1,720,994 research outputs found
Optical Bloch-mode-induced quasi phase matching of quadratic interactions in one-dimensional photonic crystals
No full textWe examine in detail the quasi-phase-matching process obtained as a stationary modulation of the fundamental field at the band edge of a finite one-dimensional photonic crystal. The treatment is carried out in terms of the structure Bloch waves and fully explains the behavior of second-harmonic generation in the grating. An integrated microstructured AlGaAs mesa waveguide is proposed that gives efficient second-harmonic and difference-frequency generation in virtue of the combined presence of a periodic modulation of the fundamental-field amplitude and of the photonic bandgap edge
Optical Bloch-mode-induced quasi phase matching of quadratic interactions in one-dimensional photonic crystals
No full textLaser-Assisted Etching of EagleXG Glass by Irradiation at Low Pulse-Repetition Rate
Full text linkFemtosecond laser micromachining is becoming an established technique for the fabrication of complex three-dimensional structures in glass. The combination of laser writing and chemical etching increases the technique versatility by allowing the fabrication of hollow structures within the bulk material. The possibility to encompass both optical and fluidic components in a single substrate allows us to realize optofluidic devices usable in several application fields. Here, we present new investigations of laser-assisted etching in Eagle XG glass showing good etching conditions at low repetition rates, where thermal effects can be neglected, and low irradiation speeds, which allow for complex microchannel network formation
Editorial for the Special Issue on New Trends and Applications in Femtosecond Laser Micromachining
Full text linkFemtosecond laser micromachining is becoming an established fabrication technique for transparent material processing in three dimensions [...]
Validation and perspectives of a femtosecond laser fabricated monolithic optical stretcher
No full textThe combination of high power laser beams with microfluidic
delivery of cells is at the heart of high-throughput, single-cell analysis and
disease diagnosis with an optical stretcher. So far, the challenges arising
from this combination have been addressed by externally aligning optical
fibres with microfluidic glass capillaries, which has a limited potential for
integration into lab-on-a-chip environments. Here we demonstrate the
successful production and use of a monolithic glass chip for optical
stretching of white blood cells, featuring microfluidic channels and optical
waveguides directly written into bulk glass by femtosecond laser pulses.
The performance of this novel chip is compared to the standard capillary
configuration. The robustness, durability and potential for intricate flow
patterns provided by this monolithic optical stretcher chip suggest its use for
future diagnostic and biotechnological applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Characterization of conical emission of light filaments in media with anomalous dispersion
No full textConical emission featuring a diminishing emission angle with increasing wavelength detuning is observed in ultrashort light filaments in fused silica at a carrier wavelength with anomalous dispersion. In the measured angularly resolved spectrum of the filament, this conical emission appears as an elliptical, or O-like, structure that fits quantitatively to the elliptical spectrum of gain in the Kerr-driven spatiotemporal instability of nonlinear plane wave
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