Estimation of the uncertainty for a phase noise optoelectronic metrology system

International audienceThe configuration of the phase noise measurement system operating in the X-band (8.2-12.4 GHz) using a photonic delay line as a frequency discriminator is presented in this paper. This system does not need any excellent frequency reference and works for any frequency in this band. Oscillator frequency fluctuation is converted into phase frequency fluctuation through the delay line. The measured phase noise includes the device under test noise and the instrument background. Then the use of a cross correlation decreases the cross spectrum terms of uncommon phase noise as √(1/m), where m is the average number. Using cross correlation on 500 averages, the noise floor of the instrument £(f) becomes, respectively, −150 and −170 dBc Hz−1 at 101 and 104 Hz from the 10 GHz carrier (−90 and −170 dBc Hz−1 including 2 km delay lines). We then focus on determining the uncertainty. There are two categories of uncertainty terms: 'type A', statistic contributions such as repeatability and experimental standard deviation; 'type B' due to various components and temperature control. The elementary term of uncertainty for repeatability is found to be equal to 0.68 dB. Other elementary terms still have lower contributions. This leads to a global uncertainty of 1.58 dB at 2σ

Shape-altering flexible plasmonics of in-situ deformable nanorings

Abstract Nanorings (NRs) with their intrinsic cavities have attracted interest as plasmonic nanoparticles for years, due to the uniform electric field enhancement inside the cavity, lower plasmon damping effects and comparatively high refractive index sensitivities. In the present work, we successfully fabricated a series of Au NR arrays on flexible polydimethylsiloxane substrates by taking advantage of state-of-the-art fabrication methods such as electron beam lithography and wet-etching transfer techniques. In-situ optical measurements on these flexible systems are enabled by implementing a homemade micro-stretcher inside an optical reflection spectroscopy setup. The corresponding dark-field spectra of thin-walled NR arrays exhibit a strong shift to longer wavelengths (i.e., ~ 2.85 nm per 1% strain) under polarization perpendicular to the traction, mainly resulting from the increasing shape deformation of the NRs under strain. Moreover, numerical simulations illustrate that the shifting plasmonic mode has a radially-symmetric charge distribution of the bonding mode and is rather sensitive to the tuning of the NRs’ shape as confirmed by a subsequent in-situ scanning electron microscope characterization. These results explore the possibilities of shape-altering flexible plasmonics for nanoparticles with a cavity and indicate potential applications for plasmonic colors and biochemical sensing in future work. Graphical Abstrac

Distinctive Effects of Surface Roughness and Ions Release on the Bacterial Adhesion and Inactivation of Textured Copper Oxide Surfaces

In this manuscript, we studied the effect of additive manufacturing pretreatment on bacterial adhesion and inactivation on copper-based interfaces. Sandblasting, mirror polishing and Surface Mechanical Attrition Treatment (SMAT) at high or low energies have been employed to modify the substrate’s (316L stainless steel) roughness. The pretreated substrates were coated with thin copper films using magnetron sputtering. The thin copper films’ composition and antibacterial activities were first optimized by being deposited on an Si wafer. We showed that the surface roughness profile influenced bacterial adhesion in the dark. Bacterial inactivation was monitored under indoor light. Stereomicroscopy imaging showed live/dead bacterial cells on the coated substrates. Scanning electron microscopy (SEM) showed homogeneous coating growths of copper with a columnar texture. The chemical composition of the deposited Cu thin films was carried out by Energy Dispersive X-ray Spectroscopy (EDX) and showed a uniform distribution of copper and oxygen, revealing the formation of copper oxides (CuxO). The oxygen content of the sputtered films varied from 7.8 to 25%, justifying the semi-conductor behavior of the thin films under indoor light. The crystallographic structure of the sputtered thin films was investigated using X-ray diffraction (XRD), showing the cubic Cu peaks and characteristic peaks of Cu2O. The Cu peaks at 2θ values of 43.28°, 50.40° and 74.81° were attributed to the (111), (200) and (220) planes, respectively. The use of genetically modified bacteria (without porins) allowed the rationalization of the predominant effect of the extracellular bacterial inactivation compared to that of intracellular bacterial inactivation through ion release and diffusion

Capteurs de pression plasmoniques pour aplications biomédicales

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Asymmetrical Dimer Photonic Crystals Enabling Outstanding Optical Sensing Performance

The exploration of the propensity of engineered materials to bring forward innovations predicated on their periodic nanostructured tailoring rather than the features of their individual compounds is a continuous pursuit that has propelled optical sensors to the forefront of ultra-sensitive bio-identification. Herein, a numerical analysis based on the Finite Element Method (FEM) was used to investigate and optimize the optical properties of a unidirectional asymmetric dimer photonic crystal (PhC). The proposed device has many advantages from a nanofabrication standpoint compared to conventional PhCs sensors, where integrating defects within the periodic array is imperative. The eigenvalue and transmission analysis performed indicate the presence of a protected, confined mode within the structure, resulting in a Fano-like response in the prohibited states. The optical sensor demonstrated a promising prospect for monitoring the DNA hybridization process, with a quality factor (QF) of roughly 1.53×105 and a detection limit (DL) of 4.4×10−5 RIU. Moreover, this approach is easily scalable in size while keeping the same attributes, which may potentially enable gaze monitoring

Analysis of the effect of surface mechanical attrition treatment on the mechanical properties of 17-4 PH stainless steel obtained by material extrusion

International audienceIn this study, the influence of the surface mechanical attrition treatment (SMAT) on a 17-4PH stainless steel made by material extrusion additive manufacturing is investigated under mechanical loading. The evolutions of the deformations at the local scale have been performed during in-situ tensile tests up to failure around 4kN. The strain maps are obtained with an original process based on the use of nanogauges displacement from the recorded of scanning electron microscope images. These maps allow to analyze the deformation mechanisms of as-fabricated and mechanically treated samples. The porosities evolutions at the surface are especially investigated for the two types of samples. The crack propagation in the as-fabricated samples is strongly influenced by porosities/defects related to the additive manufacturing process. Moreover, the SMATed samples present slip bands at the surface during the deformation. This deformation mechanism is similar to the one commonly observed in metallic materials obtained with traditional processes. Even if the application of SMAT does not show huge modifications of tensile properties with similar ultimate tensile strength around 650 MPa, it allows to improve the material surface quality by drastically reducing the surface roughness. SMAT treatment also allows a reduction of porosities in few microns from the sample surface. These improvements present a limited impact on tensile properties, but leads to its possible use for industrial applications when applied as an innovative post-treatment on metal part obtained by additive manufacturing

On phase noise in optoelectronic oscillator

International audienceThe optoelectronic microwave oscillator has large potential of application in telecommunication, space, radar systems due to its low phase noise level and high tunability. It usually consists of a pump laser, optical intensity modulator, optical delay line, photodetector, mode selection filter, and amplifier. We consider phase noise properties of different architectures of optoelectronic microwave oscillator. Influences of different components constituting the oscillator on its phase noise are shown. Results of phase noise estimation with using phase diffusion approach and results of measurements are presented

Asymmetrical Dimer Photonic Crystals Enabling Outstanding Optical Sensing Performance

The exploration of the propensity of engineered materials to bring forward innovations predicated on their periodic nanostructured tailoring rather than the features of their individual compounds is a continuous pursuit that has propelled optical sensors to the forefront of ultra-sensitive bio-identification. Herein, a numerical analysis based on the Finite Element Method (FEM) was used to investigate and optimize the optical properties of a unidirectional asymmetric dimer photonic crystal (PhC). The proposed device has many advantages from a nanofabrication standpoint compared to conventional PhCs sensors, where integrating defects within the periodic array is imperative. The eigenvalue and transmission analysis performed indicate the presence of a protected, confined mode within the structure, resulting in a Fano-like response in the prohibited states. The optical sensor demonstrated a promising prospect for monitoring the DNA hybridization process, with a quality factor (QF) of roughly 1.53×105 and a detection limit (DL) of 4.4×10−5 RIU. Moreover, this approach is easily scalable in size while keeping the same attributes, which may potentially enable gaze monitoring

Influence of mechanical attrition treatment on 17-4PH stainless steel: comparison at sub-micron scale between sent specimens produced by atomic diffusion additive manufacturing (ADAM) process

International audienceThis study focuses on the comparison between two types of single edge notched tensile (SENT) specimens made by Atomic Diffusion Additive Manufacturing (ADAM) process from Markforged Inc. The first type is submitted to Surface Mechanical Attrition Treatment (SMAT) and the second specimens are as fabricated. The deposition of gold nanoparticles (NP) at the surface, through Electron Beam Lithography (EBL), allows characterization at sub-micron scale. To observe the crack initiation and propagation, an in-situ tensile test if performed under scanning electron microscope (SEM) in order to track the NP displacements and the cracks evolution

Tunable sensitivity of a biosensor by strain modulation of a gap between gold dimers

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