New Opportunities in Lead Selenide Nanolayers

2013 ◽  
Vol 815 ◽  
pp. 473-477 ◽  
Author(s):  
Arif M. Pashaev ◽  
Omar I. Davarashvili ◽  
Megi I. Enukashvili ◽  
Zaira G. Akhvlediani ◽  
Revaz G. Gulyaev ◽  
...  
Keyword(s):  
Optical Transmission ◽  
Lead Selenide ◽  
Layer Growth ◽  
Transmission Spectra ◽  
High Concentration ◽  
Layer Growth Rate ◽  
Fabry Perot ◽  
Free Current ◽  
Gap Width ◽  
Forbidden Gap

The article deals with the peculiarities of creation of effective negative pressure and the increase in the forbidden gap width in PbSe nanolayers. The dielectric state that maybe realized under these conditions and their appropriate doping can be considered as a new resource in lead selenide nanolayers. The increasing of the tangential lattice constant with higher growth temperature and layer growth rate confirms this consideration. When determining the forbidden gap width, the optical transmission spectra were processed by a model of the Fabry-Perot interferometer, and, at high concentration of free current carriers, the absorption on them and their degeneracy were taken into consideration.

On the Structural and Optical Properties of Lead Selenide Nanolayers

2014 ◽  
Vol 1025-1026 ◽  
pp. 831-836 ◽  
Author(s):  
Arif M. Pashaev ◽  
Omar I. Davarashvili ◽  
Megi I. Enukashvili ◽  
Zaira G. Akhvlediani ◽  
Larisa P. Bychkova ◽  
...  
Keyword(s):  
Optical Transmission ◽  
Lead Selenide ◽  
Transmission Spectra ◽  
Structural And Optical Properties ◽  
Total Contribution ◽  
X Ray ◽  
Optical Transmission Spectra ◽  
The Given ◽  
Gap Width ◽  
Forbidden Gap

It was revealed that, according to the analysis by the half-width of the X-ray lines of reflection planes (200) and (600), the sizes of subgrains in the lead selenide nanolayer ~70 nm thick made up 30-45 nm. Disorientation between the subgrains of the order of the ten thousandth of a minute and the deformation (strain) in the layer was determined by the mismatch between the layer and the substrate. It is shown that the forbidden gap width Eg of the same PbSe nanolayer determined by analyzing the optical transmission spectra by two types of straightening f (hν) and (hν)2=f (hν) coincided and made up 0.445 eV, which exceeded Eg of the unstrained PbSe layer by 0.16 eV. The total contribution of quantum effects at the given subgrain sizes and degeneracy of current carriers is less than 0.03 eV, and generally the change in the forbidden gap width was associated with deformation. Key words: dispersion, deformation, disorientation between subgrains, optical transmission, forbidden gap width.

scholarly journals Extraordinary Optical Transmission by Hybrid Phonon–Plasmon Polaritons Using hBN Embedded in Plasmonic Nanoslits

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1567
Author(s):  
Shinpei Ogawa ◽  
Shoichiro Fukushima ◽  
Masaaki Shimatani
Keyword(s):  
Optical Transmission ◽  
Hexagonal Boron Nitride ◽  
Incident Angle ◽  
Optical Filters ◽  
Extraordinary Optical Transmission ◽  
Light Manipulation ◽  
Rigorous Coupled Wave Analysis ◽  
Fabry Perot ◽  
Hyperbolic Dispersion ◽  
Rigorous Coupled Wave

Hexagonal boron nitride (hBN) exhibits natural hyperbolic dispersion in the infrared (IR) wavelength spectrum. In particular, the hybridization of its hyperbolic phonon polaritons (HPPs) and surface plasmon resonances (SPRs) induced by metallic nanostructures is expected to serve as a new platform for novel light manipulation. In this study, the transmission properties of embedded hBN in metallic one-dimensional (1D) nanoslits were theoretically investigated using a rigorous coupled wave analysis method. Extraordinary optical transmission (EOT) was observed in the type-II Reststrahlen band, which was attributed to the hybridization of HPPs in hBN and SPRs in 1D nanoslits. The calculated electric field distributions indicated that the unique Fabry–Pérot-like resonance was induced by the hybridization of HPPs and SPRs in an embedded hBN cavity. The trajectory of the confined light was a zigzag owing to the hyperbolicity of hBN, and its resonance number depended primarily on the aspect ratio of the 1D nanoslit. Such an EOT is also independent of the slit width and incident angle of light. These findings can not only assist in the development of improved strategies for the extreme confinement of IR light but may also be applied to ultrathin optical filters, advanced photodetectors, and optical devices.

The flow over a backward-facing step under controlled perturbation: laminar separation

1992 ◽  
Vol 238 ◽  
pp. 73-96 ◽  
Author(s):  
M. A. Z. Hasan
Keyword(s):  
Shear Layer ◽  
Low Frequency ◽  
Layer Growth ◽  
Stream Velocity ◽  
Backward Facing Step ◽  
Laminar Separation ◽  
Vortex Merging ◽  
Layer Growth Rate ◽  
Merging Process ◽  
Layer Flow

The flow over a backward-facing step with laminar separation was investigated experimentally under controlled perturbation for a Reynolds number of 11000, based on a step height h and a free-stream velocity UO. The reattaching shear layer was found to have two distinct modes of instability: the ‘shear layer mode’ of instability at Stθ ≈ 0.012 (Stθ ≡ fθ/UO, θ being the momentum thickness at separation and f the natural roll-up frequency of the shear layer); and the ‘step mode’ of instability at Sth ≈ 0.185 (Sth ≡ fh/U0). The shear layer instability frequency reduced to the step mode one via one or more stages of a vortex merging process. The perturbation increased the shear layer growth rate and the turbulence intensity and decreased the reattachment length compared to the unperturbed flow. Cross-stream measurements of the amplitudes of the perturbed frequency and its harmonics suggested the splitting of the shear layer. Flow visualization confirmed the shear layer splitting and showed the existence of a low-frequency flapping of the shear layer.

Depth of glass poling - via optical transmission spectra

Optik ◽  
2021 ◽  
pp. 167600
Author(s):  
Ekaterina Babich ◽  
Dmitrii Raskhodchikov ◽  
Ekaterina Lubyankina ◽  
Andrey Lipovskii
Keyword(s):  
Optical Transmission ◽  
Transmission Spectra ◽  
Optical Transmission Spectra

Structure and optical transmission spectra of ZnS–SiO2 nanocomposite films deposited at low temperatures

2015 ◽  
Vol 49 (10) ◽  
pp. 1327-1331 ◽  
Author(s):  
P. N. Krylov ◽  
R. M. Zakirova ◽  
I. A. Knyazev ◽  
N. V. Kostenkov ◽  
E. A. Romanov ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Optical Transmission ◽  
Nanocomposite Films ◽  
Transmission Spectra ◽  
Optical Transmission Spectra

Are the Temperature Sensors Based on Chalcogenide Glass Possible?

2013 ◽  
Vol 200 ◽  
pp. 316-320
Author(s):  
Mykhaylo Shpotyuk ◽  
Dmytro Chalyy ◽  
Oleh Shpotyuk ◽  
Mihail Iovu ◽  
Andrzej Kozdras ◽  
...  
Keyword(s):  
Chalcogenide Glasses ◽  
Optical Transmission ◽  
Optical Band Gap ◽  
Temperature Sensors ◽  
Sensitivity Index ◽  
Transmission Spectra ◽  
Scanning Calorimetry ◽  
Linear Character ◽  
Optical Transmission Spectra ◽  
Principal Possibility

Principal possibility of the using of chalcogenide glasses (on the example of Ge18As18Se64) as active media for temperature sensors is considered in this work. Differential scanning calorimetry testing of the investigated glasses shown that 2 years of natural storage does not lead to the drift of their DSC-parameters (glass transition temperature and endothermic peak area). Investigation of the temperature dependence of optical transmission spectra shows the linear character of optical band-gap changes with a temperature. Temperature sensitivity index β for Ge18As18Se64 is estimated to be equal to the ~1.2·10-3 eV/°C.

Facile synthesis of silica–titania core–shell microsphere and their optical transmission spectra

2013 ◽  
Vol 110 ◽  
pp. 260-263 ◽  
Author(s):  
Huihua Huang ◽  
Aihua Sun ◽  
Jianfei Zhang ◽  
Biao Wang ◽  
Chengyi Chu ◽  
...  
Keyword(s):  
Optical Transmission ◽  
Core Shell ◽  
Transmission Spectra ◽  
Facile Synthesis ◽  
Optical Transmission Spectra
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