The ArT\'eMiS wide-field submillimeter camera: preliminary on-sky performances at 350 microns

ArTeMiS is a wide-field submillimeter camera operating at three wavelengths simultaneously (200, 350 and 450 microns). A preliminary version of the instrument equipped with the 350 microns focal plane, has been successfully installed and tested on APEX telescope in Chile during the 2013 and 2014 austral winters. This instrument is developed by CEA (Saclay and Grenoble, France), IAS (France) and University of Manchester (UK) in collaboration with ESO. We introduce the mechanical and optical design, as well as the cryogenics and electronics of the ArTeMiS camera. ArTeMiS detectors are similar to the ones developed for the Herschel PACS photometer but they are adapted to the high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4 sub-arrays at 200 microns and 2x8 sub-arrays at 350 and 450 microns. We show preliminary lab measurements like the responsivity of the instrument to hot and cold loads illumination and NEP calculation. Details on the on-sky commissioning runs made in 2013 and 2014 at APEX are shown. We used planets (Mars, Saturn, Uranus) to determine the flat-field and to get the flux calibration. A pointing model was established in the first days of the runs. The average relative pointing accuracy is 3 arcsec. The beam at 350 microns has been estimated to be 8.5 arcsec, which is in good agreement with the beam of the 12 m APEX dish. Several observing modes have been tested, like On-The-Fly for beam-maps or large maps, spirals or raster of spirals for compact sources. With this preliminary version of ArTeMiS, we concluded that the mapping speed is already more than 5 times better than the previous 350 microns instrument at APEX. The median NEFD at 350 microns is 600 mJy.s1/2, with best values at 300 mJy.s1/2. The complete instrument with 5760 pixels and optimized settings will be installed during the first half of 2015.Comment: 11 pages, 11 figures. Presented at SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, June 24, 2014. To be published in Proceedings of SPIE Volume 915

A versatile silicon-silicon nitride photonics platform for enhanced functionalities and applications

Silicon photonics is one of the most prominent technology platforms for integrated photonics and can support a wide variety of applications. As we move towards a mature industrial core technology, we present the integration of silicon nitride (SiN) material to extend the capabilities of our silicon photonics platform. Depending on the application being targeted, we have developed several integration strategies for the incorporation of SiN. We present these processes, as well as key components for dedicated applications. In particular, we present the use of SiN for athermal multiplexing in optical transceivers for datacom applications, the nonlinear generation of frequency combs in SiN micro-resonators for ultra-high data rate transmission, spectroscopy or metrology applications and the use of SiN to realize optical phased arrays in the 800–1000 nm wavelength range for Light Detection And Ranging (LIDAR) applications. These functionalities are demonstrated using a 200 mm complementary metal-oxide-semiconductor (CMOS)-compatible pilot line, showing the versatility and scalability of the Si-SiN platform

Courants permanents dans des anneaux mésoscopiques connectés

Persistent currents in a ring threated by a magnetic flux is one of the most basic properties of mesoscopic physics. In the presence of a magnetic flux, a mesoscopic normal metal ring carries an equilibrium non-dissipative persistent current. Key experiements have confirmed the existence of persistent currents in isolated rings, although many experimental facts are still not well understood. In this context, an important question is to know if persistent currents can survive in a geometry of connected rings, the total size of the system being much longer than Lphi.We have fabricated a sample with four and sixteen connected rings, etched in a gallium arsenide heterostructure. The magnetization due to persistent currents is detected with aluminium µ-squids, deposited on the top of the rings in order to have the best coupling. Moreover, metallic gates were included in order to have an accurate measurement of the noise level, and a calibration loop allows to have absolute magnetization measurements of the persistent currents in one ring.Our experiment shows that the persistent currents still exist in a geometry where the rings are connected, the total length of the system being much longer than Lphi. Moreover, we have shown that the amplitude of the persistent currents is not significantly modified when connecting or isolating the rings. OUr results show that the persistent currents are not a specific property of isolated system smaller than Lphi : it is a robust effect that may be observed even in macroscopic samples.Le phénomène des courants permanents dans un anneau traversé par un flux magnétique est un des problèmes les plus fondamentaux de la physique mésoscopique. A l'équilibre thermodynamique, en présence d'un flux magnétique, un anneau conducteur est parcouru par un courant non dissipatif, et ce, bien qu'il ne soit pas supraconducteur. L'existence de ces courants permanents dans des systèmes isolés a pu être établie avec certitude par quelques expériences historiques, même si de nombreux faits expérimentaux restent encore inexpliqués. Il apparaît alors qu'une question primordiale est de savoir si les courants permanents peuvent survivre dans une géométrie d'anneaux connectés, et ce, même si la taille totale du système devient très grande devant Lphi.Nous avons donc réalisé un échantillon comportant quatre ou seize anneaux connectés entre eux, et gravés dans une hétérojonction d'arséniure de gallium. La détection de l'aimantation due aux courants permanents est réalisée par un µ-squid en aluminium, déposé directement sur les anneaux pour un couplage optimal. De plus, un système de grilles métalliques nous permet d'obtenir une mesure précise du niveau de bruit, et une boucle d'étalonnage permet de relier simplement le signal d'aimantation à l'amplitude du courant permanent circulant dans les anneaux.Nous avons ainsi pu montrer deux faits expérimentaux nouveaux : les courants permanents existent toujours dans une géométrie où les anneaux sont connectés, et ce même si la longueur totale de la chaîne d'anneaux est très grande devant Lphi. Par ailleurs, nous avons établi que l'amplitude des courants permanents n'est pas sensiblement modifié que les anneaux soient connectés ou non. Ces résultats montrent que les courants permanents ne sont pas une propriété spécifique aux systèmes isolés et plus petits que Lphi ; il s'agit donc d'un effet quantique robuste, que l'on peut penser observer dans des sytèmes macroscopiques

Anomalous temperature dependence of the dephasing time in mesoscopic Kondo wires

4 pages, 5 figures.We present measurements of the magnetoconductance of long and narrow quasi one-dimensional gold wires containing magnetic iron impurities in a temperature range extending from $15$mK to $4.2$K. The dephasing rate extracted from the weak antilocalisation shows a pronounced plateau in a temperature region of $300$mK - $800$mK, associated with the phase breaking due to the Kondo effect. Below the Kondo temperature the dephasing rate decreases linearly with temperature, in contradiction with standard Fermi-liquid theory. Our data suggest that the formation of a spin glass due to the interactions between the magnetic moments are responsible for the observed anomalous temperature dependence

SIN integrated optical phased arrays for two-dimensional beam steering at a single near-infrared wavelength

International audienceIn this work, we present two-dimensional beam steering in the near-infrared using a SiN integrated circuit, containing optical phased arrays. Beam steering was achieved over a range of 17.6 degrees x 3 degrees, at a fixed wavelength of 905 nm. The first dimension was steered via phase differences between the optical phased array channels. The second dimension was accessed by actively switching between various optical phased array sub-devices containing output diffraction gratings with different periods. The characterisation was performed on a wafer-level test station

Design of a small pitch (7.5µm) MWIR HgCdTe array operating at high temperature (130K) with high imaging performances

Event: SPIE Defense + Commercial Sensing, 2022, Orlando, Florida, United StatesInternational audienceSWAPc (Size, Weight And Power-cost) is a strong trend in IR imaging systems. It requires focal planearrays with smaller pixels, operating at high temperatures. For MW systems, the full spectral band (upto 5µm) shows a strong advantage over the blue band (4.1µm) as it maximizes the number of incomingphotons from a room temperature scene. Few years ago, LETI and Lynred have been developing7.5µm pitch MCT arrays in MW full band. The first version of this technology was based on n/p diodesoperating at 110K maximum temperature. Switching to p/n using extrinsic doping allows today animportant gain in dark current, enabling operating temperature up to 130K or even higher. This paperwill describe our latest results in the design and fabrication of such HOT small pitch arrays, startingwith test chip arrays, followed by the full the characterization of 1280x1024 7.5µm pitch arrays. Firstorder figure of merit (dark current, QE…) are of course considered, but second order figure of meritwill also be discussed such as noise tails

Peripheral devices for the right light

The closer the relation between the user and his requirements in terms of light provided in space and time, the better the comfort. These demands were fulfilled by advanced sensors and EnLight’s distributed rules based intelligence concept. Various physical parameters are important and need to be measured to allow proper decision-making such as occupancy, position of people in a room, level of outside lighting and temperature. Within the scope of the EnLight project, Fraunhofer IIS/EAS developed a low-power presence detector, based on an image-sensor system-on-chip (SoC). In contrast to traditional solutions, such as passive infrared (PIR) sensors, this system processes the image in the visible and near infrared spectrum, and derives texture features from visual information. A self-learning multi-modal algorithm analyzes the scene at a frame rate of up to ten frames per second. People can be localized within the field of view and distinguished from technical objects according to the active area and typical motion. In contrast to gray-scale algorithms the chosen approach is highly tolerant to brightness variations occurring due to incoming sunlight or switched luminaires

Reflection 2D real time THz camera to image and identify sugar pellets

International audienc