Revision of the genus Tapholeon Wells, 1967 (Copepoda, Harpacticoida, Laophontidae)

To date, only two species are known in the laophontid genus Tapholeon Wells, 1967 (Copepoda, Harpacticoida). In the present contribution, a redescription of the type species T. ornatus Wells, 1967, based on the type material, is provided. Furthermore, two new species are described from the coast of Kenya, T. inconspicuus sp. nov. and T. tenuis sp. nov. Two species, formerly attributed to Asellopsis Brady and Robertson, 1873 (namely A. arenicola Chappuis, 1954 and A. chappuisius Krishnaswamy, 1957), are allocated to Tapholeon based on the absence of sexual dimorphism in the swimming legs P2-P4. The former of the two species is redescribed based on additional material from the Comoros. An updated generic diagnosis and a key to the six species of Tapholeon are included

Sur les correspondances entre bivecteurs et spineurs simples et la description corpusculaire des ondes électromagnétiques

Des conditions de réalité et de réciprocité permettent de définir une correspondance invariante entre un bivecteur isotrope réel et un couple de spineurs simples particuliers. Une telle correspondance pourrait traduire une équivalence objective entre un photon-onde plane et un couple de corpuscules de Dirac de masse nulle, de densités de vecteur-courant égales, de densités de moments électromagnétiques opposés, de densité de spin nulle, dont chacun est confondu avec une « lacune associée »

Une forme spinorielle des équations de l'électromagnétisme

This paper contains a description of the general electromagnetic field and a transcription of the Maxwell-Lorentz equations in terms of first-rank spinors in space-time : Any real bivector is the dual (or orthocomplementary) of the sum of the electromagnetic densities determined by two spinors compounded with their respective " lacunal ". The general solution of the Maxwell- Lorentz equations is of this form, its two generating spinors being solutions of suitable equations. In vacuum, and for a large classe of fields, these two spinors are solutions, suitably interrelated, of the Dirac equation for zero-mass corpuscules. (These results were stated, without proofs, in C..R. Acad. Se., 29 octobre, 1956, 243, 1287.)Il s'agit d'une description d'un champ électromagnétique general, et d'une transcription des équations de Maxwell-Lorentz, en termes de spineurs du premier rang, dans l'espace-temps : Tout bivecteur réel est le dual de la somme des densités de moment électromagnétique de deux spineurs, confondus avec leurs "lacunes" respectives. La solution générale des equations de Maxwell-Lorentz est de cette forme, ses deux spineurs générateurs étant solutions d'équations convenables. Dans le vide, et pour une classe étendue de champs, ces deux spineurs sont des solutions, convenablement liées, de l'équation de Dirac à masse nulle. (Ces resultats ont ete énoncés, sans preuves, aux C. R. Acad. Sc., 29 octobre 1956, 243, p. 1287.

Design of rare-earth doped chalcogenide microresonators for biosensing in Mid-IR

International audienceIn this paper some preliminary results pertaining to the design and fabrication of rare-earth doped chalcogenide microresonators for lasing in mid-infrared (Mid-IR) wavelength range are illustrated. The unique properties of chalcogenide glass and the Whispering Gallery Mode (WGM) resonances make possible to obtain light emission via rare-earth transitions at long wavelengths. As example, a light source based on chalcogenide glass doped with Er3+ is investigated via a home-made numerical model based on the coupled mode theory and solving the rare-earth rate equations. A number of promising applications in different areas such as biology, molecular spectroscopy and environmental monitoring are feasible. © 2016 IEEE

Sub-MHz linewidth UV laser diode for metrological applications

International audienc

Sub-20 kHz low frequency noise near ultraviolet miniature external cavity laser diode

We present a compact InGaN fiber Bragg grating (FBG) semiconductor laser diode operating below 400 nm in the single-mode emission regime. This compact coherent laser source exhibits an intrinsic linewidth of 14 kHz in the near-UV range and a side-mode suppression ratio reaching up to 40 dB accompanied by a mW-level output power. Furthermore, the properties of the FBG, including its central wavelength, bandwidth, and reflectivity, can be readily customized to fulfill specific requirements. As a result, the small footprint design of this laser is compatible with integration into a standard butterfly package to ease the lab-to-market technology transfer. The combination of low frequency noise and fibered output signal positions these FBG laser systems as strong candidates for hybridization with integrated photonic platforms tailored for quantum information processing and metrology