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Ultrafast optically induced reflectivity switching at a gallium-silica interface
No full textIt was reported recently that the reflectivity of a gallium-silica interface held close to, but below, the gallium melting point of 29.8 C can be changed significantly (>40%) by light over a very broad spectral range 400 - 1600 nm. The effect has been attributed to a surface-assisted phase transition from the stable α-gallium phase to a phase of metallic nature. In this paper we present the results on the ultrafast switching dynamics of a gallium-silica interface
Gigantic broadband optical nonlinearity in gallium films deposited by ultrafast laser ablation
No full textGigantic broadband optical nonlinearity in gallium films deposited by ultrafast laser ablation
No full textGallium-Silica interfaces have emerged as a new type of structure that combines a strong nonlinearity [1] with picosend switching-on time [2]. Here we report that the optical nonlinearity of gallium films deposited on fused silica by ultrafast pulsed laser ablation is very broadband, spanning from 480 nm to 810 nm
Light-induced metallization in laser-deposited gallium films
No full textWe have found that mirrors prepared upon silica glass by ultrafast pulsed laser deposition of elemental gallium show a highly reproducible and fully reversible light-induced reflectivity increase. The effect is explained as being due to nonthermal light-induced metallization of gallium at the interface
The light-induced structural phase transition in confining gallium and its photonic applications
No full textWe report on a study of the dynamics of a recently discovered light-induced, surface-assisted, structural phase transition from a common orthorhombic phase of α-gallium to a highly reflective phase that occurs at temperatures just below the metal's bulk melting point (30 °C). It is fully reversible with dynamics occurring on a nanosecond/microsecond time scale and can be stimulated by very low-intensity radiation, typically 10-5 W/µm². The two gallium phases involved have significantly different optical properties and this difference gives rise to a gigantic optical nonlinearity, χ(3) ~ 1 esu, that offers tremendous new opportunities for controlling light with light. The microscopic model of the effect is discussed
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
Gigantic optical nonlinearity in laser-deposited gallium films on the verge of a structural phase transition
No full textGallium/silica interfaces prepared by ultrafast pulsed laser deposition have excellent optical qualities and structural stability. They show a gigantic optical nonlinearity in the visible and infrared, up to 1800 nm, which reaches χ3) ~ 1 esu
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
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