Search results for "Length"
showing 10 items of 2188 documents
All-Optical frequency Shifter in a Periodically Poled Lithium Tantalate Waveguide
2011
A frequency shifting device is fabricated and tested in a congruent Lithium Tantalate waveguide. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained, demonstrating a two-stage parametric conversion.
Resonant and thermal changes of refractive index in a heavily doped erbium fiber pumped at wavelength 980 nm
2004
We report a theoretical and experimental study of the refractive index variation in a heavily doped erbium silica fiber within the spectral range 1500-1580 nm under the pumping at the wavelength 980 nm. The two main contributions in the refractive index change are addressed the resonant part determined by the saturation effect in the fiber and the thermal part stemming from the fiber heating due to the excited-state absorption and Stokes losses. We demonstrate that the thermal contribution in the resultant refractive index change is a notable value, which is the feature of erbium fibers with a high concentration of erbium ions.
Multioctave midinfrared supercontinuum generation in suspended-core chalcogenide fibers
2014
An As2S3 fiber-based supercontinuum source that covers 3500 nm, extending from near visible to the midinfrared, is successfully reported by using a 200-fs-pulsed pump with nJ-level energy at 2.5 μm. The main features of our fiber-based source are two-fold. On the one hand, a low-loss As2S3 microstructured optical fiber has been fabricated, with typical attenuation below 2 dB/m in the 1-4 μm wavelength range. On the other hand, a 20-mm-long microstructured fiber sample is sufficient to enable a spectral broadening, spreading from 0.6 to 4.1 μm in a 40 dB dynamic range.
Microstructured chalcogenide optical fibers from As2S3 glass: towards new IR broadband sources
2010
Made available in DSpace on 2013-08-28T14:12:29Z (GMT). No. of bitstreams: 1 WOS000285749500124.pdf: 1017839 bytes, checksum: f517fd8ef33fd56d66b9ccda9dc4d0f3 (MD5) Made available in DSpace on 2013-09-30T19:22:53Z (GMT). No. of bitstreams: 2 WOS000285749500124.pdf: 1017839 bytes, checksum: f517fd8ef33fd56d66b9ccda9dc4d0f3 (MD5) WOS000285749500124.pdf.txt: 33157 bytes, checksum: 1ca2ac713bf6024674249abf58520bcb (MD5) Previous issue date: 2010-12-06 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:34:00Z No. of bitstreams: 2 WOS000285749500124.pdf: 1017839 bytes, checksum: f517fd8ef33fd56d66b9ccda9dc4d0f3 (MD5) WOS000285749500124.pdf.txt: 33157 bytes,…
Strong infrared spectral broadening in low-loss As-S chalcogenide suspended core microstructured optical fibers
2010
Made available in DSpace on 2013-08-28T14:10:10Z (GMT). No. of bitstreams: 1 WOS000275454100017.pdf: 273411 bytes, checksum: da2aeaea61ab57013d39ecf2456466e3 (MD5) Made available in DSpace on 2013-09-30T19:22:36Z (GMT). No. of bitstreams: 2 WOS000275454100017.pdf: 273411 bytes, checksum: da2aeaea61ab57013d39ecf2456466e3 (MD5) WOS000275454100017.pdf.txt: 34647 bytes, checksum: b4efba760b21442eba43e7096f213b3e (MD5) Previous issue date: 2010-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:33:52Z No. of bitstreams: 2 WOS000275454100017.pdf: 273411 bytes, checksum: da2aeaea61ab57013d39ecf2456466e3 (MD5) WOS000275454100017.pdf.txt: 34647 bytes, ch…
Pentacyanopropenide group as ligand in organometallic chemistry. Crystal structure and electrochemical studies of (Et4N)[W(CO)5{(C(CN)2C(CN)C(CN)2}]
1999
Abstract The title complex has been obtained by reaction of the tetraethylammonium pentacyanopropenide with tungsten hexacarbonyl in acetone. Its crystal structure involves discrete [W(CO)5{C3(CN)5}]− anions in which the organic fragment is N-coordinated via one of the nitrogen atoms of a cyano group borne by one of the terminal carbon atoms of the allylic skeleton. The anion presents a distorted octahedral coordination with a W–N bond length [2.168(5) A] considerably longer than the W–C bond lengths [cis-W–C in the range 1.998(7)–2.068(4) A; trans-W–C 1.962(7) A]. Cyclic voltammograms of this complex, recorded in CH2Cl2 and CH3CN (Bu4NPF6 0.1 M), display a quasi-reversible reduction and ir…
Ab initio molecular orbital study of the substituent effect on ammonia and phosphine–borane complexes
2004
Abstract The complexation energies of H 3 BXH 3− n F n ( X =N, P; n =0–3) and the proton affinities of XH 3– n F n compounds have been investigated at the G2(MP2) level of theory. The G2(MP2) results show that the phosphine complexes are more stable than the corresponding ammonia ones. Increasing fluorine substitution on nitrogen atom reduces both the basicity of NH 3− n F n and the stability of ammonia complexes. For the phosphine complexes, the successive fluorine substitution on the phosphine increase the stability of H 3 BPH 3− n F n complexes although the reduction of the basicity of the PH 3– n F n ligands with this substitution. The NBO partitioning scheme shows that the stability of…
Plasmonic and diffractive nanostructures for light trapping—an experimental comparison
2015
Metal nanoparticles and diffractive nanostructures are widely studied for enhancing light trapping efficiency in thin-film solar cells. Both have achieved high performance enhancements, but there are very few direct comparisons between the two. Also, it is difficult to accurately determine the parasitic absorption of metal nanoparticles. Here, we assess the light trapping efficiencies of both approaches in an identical absorber configuration. We use a 240 nm thick amorphous silicon slab as the absorber layer and either a quasi-random supercell diffractive nanostructure or a layer of self-assembled metal nanoparticles for light trapping. Both the plasmonic and diffractive structures strongly…
High-efficiency silicon-compatible photodetectors based on Ge quantum dots
2011
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 Amer…
In vitro evaluation of the ability of three apex locators to determine the working length during retreatment.
2005
The purpose of this in vitro study was to evaluate the accuracy of three apex locators in determining the working length during the retreatment process. Twenty extracted single-rooted human teeth with mature apices were used in this study. The root canal length of each tooth was measured placing a #15 file until the tip was visible at the apical foramen. The direct visual measurement was reduced by 0.5 mm and recorded. The root canals were instrumented and filled to the direct visual measurement using lateral compaction technique. After 7 days the teeth were retreated using three apex locators: ProPex, NovApex, and Root ZX, for determining the retreatment working length. Afterward, comparis…