scholarly journals Low- and High-Order Nonlinear Optical Characterization of Metal Sulfide Quantum Dots -=SUP=-*-=/SUP=-

2019 ◽  
Vol 127 (8) ◽  
pp. 291
Author(s):  
R.A. Ganeev
Keyword(s):  
Quantum Dots ◽  
Nonlinear Optical ◽  
Extreme Ultraviolet ◽  
Nonlinear Refraction ◽  
Metal Sulfide ◽  
Laser Pulses ◽  
High Order ◽  
Ultrashort Laser Pulses ◽  
Practical Applications ◽  
Ultraviolet Range

Any new synthesized semiconductor nanoparticles or quantum dots (QDs) require to be examined under different conditions using laser pulses of variable energies, wavelengths and durations to understand the nonlinear optical mechanisms and distinguish their attractive properties for practical applications. Among various QDs the metal sulfides took special attention due to their advanced nonlinear optical properties. Additionally, laser ablation can readily produce plasmas containing QDs that could be used for different applications. One of them is that they can be used as emitters for harmonic generation from ultrashort laser pulses. Here we review recent studies of different low- and high-order optical nonlinearities of metal sulfide QDs, such as optical limiting, two-photon, saturable and reverse saturable types of nonlinear absorption, nonlinear refraction, and generation of high-order harmonics in extreme ultraviolet range.

scholarly journals Application of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas

2019 ◽  
Vol 9 (8) ◽  
pp. 1701 ◽  
Author(s):  
R. A. Ganeev ◽  
S. Y. Stremoukhov ◽  
A. V. Andreev ◽  
A. S. Alnaser
Keyword(s):  
Extreme Ultraviolet ◽  
Laser Pulses ◽  
Plasma Jets ◽  
High Order ◽  
Ultrashort Laser Pulses ◽  
Phase Matching ◽  
Quasi Phase Matching ◽  
Fundamental Radiation ◽  
Formation Conditions ◽  
The One

Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single- and two-color femtosecond pulses through multi-jet plasmas, which allows the enhancement of groups of harmonics in different ranges of extreme ultraviolet. The role of the number of coherent zones; sizes of plasma jets and the distance between them; plasma formation conditions, and the characteristics of the fundamental radiation on the harmonic efficiency at quasi-phase matching (QPM) conditions are analyzed. We demonstrate the ~40× enhancement factor of the maximally-enhanced harmonic with respect to the one generated at ordinary conditions in the imperforated plasma.

scholarly journals Nonlinear Absorption and Refraction of Picosecond and Femtosecond Pulses in HgTe Quantum Dot Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3351
Author(s):  
Arturs Bundulis ◽  
Ivan A. Shuklov ◽  
Vyacheslav V. Kim ◽  
Alaa A. Mardini ◽  
Jurgis Grube ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Nonlinear Absorption ◽  
Nonlinear Refraction ◽  
Tunable Laser ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Saturable Absorption ◽  
Femtosecond Pulses ◽  
Laser Mode ◽  
Ultrashort Laser

We report measurements of the saturated intensities, saturable absorption, and nonlinear refraction in 70-nm thick films containing 4 nm HgTe quantum dots. We demonstrate strong nonlinear refraction and saturable absorption in the thin films using tunable picosecond and femtosecond pulses. Studies were carried out using tunable laser pulses in the range of 400–1100 nm. A significant variation of the nonlinear refraction along this spectral range was demonstrated. The maximal values of the nonlinear absorption coefficients and nonlinear refractive indices determined within the studied wavelength range were −2.4 × 10−5 cm2 W−1 (in the case of 28 ps, 700 nm probe pulses) and −3 × 10−9 cm2 W−1 (in the case of 28 ps, 400 nm probe pulses), respectively. Our studies show that HgTe quantum dots can be used in different fields e.g., as efficient emitters of high-order harmonics of ultrashort laser pulses or as laser mode-lockers.

scholarly journals Effects of Laser Plasma Formation on Quasi-Phase Matching of High-Order Harmonics from Nanoparticles and Atoms

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 572 ◽  
Author(s):  
Rashid Ganeev ◽  
Ganjaboy Boltaev ◽  
Vyacheslav Kim ◽  
Chunlei Guo
Keyword(s):  
Laser Ablation ◽  
Laser Plasma ◽  
Extreme Ultraviolet ◽  
Laser Pulses ◽  
Plasma Formation ◽  
High Order ◽  
Ultrashort Laser Pulses ◽  
Phase Matching ◽  
Laser Plasmas ◽  
Quasi Phase Matching

The application of nanoparticles (NPs) and quasi-phase matching (QPM) each play an important role in the enhancement of high-order harmonics (HHG) of ultrashort laser pulses. We analyze various regimes of nanoparticle plasma formation for the creation conditions for maximal QPM-induced enhancement of the groups of harmonics in the extreme ultraviolet (XUV). Laser plasmas were formed on the surfaces of NPs- and microparticle (MPs)-contained targets using ablation by nanosecond, picosecond, and femtosecond pulses. Different conditions of laser plasma formation (extended and perforated plasma) and variable concentrations of free electrons in these three cases of laser ablation led to modifications of QPM conditions. We demonstrate novel approaches in the optimization of QPM at the conditions of laser ablation of NPs and MPs by pulses of different durations. The formation of QPM conditions using femtosecond and picosecond heating pulses during HHG in such plasmas allowed the growth of conversion efficiency of the groups of harmonics, with the enhancement factors exceeding 25× in different ranges of XUV, contrary to less efficient QPM in the case of nanosecond pulse-induced ablation.

scholarly journals Нелинейно-оптические свойства квантовых точек CdS/ZnS в матрице из высокомолекулярного поливинилпирролидона

2018 ◽  
Vol 52 (8) ◽  
pp. 865
Author(s):  
А.С. Кулагина ◽  
С.К. Евстропьев ◽  
Н.Н. Розанов ◽  
В.В. Власов
Keyword(s):  
Quantum Dots ◽  
Nonlinear Optical ◽  
Quantum Confinement Effect ◽  
Nonlinear Refraction ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Nonlinear Properties ◽  
Two Photon ◽  
Optical Limitation

AbstractSols containing core/shell CdS/ZnS semiconductor quantum dots are synthesized and their nonlinear properties, which are interesting for a large variety of applications in nanophotonics, are studied. The quantum dots produced are smaller in dimensions than the exciton Bohr radius and, therefore, exhibit a well-pronounced quantum-confinement effect. The nonlinear optical properties of low-concentration sols are studied upon exposure to laser pulses with an emission wavelength of 532 nm and a duration of 5 ns by the z-scan technique. The dependences of nonlinear optical coefficients on the concentration of CdS/ZnS quantum dots are obtained. The intensity dependence of two-photon absorption coefficients is presented. The dependence determines the boundary of the influence of high-order nonlinearities on the nonlinear transmittance of the samples. The mechanisms of optical limitation exhibited by sols, specifically, two-photon absorption, nonlinear refraction, and nonlinear scattering are discussed.

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