Measurements of the optical properties of liquid silicon and germanium using nanosecond time‐resolved ellipsometry

1987 ◽  
Vol 51 (5) ◽  
pp. 352-354 ◽  
Author(s):  
G. E. Jellison ◽  
D. H. Lowndes
Keyword(s):  
Optical Properties ◽  
Liquid Silicon ◽  
Time Resolved ◽  
Silicon And Germanium

scholarly journals Sulfophosphate Glass Doped with Er3+ and TiO2 Nanoparticles: Thermo-Optical Characterization by Photothermal Spectroscopy

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 115
Author(s):  
Zeinab Ebrahimpour ◽  
Humberto Cabrera ◽  
Fahimeh Ahmadi ◽  
Asghar Asgari ◽  
Joseph Niemela
Keyword(s):  
Optical Properties ◽  
Tio2 Nanoparticles ◽  
Refractive Index Change ◽  
Optical Path Length ◽  
Beam Deflection ◽  
Time Resolved ◽  
Tio2 Nps ◽  
Amorphous Glass ◽  
Laser Media ◽  
Materials Used

In this work, time-resolved thermal lens and beam deflection methods were applied to determine the thermo-optical properties of Er3+ doped sulfophosphate glass in which different concentrations of Titanium dioxide (TiO2) nanoparticles (NPs) were embedded. Thermal diffusivity (D), thermal conductivity (κ), and the temperature coefficient of the optical path length (ds/dT) were determined as a function of NPs concentrations. Moreover, the growth of TiO2 NPs inside the amorphous glass matrix was evidenced by Transmission Electron Microscopy (TEM) images as well as through optical effects such as refractive index change of the glass. The outcomes indicated relatively high values for D and κ as well as a low ds/dT as required for most optical components used for laser media. The addition of TiO2 NPs with concentration of dopants up to 0.6 mol% improved the optical properties of the glass samples but did not affect its thermal properties. The results indicate that the enhanced optical and thermal performance of the proposed co-doped glass fits the quality standards for materials used in photonic devices.

scholarly journals Impact of the ZnO buffer on the optical properties of GaN: time resolved micro-photoluminescence

1999 ◽  
Vol 59 (1-3) ◽  
pp. 163-167 ◽  
Author(s):  
A. Hoffmann ◽  
J. Holst ◽  
A. Kaschner ◽  
H. Siegle ◽  
J. Christen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Time Resolved

scholarly journals Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples

2001 ◽  
Vol 55 (10) ◽  
pp. 1368-1374 ◽  
Author(s):  
Rinaldo Cubeddu ◽  
Cosimo D'Andrea ◽  
Antonio Pifferi ◽  
Paola Taroni ◽  
Alessandro Torricelli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Industrial Applications ◽  
Nondestructive Monitoring ◽  
Nondestructive Measurement ◽  
Time Resolved ◽  
Mean Values ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
The Mean ◽  
Temporal Dispersion

Time-resolved reflectance has been used for the nondestructive measurement of optical properties in apples. The technique is based on the detection of the temporal dispersion of a short laser pulse injected into the probed medium. The time distribution of re-emitted photons interpreted with a solution of the diffusion equation yields the mean values of the absorption and reduced scattering coefficients of the medium. The proposed technique proved useful for the measurement of the absorption and scattering spectra of different varieties of apples, revealing the spectral shape of chlorophyll. No major variations were observed in the experimental data when the fruit was peeled, showing that the optical properties measured were those of the pulp. With this technique the change in chlorophyll absorption during storage and ripening could be followed. Finally, a compact prototype working at few selected wavelengths was designed and constructed, demonstrating potentialities of the technique for industrial applications.

Luminescence Properties of InGaN/GaN Green Light-Emitting Diodes with Si-Doped Graded Short-Period Superlattice

2021 ◽  
Vol 21 (11) ◽  
pp. 5648-5652
Author(s):  
ll-Wook Cho ◽  
Bom Lee ◽  
Kwanjae Lee ◽  
Jin Soo Kim ◽  
Mee-Yi Ryu
Keyword(s):  
Optical Properties ◽  
Decay Time ◽  
Stark Effect ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Time Resolved ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Short Period ◽  
Si Doped

The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

Lability of Stationary and Time-Resolved Optical Properties of the Conformationally Locked CFP Chromophore Derivative

2021 ◽  
Vol 47 (3) ◽  
pp. 784-787
Author(s):  
A. M. Bogdanov ◽  
D. A. Gorbachev ◽  
E. R. Zaitseva ◽  
A. Yu. Smirnov ◽  
N. S. Baleeva ◽  
...  
Keyword(s):  
Optical Properties ◽  
Time Resolved ◽  
Conformationally Locked

scholarly journals Synthesis, Surface Modification and Purification of Silicon and Germanium Quantum Dots for Biological Applications

2021 ◽  
Author(s):  
◽  
Amane Shiohara
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Silica Nanoparticles ◽  
Microemulsion System ◽  
Biological Applications ◽  
Silicon Quantum Dots ◽  
Surface Molecules ◽  
Silicon And Germanium ◽  
Germanium Quantum Dots ◽  
Oxygen Atoms

<p>Quantum dots have applications in biomedical fields such as bio-imaging and drug delivery systems. This thesis describes research on silicon and germanium nanoparticles (quantum dots) synthesis and surface modification for biological applications. Purification methods of these quantum dots were also explored. In chapter 6 the application of silica nanoparticles into dry eye diagnosis was studied. The purpose of this research is to contribute the application of nanotechnology into biological fields. The crystalinity of the quantum dots was characterised by Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction analysis (SAED). The molecules on the surface of the quantum dots were characterised by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR).  Silicon quantum dots were synthesised with a microemulsion system and various types of molecules were attached on the surface of the silicon quantum dots. However, some of the capping molecules which have oxygen atoms tend to form bonds between oxygen and silicon. Therefore, in the later chapter (chapter 4) various chemical reactions were conducted on the molecules attached to the silicon quantum dots. The silicon quantum dots were capped with diene molecules and one of the double bonds was left on the terminal end. The terminal end double bonds were converted to the functional groups which contain oxygen atoms to form peptide bonds. In this way it was confirmed that it can reduce the risk of oxygen atoms to be attached on the surface of the silicon quantum dots. The molecules on the surface of the silicon quantum dots were characterised mainly by FTIR and ¹H NMR. Optical properties and cyto-toxicity of these silicon quantum dots were also measured and analysed depending on the surface molecules.  Two synthetic approaches were taken to produce germanium quantum dots. The first approach was the microemulsion system at room temperature. Different combinations of the surfactant and capping molecules were tested. For the second approach, high temperature bench top system was applied. In this method the bio-friendly molecules which have high boiling points were chosen as capping agents. The surface molecules were characterised by FTIR spectroscopy.  In chapter 6 the synthesis of dye molecules conjugated silica nanoparticles was described. The purpose of this research is to produce biologically safe nanoparticles which can be applied in dry eye diagnosis. Three different dyes were used to conjugate with the silica nanoparticles. Only fluorescein isothiocyanate (FITC) succeeded in conjugating with the nanoparticles. Optical properties of this sample were measured and compared with the free dye molecule. Also the sample was applied in human eyes to analyse the tear film layer.  An overall conclusion and future plans for the research were given in the last chapter.In this chapter, ideas of overcoming the problems and improving the techniques conducted in the research were described.</p>

scholarly journals Time-resolved reflectance measurements on layered tissues with strongly varying optical properties

1995 ◽  
Author(s):  
Andreas H. Hielscher ◽  
Hanli Liu ◽  
Lihong V. Wang ◽  
Frank K. Tittel ◽  
Britton Chance ◽  
...  
Keyword(s):  
Optical Properties ◽  
Time Resolved ◽  
Reflectance Measurements
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