501 research outputs found
Field Localization and Enhancement of Phase Locked Second and Third Harmonic Generation in Absorbing Semiconductor Cavities
We predict and experimentally observe the enhancement by three orders of
magnitude of phase mismatched second and third harmonic generation in a GaAs
cavity at 650nm and 433nm, respectively, well above the absorption edge. Phase
locking between the pump and the harmonics changes the effective dispersion of
the medium and inhibits absorption. Despite hostile conditions the harmonics
become localized inside the cavity leading to relatively large conversion
efficiencies. Field localization plays a pivotal role and ushers in a new class
of semiconductor-based devices in the visible and UV ranges
Mutations in the EXT1 and EXT2 genes in Spanish patients with multiple osteochondromas
Multiple osteochondromas is an autosomal dominant skeletal disorder characterized by the formation of multiple cartilage-capped tumours. Two causal genes have been identified, EXT1 and EXT2, which account for 65% and 30% of cases, respectively. We have undertaken a mutation analysis of the EXT1 and EXT2 genes in 39 unrelated Spanish patients, most of them with moderate phenotype, and looked for genotype-phenotype correlations. We found the mutant allele in 37 patients, 29 in EXT1 and 8 in EXT2. Five of the EXT1 mutations were deletions identified by MLPA. Two cases of mosaicism were documented. We detected a lower number of exostoses in patients with missense mutation versus other kinds of mutations. In conclusion, we found a mutation in EXT1 or in EXT2 in 95% of the Spanish patients. Eighteen of the mutations were novel.Fil: SarriĂłn, P.. Universidad de Barcelona; EspañaFil: Sangorrin, A.. Hospital Sant Joan de DĂ©u; EspañaFil: Urreizti, R.. Universidad de Barcelona; EspañaFil: Delgado, MarĂa Andrea. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de CĂłrdoba; ArgentinaFil: Artuch, R.. Hospital Sant Joan de DĂ©u; EspañaFil: Martorell, L.. Hospital Sant Joan de DĂ©u; EspañaFil: Armstrong, J.. Hospital Sant Joan de DĂ©u; EspañaFil: Anton, J.. Hospital Sant Joan de DĂ©u; EspañaFil: Torner, F.. Hospital Sant Joan de DĂ©u; EspañaFil: Vilaseca, M. A.. Hospital Sant Joan de DĂ©u; EspañaFil: Nevado, J.. Hospital Universitario La Paz; EspañaFil: Lapunzina, P.. Hospital Universitario La Paz; EspañaFil: Asteggiano, Carla Gabriela. Universidad Nacional de CĂłrdoba; Argentina. Universidad CatĂłlica de CĂłrdoba; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Balcells, S.. Universidad de Barcelona; EspañaFil: Grinberg, D.. Universidad de Barcelona; Españ
Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials
© 2018 [Optical Society of America]. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. This method relies on the analysis of the wave-dependent spatial distribution of the second harmonic, in the plane perpendicular to the optical axis in combination with numerical simulations. We apply this technique to the characterization of two different media, Calcium Barium Niobate and Strontium Barium Niobate, with drastically different statistical distributions of ferroelectric domains.Peer ReviewedPostprint (published version
Cavity solitons in bidirectional lasers
We show theoretically that a broad area bidirectional laser with slightly
different cavity losses for the two counterpropagating fields sustains cavity
solitons (CSs). These structures are complementary, i.e., there is a bright
(dark) CS in the field with more (less) losses. Interestingly, the CSs can be
written/erased by injecting suitable pulses in any of the two
counterpropagating fields.Comment: 4 figure
Optics of Astigmatism and Retinal Image Quality
In the first part of this chapter, the optical condition of astigmatism is defined. The main causes and available classifications of ocular astigmatism are briefly described. The most relevant optical properties of image formation in an astigmatic eye are analysed and compared to that of an emmetropic eye and an eye with spherical ametropia. The spectacle prescription and axis notation for astigmatism are introduced, and the correction of astigmatism by means of lenses is briefly described.
The formation of the retinal image for extended objects and the related blurring are also analysed, and the real limits of tolerance of uncorrected astigmatism are provided. Simulations of retinal images in astigmatic eyes, obtained by means of commercial optical design software, are also presented.
Finally, the clinical assessment of retinal image quality by means of wavefront aberrometry and double-pass systems in eyes with astigmatism is presented, and current trends in research related to this topic are highlighted.Peer ReviewedPostprint (published version
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