Search results for "Second harmonic generation"
showing 10 items of 20 documents
Effect of sodium to barium substitution on the space charge implementation in thermally poled glasses for nonlinear optical applications
2009
Thermally poled niobium borophosphate glasses in the system 0.55(0.95-y) NaPO{sub 3}+y/2 Ba(PO{sub 3}){sub 2}+0.05Na{sub 2}B{sub 4}O{sub 7})+0.45Nb{sub 2}O{sub 5} were investigated for second order optical nonlinear (SON) properties. Bulk glasses were studied by Raman spectroscopy, thermal analysis, optical and dielectric measurements. The sodium to barium substitution does not lead to significant changes in optical properties, crystallization of glasses and coordination environment of polarizable niobium atoms. However, the ionic conductivity decreases drastically with the increase of barium concentration. Secondary ion mass spectroscopy has been used to determine the element distribution …
High-pressure phase ofLaPO4studied by x-ray diffraction and second harmonic generation
2016
The pressure-induced phase transition of monazite-type ${\mathrm{LaPO}}_{4}$ at $\ensuremath{\approx}26$ GPa is studied by single-crystal x-ray diffraction and second harmonic generation (SHG) up to 31 GPa. The structure of the postmonazite phase of ${\mathrm{LaPO}}_{4}$ has been obtained and it is shown that it corresponds to a post-barite-type structure with an acentric space group $P{2}_{1}{2}_{1}{2}_{1}$. A strong increase of the SHG signal at the transition confirms that the high-pressure polymorph is noncentrosymmetric. The phase transition involves a significant discontinuous decrease of the unit-cell volume by 6%, which is mainly due to a strong contraction of the $a$ lattice parame…
Generazione di Seconda Armonica per Quasi-Phase-Matching Random in Tantalato di Litio con Poling Periodico
2009
We experimentally observed and explained bulk Second Harmonic Generation via Random Quasi-Phase-Matching, derived from a periodically poled Lithium Tantalate sample with a randomly patterned mark-to-space-ratio.
Ferrocene-quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films
2016
The first example of a Y-shaped ferrocene quinoxaline derivative with a surprisingly high and stable second harmonic generation (SHG) response in composite polymeric films is reported. The interesting quadratic hyperpolarizability values of different substituted Y-shaped chromophores are also investigated in solution by the EFISH technique.
Chalcogenide Glasses Based on Germanium Disulfide for Second Harmonic Generation
2007
International audience; High second-order susceptibilities are created by thermal poling in bulk germanium disulfide based chalcogenide glasses. Experimental conditions of the poling treatment (temperature, voltage, time) were optimized for each glass composition. The second-order nonlinear signals were recorded by using the Maker fringes experiment and a second-order coefficient χ(2) up to 8 pm V-1 was measured in the Ge25Sb10S65 glass. This value is obtained using a simulation based on accurate knowledge of the thickness of the nonlinear layer. Two mechanisms are proposed to explain the creation of a nonlinear layer under the anode: the formation and the migration of charged defects towar…
Quadratic nonlinear optical parameters of 7% MgO-doped LiNbO3 crystal
2016
International audience; Pure and 7% MgO-doped lithium niobate (LiNbO3) single crystals were grown by the Czochralski technique. The shift of optical absorption edge in 7% MgO-doped crystal in direction of shorter wavelength compared to undoped crystal was observed. The second harmonic generation measurements of 7% MgO-doped LiNbO3 crystal were performed at room temperature by means of the rotational Maker fringe technique using Nd:YAG laser generating at 1064 nm in picoseconds regime. Experimentally obtained value of nonlinear optical coefficient d33 for 7% MgO-doped LiNbO3 was found to be less than for undoped crystal but higher than for 5% MgO-doped. I-type phase-matched second harmonic g…
Second-harmonic Generation Microscopy of Carbon Nanotubes
2012
We image an individual single-walled carbon nanotube (SWNT) by second-harmonic generation (SHG) and transmission electron microscopy and propose that SHG microscopy could be used to probe the handedness of chiral SWNTs.
Advanced microscopy analysis of the micro-nanoscale architecture of human menisci
2019
AbstractThe complex inhomogeneous architecture of the human meniscal tissue at the micro and nano scale in the absence of artefacts introduced by sample treatments has not yet been fully revealed. The knowledge of the internal structure organization is essential to understand the mechanical functionality of the meniscus and its relationship with the tissue’s complex structure. In this work, we investigated human meniscal tissue structure using up-to-date non-invasive imaging techniques, based on multiphoton fluorescence and quantitative second harmonic generation microscopy complemented with Environmental Scanning Electron Microscopy measurements. Observations on 50 meniscal samples extract…
Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV
2017
In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of …
Background-Free Second-Harmonic Generation Microscopy of Individual Carbon Nanotubes
2015
We use polarized second-harmonic generation (SHG) microscopy to investigate pristine air-suspended carbon nanotubes (CNT). We show that SHG originates from CNT chirality, allowing also different response for the two circular polarizations of fundamental light.