Search results for "Generation"
showing 10 items of 3050 documents
Optimized blue light generation in optically contacted walk-off compensated RbTiOAsO4 and KTiOP1−yAsyO4
1999
Abstract We study type II 1.32 μm second harmonic generation (SHG) in a RbTiOAsO 4 optically contacted walk-off compensated device. The reduction of the effective walk-off angle by a factor of 3.7 with respect to KTiOPO 4 for the same interaction leads to an enhancement by a factor of 10 of the conversion efficiency. A model is proposed for both type I and type II SHG in such a structure. The angular tuning curve is a multi-peaked one, as predicted by the model. The enhancement of the SHG conversion efficiency allows us to optimize the generation of blue laser light at 440 nm: a specially designed KTiOP 0.98 As 0.02 O 4 solid solution crystal achieves angular non-critical phase matching at …
Parametric conversion in micrometer and sub-micrometer structured ferroelectric crystals by surface poling
2012
We report on recent technological improvements concerning nonlinear patterning of lithium niobate and lithium tantalate in the micrometer and submicrometer scales using surface periodic poling for ferroelectric domain inversion. The fabricated samples were employed for frequency doubling via quasiphase-matching both in bulk and guided wave geometries, including forward and backward configurations and wavelength conversion in bands C and L. We also investigated short-period quasiperiodic samples with randomly distributed mark-to-space ratios.
Second harmonic generation in coupled LiNbO3 waveguides by reverse-proton exchange
2003
We demonstrate second harmonic generation of a near-infrared pump in a nonlinearly coupled system formed by longitudinally uniform proton- and reverse-proton-exchanged LiNbO/sub 3/ planar waveguides. Phase- and mode-matched transverse electric (TE/sub 0/) frequency doubling into transverse magnetic higher order guided modes is achieved through temperature control, in agreement with the model.
Development of two-color resonance ionization scheme for Th using an automated wide-range tunable Ti:sapphire laser system
2018
Two-color resonance ionization schemes of Th were investigated by an automated wide-range tunable, grating-assisted Ti:Sa laser system with intracavity SHG option. A two-color ionization scheme via autoionizing state (1st step: 372.049 nm and 2nd step: 401.031 nm) was developed and its relative efficiency was lower by factor of three compared to a known three color scheme. peerReviewed
Performance analysis of single cell solid oxide fuel cells
2017
Solid oxide fuel cells (SOFCs) are a class of fuel cells operating on high temperatures which have the potential to become one of the efficient and cost effective system for direct conversion of a wide variety of fuels to electricity. For proper operation of SOFCs, evaluation of cell stability and optimization of fuel utilization is of paramount importance. In this paper, we have performed experiments to obtain current-voltage (I–V) characteristics by using three different Hydrogen (H 2 ) flow rates(100 ml/min, 150 ml/min and 200 ml/min). Furthermore, we perform oxidation and reduction (redox) cycles to determine how many redox cycles a SOFC can withstand without cracking the cell which we …
Regenerable ZnO/GaAs Bulk Acoustic Wave Biosensor for Detection of Escherichia coli in “Complex” Biological Medium
2021
A regenerable bulk acoustic wave (BAW) biosensor is developed for the rapid, label-free and selective detection of Escherichia coli in liquid media. The geometry of the biosensor consists of a GaAs membrane coated with a thin film of piezoelectric ZnO on its top surface. A pair of electrodes deposited on the ZnO film allows the generation of BAWs by lateral field excitation. The back surface of the membrane is functionalized with alkanethiol self-assembled monolayers and antibodies against E. coli. The antibody immobilization was investigated as a function of the concentration of antibody suspensions, their pH and incubation time, designed to optimize the immunocapture of bacteria. The perf…
3D Bioprinting for Vascularized Tissue-Engineered Bone Fabrication
2020
Vascularization in bone tissues is essential for the distribution of nutrients and oxygen, as well as the removal of waste products. Fabrication of tissue-engineered bone constructs with functional vascular networks has great potential for biomimicking nature bone tissue in vitro and enhancing bone regeneration in vivo. Over the past decades, many approaches have been applied to fabricate biomimetic vascularized tissue-engineered bone constructs. However, traditional tissue-engineered methods based on seeding cells into scaffolds are unable to control the spatial architecture and the encapsulated cell distribution precisely, which posed a significant challenge in constructing complex vascul…
Second-harmonic generation in Langmuir–Blodgett monolayers of stilbazium salt and phenylhydrazone dyes
1988
The second-order nonlinear optical susceptibilities χ(2) of several phenylhydrazone and stilbazium salt dyes in Langmuir–Blodgett monolayers have been determined from second-harmonic-generation measurements. Three of the substances demonstrated χ(2) values greater than 10−6 electrostatic units, although two of the three did not absorb light significantly at the second-harmonic wavelength.
Scanning near-field optical microscopy (SNOM) of lithium niobate aperiodically poled during growth
2007
In the present work, aperiodically poled lithium niobate (APPLN) was grown, along the a-axis, by the off-centred Czochraski method. The domain formation has been triggered by rare earth doping, using in this case Er3+ and Yb3+ ions. The growth conditions were selected in order to obtain a modulated domain distribution. SNOM measurements have been performed with a Nanonics Imaging Ltd model MultiView 200 TM working in non-contact tapping mode.
Optical tuning of dielectric nanoantennas for thermo-optically reconfigurable nonlinear metasurfaces
2021
We demonstrate optically tunable control of second-harmonic generation in all-dielectric nanoantennas: by using a control beam that is absorbed by the nanoresonator, we thermo-optically change the refractive index of the radiating element to modulate the amplitude of the second-harmonic signal. For a moderate temperature increase of roughly 40 K, modulation of the efficiency up to 60% is demonstrated; this large tunability of the single meta-atom response paves the way to exciting avenues for reconfigurable homogeneous and heterogeneous metasurfaces.