles of interacting nanocrystals. We will show that inhomogeneous broadening and energy transfer remain significant problems that must be overcome in order to improve the gain profile and to minimize nonradiative effects. Finally, we suggest means by which these objectives may be achieved.

Optical gain and stimulated emission in silicon nanocrystals

2002 ◽  
Vol 738 ◽  
Author(s):  
L. Dal Negro ◽  
M. Cazzanelli ◽  
Z. Gaburro ◽  
P. Bettotti ◽  
L. Pavesi ◽  
...  
Keyword(s):  
Silicon Nanocrystals ◽  
Chemical Vapour ◽  
Optical Gain ◽  
Pump Intensity ◽  
Stimulated Emission ◽  
Thin Layers ◽  
Threshold Behaviour ◽  
Time Resolved ◽  
Emission Signal ◽  
Length Measurements

ABSTRACTTime-resolved luminescence measurements on silicon nanocrystal waveguides have revealed a fast recombination dynamics, related to population inversion which leads to net optical gain. The waveguide samples were obtained by thermal annealing of plasma enhanced chemical vapour deposited thin layers of silicon rich oxide Variable stripe length measurements performed on the fast emission signal have shown an exponential growth of the amplified spontaneous emission, with net gain values of about 10 cm-1. Both the fast component intensity and its temporal width revealed threshold behaviour as a function of the incident pump intensity. A modelling of the decay dynamics is suggested within an effective four level rate equation treatment including the delicate interplay among stimulated emission and Auger recombinations.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Signature of Generalized Gibbs Ensemble Deviation from Equilibrium: Negative Absorption Induced by a Local Quench

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 220
Author(s):  
Lorenzo Rossi ◽  
Fabrizio Dolcini ◽  
Fabio Cavaliere ◽  
Niccolò Traverso Ziani ◽  
Maura Sassetti ◽  
...  
Keyword(s):  
Optical Gain ◽  
Electron System ◽  
Bound State ◽  
Stimulated Emission ◽  
Optical Measurements ◽  
Gibbs Ensemble ◽  
Attractive Potential ◽  
Dimensional Electron System ◽  
Constants Of Motion ◽  
Generalized Gibbs Ensemble

When a parameter quench is performed in an isolated quantum system with a complete set of constants of motion, its out of equilibrium dynamics is considered to be well captured by the Generalized Gibbs Ensemble (GGE), characterized by a set {λα} of coefficients related to the constants of motion. We determine the most elementary GGE deviation from the equilibrium distribution that leads to detectable effects. By quenching a suitable local attractive potential in a one-dimensional electron system, the resulting GGE differs from equilibrium by only one single λα, corresponding to the emergence of an only partially occupied bound state lying below a fully occupied continuum of states. The effect is shown to induce optical gain, i.e., a negative peak in the absorption spectrum, indicating the stimulated emission of radiation, enabling one to identify GGE signatures in fermionic systems through optical measurements. We discuss the implementation in realistic setups.

Optical gain in silicon nanocrystals

2001 ◽  
Vol 17 (1-2) ◽  
pp. 41-44 ◽  
Author(s):  
L. Dal Negro ◽  
L. Pavesi ◽  
G. Pucker ◽  
G. Franzò ◽  
F. Priolo
Keyword(s):  
Silicon Nanocrystals ◽  
Optical Gain

scholarly journals Amplified Spontaneous Emission and Optical Gain in Organic Single Crystal Quinquethiophene

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 609 ◽  
Author(s):  
Muhammad Zeb ◽  
Muhammad Tahir ◽  
Fida Muhammad ◽  
Suhana Mohd Said ◽  
Mohd Faizul Mohd Sabri ◽  
...  
Keyword(s):  
Single Crystal ◽  
Spontaneous Emission ◽  
Threshold Energy ◽  
Pump Energy ◽  
Optical Gain ◽  
Amplified Spontaneous Emission ◽  
Stimulated Emission ◽  
Excitation Wavelength ◽  
Optical Amplification ◽  
Organic Single Crystal

In this paper, we report optical characteristics of an organic single crystal oligomer 5,5⁗-diphenyl-2,2′:5′,2″:5″,2‴:5‴,2⁗-quinquethiophene (P5T). P5T crystal is a thiophene/phenylene co-oligomer that possesses better charge mobility as well as photoluminescence quantum efficiency (PLQE) as compared to other organic materials. Stimulated emission in P5T is investigated via amplified spontaneous emission (ASE) measurements within broad pump energies ranging from 35.26 to 163.34 µJ/cm2. An Nd-YAG femtosecond-tunable pulsed laser is used as a pump energy source for the ASE measurements of P5T crystals at an excitation wavelength of 445 nm. The ASE spectra exhibit optical amplification in P5T crystals at a 625 nm peak wavelength with a lower threshold energy density (Eth) ≈ 52.64 μJ/cm2. P5T also demonstrates higher optical gain with a value of 72 cm−1, that is calculated by using the variable stripe-length method. The value of PLQE is measured to be 68.24% for P5T. This study proposes potential applications of P5T single crystals in organic solid state lasers, photodetectors, and optical amplifiers.

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