Orbital angular momentum bistability in a microlaser

Light's orbital angular momentum (OAM) is an unbounded degree of freedom emerging in helical beams that appears very advantageous technologically. Using a chiral microlaser, i.e. an integrated device that allows generating an emission carrying a net OAM, we demonstrate a regime of bistability involving two modes presenting distinct OAM (L = 0 and L = 2). Furthermore, thanks to an engineered spin-orbit coupling of light in the device, these modes also exhibit distinct polarization patterns, i.e. cirular and azimuthal polarizations. Using a dynamical model of rate euqations, we show that this bistability arises from polarization-dependent saturation of the gain medium. Such a bistable regime appears very promising for implementing ultrafast optical switches based on the OAM of light. As well, it paves the way to the exploration of dynamical processes involving phase and polarization vortices

Quantifying n-Photon Indistinguishability with a Cyclic Integrated Interferometer

We report on a universal method to measure the genuine indistinguishability of n photons—a crucial parameter that determines the accuracy of optical quantum computing. Our approach relies on a low-depth cyclic multiport interferometer with N=2n modes, leading to a quantum interference fringe whose visibility is a direct measurement of the genuine n-photon indistinguishability. We experimentally demonstrate this technique for an eight-mode integrated interferometer fabricated using femtosecond laser micromachining and four photons from a quantum dot single-photon source. We measure a fourphoton indistinguishability up to 0.81 +- 0.03. This value decreases as we intentionally alter the photon pairwise indistinguishability. The low-depth and low-loss multiport interferometer design provides an original path to evaluate the genuine indistinguishability of resource states of increasing photon number

Biocapteurs à base de cristaux photoniques

National audienceno abstrac

Biocapteurs à base de cristaux photoniques

National audienceno abstrac

Engineering of slow Bloch modes for optical trapping

International audienceIn the present paper, we propose an approach based on slow Bloch mode microcavity that enables the optical trapping of small nanoparticles over a broad surface. A specific design based on a double-period photonic crystal is presented. It enables an easy coupling using a wide free-space Gaussian beam and the cavity Q factor can be tuned at will. Moreover, the microcavity mode is mainly localized within the photonic crystal holes, meaning that each hole of the microcavity behaves as efficient nanotweezers. Experimental studies have shown that 200 nm and 100 nm particles can be trapped within the microcavity, in a spatial region that corresponds to the size of one hole (200 nm wide). The experimental trap stiffness has been extracted. It shows that this approach is among the most performant ones if we take into account the size of the cavity

A multi-resistance wide-range calibration sample for conductive probe atomic force microscopy measurements

International audienceMeasuring resistances at the nanoscale has attracted recent attention for developing microelectronic components, memory devices, molecular electronics, and two-dimensional materials. Despite the decisive contribution of scanning probe microscopy in imaging resistance and current variations, measurements have remained restricted to qualitative comparisons. Reference resistance calibration samples are key to advancing the research-to-manufacturing process of nanoscale devices and materials through calibrated, reliable, and comparable measurements. No such calibration reference samples have been proposed so far. In this work, we demonstrate the development of a multi-resistance reference sample for calibrating resistance measurements in conductive probe atomic force microscopy (C-AFM) covering the range from 100 Ω to 100 GΩ. We present a comprehensive protocol for in situ calibration of the whole measurement circuit encompassing the tip, the current sensing device, and the system controller. Furthermore, we show that our developed resistance reference enables the calibration of C-AFM with a combined relative uncertainty (given at one standard deviation) lower than 2.5% over an extended range from 10 kΩ to 100 GΩ and lower than 1% for a reduced range from 1 MΩ to 50 GΩ. Our findings break through the long-standing bottleneck in C-AFM measurements, providing a universal means for adopting calibrated resistance measurements at the nanoscale in the industrial and academic research and development sectors

Optical trapping of 100nm nanoparticle on extended slow Bloch mode cavity

1-6 Février 2014International audienceno abstrac

Detachable three-layer Au absorber microfabrication for low-temperature detectors

Low temperature detectors (LTDs) used for decay energy spectrometry (DES) can provide accurate and reliable decay data thanks to their high-energy resolution and a near 100% detection efficiency for the radiations of interest. However, it is essential to consider the source quality to mitigate spectral distortion due to the self-absorption of particle energy in the source deposited.This work aimed to produce a replaceable 4π 3-layer gold absorber for DES in reusable metallic magnetic calorimeters, a class of LTDs. We present a novel 3-layer microfabrication process for a 1 mm diameter absorber with a total gold thickness ranging from 20 μm to 120 μm depending on the measured radionuclide (55Fe or 241Am). The absorber integrates a gold nanofoam in which the radionuclide is deposited by nanodrop deposition of a few tenths of μL of a radioactive solution. We fabricated a high quality gold nanofoam layer with controllable porosity through a dealloying process using wet etching and integrating it on a thick electrodeposited gold layer. The fine study of the nanofoam microfabrication is performed using high-resolution scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX)

Piégeage optique de billes de 100 nm sur une cavité photonique étendue

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