Coherent sources and techniques for chemical sensing using broadband mid-infrared light

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Few-cycle mid-infrared pulses from BaGa2GeSe6

BaGa2GeSe6 (BGGSe) is a newly developed nonlinear material that is attractive for ultrabroad frequency mixing and ultrashort pulse generation due to its comparably low dispersion and high damage threshold. A numerical study shows the material’s capacity for octave-spanning mid-infrared pulse generation up to 18 µm. In a first experiment, we show that a long crystal length of 2.6 mm yields a pulse energy of 21 pJ at 100 MHz with a spectral bandwidth covering 5.8 to 8.5 µm. The electric field of the carrier-envelope-phase stable pulse is directly measured with electro-optical sampling and reveals a pulse duration of 91 fs, which corresponds to sub-four optical cycles, thus confirming some of the prospects of the material for ultrashort pulse generation and mid-infrared spectroscopy.European Research Council (ERC Advanced Grant “TRANSFORMER” 788218, Proof of Concept Grant “miniX” 840010); H2020 Future and Emerging Technologies (“PETACom” 829153, FET-OPEN "OPTOlogic" 899794); Laserlab-Europe (EU-H2020 654148); Ministerio de Economía y Competitividad (Plan Nacional FIS2017-89536- P, “SeveroOchoa” SEV- 2015-0522); Agència deGestió d’Ajuts Universitaris i de Recerca (2017 SGR 1639); Fundación Cellex Barcelona; Centres de Recerca de Catalunya Programme / Generalitat de Catalunya; Alexander von Humboldt-Stiftung (FriedrichWilhelmBessel Prize).Peer ReviewedPostprint (published version

A revision of the early neotheropod genus <i>Sarcosaurus</i> from the Early Jurassic (Hettangian–Sinemurian) of central England

Neotheropoda represents the main evolutionary radiation of predatory dinosaurs and its oldest records come from Upper Triassic rocks (c. 219 Mya). The Early Jurassic record of Neotheropoda is taxonomically richer and geographically more widespread than that of the Late Triassic. The Lower Jurassic (upper Hettangian-lower Sinemurian) rocks of central England have yielded three neotheropod specimens that have been assigned to two species within the genus Sarcosaurus, S. woodi (type species) and S. andrewsi. These species have received little attention in discussions of the early evolution of Neotheropoda and recently have been considered as nomina dubia. Here, we provide a detailed redescription of one of these specimens (WARMS G667-690) and reassess the taxonomy and phylogenetic relationships of the genus Sarcosaurus. We propose that the three neotheropod specimens from the Early Jurassic of central England represent a single valid species, S. woodi. The second species of the genus, 'S. andrewsi', is a subjective junior synonym of the former. A quantitative phylogenetic analysis of early theropods recovered S. woodi as one of the closest sister-taxa to Averostra and provides new information on the sequence of character state transformations in the lead up to the phylogenetic split between Ceratosauria and Tetanurae.Fil: Ezcurra, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Butler, Richard J.. University of Birmingham; Reino UnidoFil: Maidment, Susannah C. R.. University of Birmingham; Reino Unido. Natural History Museum; Reino UnidoFil: Sansom, Ivan J.. University of Birmingham; Reino UnidoFil: Meade, Luke E.. University of Birmingham; Reino UnidoFil: Radley, Jonathan D.. University of Birmingham; Reino Unid

High-brightness seven-octave carrier envelope phase-stable light source

High-brightness sources of coherent and few-cycle-duration light waveforms with spectral coverage from the UV to the THz would offer unprecedented versatility and opportunities for a spectacular range of applications from bio-chemical sensing, to time-resolved and nonlinear spectroscopy, to attosecond light-wave electronics. Combinations of various sources with frequency conversion and supercontinuum generation can provide relatively large spectral coverage, but many applications require much broader spectral range and low-jitter synchronization for time-domain measurements. Here, we present a carrier-envelope-phase stable light source, seeded by a mid-IR frequency comb, with simultaneous spectral coverage across 7 optical octaves, from the UV (340 nm) into the THz (40,000 nm). Combining soliton self-compression and dispersive wave generation in an anti-resonant-reflection photonic crystal fibre with intra-pulse difference frequency generation in BaGa2GeSe6, the spectral brightness is 2-5 orders of magnitude above synchrotron sources. This enables high-dynamic-range spectroscopies and provides enticing prospects for attosecond physics and material sciences.Comment: 4 figure