Effect of wood on the sound of oboe as simulated by the chanter of a 16-inch French bagpipe

International audienceMany objective and subjective experiments on brass instruments, organs, flutes and clarinets have shown that the influence of material was weak. Yet, the influence of wood on the sound of oboes is still to be determined. In this study, short musical recordings of ten French 16″ bagpipes made of 5 different woods (African Ebony, Santos Rosewood, Boxwood, African Blackwood and Service Tree) were presented to subjects (specialist and naïve), who had to give their feedback on several criteria (global quality, warmth, aggressiveness, brightness, volume and attack precision). The choice of a bagpipe rather than a simple oboe enables to minimize the influence of the musician, as he is not directly in contact with the reed. An influence of the reed material was found, but no influence of the wood. In a second experiment, a discrimination task allowed to confirm that the differences between chanters were not principally due to the wood. Several physical parameters calculated from recorded signals could also not reveal any large differences between woods

Multiconfiguration GPR measurements for geometric fracture characterization in limestone cliffs (Alps)

Until now, geophysical methods have been rarely used to investigate vertical limestone cliffs, mainly due to the extreme conditions for data acquisition. Nevertheless, these techniques are the only available methods which could provide information on the internal state or a rock mass in terms of discontinuities, which play a major role in rock-fall hazards. In this case study, detailed GPR measurements were carried out on a test site with different acquisition configurations deployed on vertical cliff faces. Conventional 2D profiles, common midpoints (CMP) and transmission data were acquired to evaluate the potential of radar waves to improve the characterization of the geometry and properties of the main discontinuities (fractures) within the massif. The results show that the 3D geometry of fractures, which is a crucial parameter for stability assessment, can be retrieved by combining vertical and horizontal profiles performed along the cliff. CMP profiles acquired along the cliff allow a velocity profile to be obtained as a function of depth. Finally, transmission experiments, which generate complex radargrams, have provided valuable and quantitative information on the rock mass, through the modelling of the waves generated. On the other hand, a velocity tomography obtained from the first arrivals travelling through the rock mass from the transmitters to the receivers, shows an image of the investigated zone with a poor resolution

Deterministic radiative coupling between plasmonic nanoantennas and semiconducting nanowire quantum dots

International audienceWe report on the deterministic coupling between single semiconducting nanowire quantum dots emitting in the visible and plasmonic Au nanoantennas. Both systems are separately carefully characterized through microphotoluminescence and cathodoluminescence. A two-step realignment process using cathodoluminescence allows for electron beam lithography of Au antennas near individual nanowire quantum dots with a precision of 50 nm. A complete set of optical properties are measured before and after antenna fabrication. They evidence both an increase of the NW absorption, and an improvement of the quantum dot emission rate up to a factor two in presence of the antenna

Wave-mixing origin and optimization in single and compact aluminum nanoantennas

The outstanding optical properties for plasmon resonances in noble metal nanoparticles enable the observation of non-linear optical processes such as second-harmonic generation (SHG) at the nanoscale. Here, we investigate the SHG process in single rectangular aluminum nanoantennas and demonstrate that i) a doubly resonant regime can be achieved in very compact nanostructures, yielding a 7.5 enhancement compared to singly resonant structures and ii) the $\chi_{\perp\perp\perp}$ local surface and $\gamma_{bulk}$ nonlocal bulk contributions can be separated while imaging resonant nanostructures excited by a tightly focused beam, provided the $\chi_{\perp\parallel\parallel}$ local surface is assumed to be zero, as it is the case in all existing models for metals. Thanks to the quantitative agreement between experimental and simulated far-field SHG maps, taking into account the real experimental configuration (focusing and substrate), we identify the physical origin of the SHG in aluminum nanoantennas as arising mainly from $\chi_{\perp\perp\perp}$ local surface sources

Low power saturation of an ISB transition by a mid-IR quantum cascade laser

We demonstrate that absorption saturation of a mid-infrared intersubband transition can be engineered to occur at moderate light intensities of the order of 10-20 kW.$\text{cm}^{-2}$ and at room temperature. The structure consists of an array of metal-semiconductor-metal patches hosting a judiciously designed 253~nm thick GaAs/AlGaAs semiconductor heterostructure. At low incident intensity the structure operates in the strong light-matter coupling regime and exhibits two absorption peaks at wavelengths close to 8.9 $\mu$m. Saturation appears as a transition to the weak coupling regime - and therefore to a single-peaked absorption - when increasing the incident power. Comparison with a coupled mode theory model explains the data and permits to infer the relevant system parameters. When the pump laser is tuned at the cavity frequency, the reflectivity decreases with increasing incident power. When instead the laser is tuned at the polariton frequencies, the reflectivity non-linearly increases with increasing incident power. At those wavelengths the system therefore mimics the behavior of a saturable absorption mirror (SESAM) in the mid-IR range, a technology that is currently missing

Direct polariton-to-electron tunneling in quantum cascade detectors operating in the strong light-matter coupling regime

We demonstrate mid-infrared quantum cascade detectors (QCD) operating in the strong light-matter coupling regime. They operate around $\lambda = 10~\mu m$ with a minimum Rabi splitting of 9.3 meV. A simple model based on the usual description of transport in QCDs does not reproduce the polaritonic features in the photo-current spectra. On the contrary, a more refined approach, based on the semi-classical coupled modes theory, is capable to reproduce both optical and electrical spectra with excellent agreement. By correlating absorption/photo-response with the simulations, we demonstrate that - in this system - resonant tunneling from the polaritonic states is the main extraction mechanism. The dark intersubband states are not involved in the process, contrary to what happens in electrically injected polaritonic emitters

THz ultra-strong light-matter coupling up to 200K with continuously-graded parabolic quantum wells

Continuously graded parabolic quantum wells with excellent optical performances are used to overcome the low-frequency and thermal limitations of square quantum wells at terahertz frequencies. The formation of microcavity intersubband polaritons at frequencies as low as 1.8 THz is demonstrated, with a sustained ultra-strong coupling regime up to a temperature of 200K. It is additionally shown that the ultra-strong coupling regime is preserved when the active region is embedded in sub-wavelength resonators, with an estimated relative strength $\eta = \Omega_R / \omega_0 = 0.12$. This represents an important milestone for future studies of quantum vacuum radiation because such resonators can be optically modulated at ultrafast rates, possibly leading to the generation of non-classical light via the dynamic Casimir effect. Finally, with an effective volume of $2.10^{-6} \lambda_0^3$, it is estimated that fewer than 3000 electrons per resonator are ultra-strongly coupled to the quantized electromagnetic mode, proving it is also a promising approach to explore few-electron polaritonic systems operating at relatively high temperatures.Comment: 7 pages, 4 figure

Comparison of two enzymatic immunoassays, high resolution mass spectrometry method and radioimmunoassay for the quantification of human plasma histamine

International audienceHistamine (HA) is one of the main immediate mediators involved in allergic reactions. HA plasma concentration is well correlated with the severity of vascular and respiratory signs of anaphylaxis. Consequently, plasma quantification of HA is useful to comfort the diagnosis of anaphylaxis. Currently, radioimmunoassay (RIA) is the gold standard method to quantify HA due to its high sensitivity, but it is time consuming, implicates specific formations and cautions for technicians, and produces hazardous radioactive wastes. The aim of this study was to compare two enzymatic immunoassays (EIA) and one in-house liquid chromatography high-resolution mass spectrometry method (LC-HRMS) with the gold standard method for HA quantification in plasma samples of patients suspected of anaphylaxis reactions. Ninety-two plasma samples were tested with the 4 methods (RIA, 2 EIA and LC-HRMS) for HA quantification. Fifty-eight samples displayed HA concentrations above the positive cut-off of 10 nM evaluated by RIA, including 18 highly positive samples (>100 nM). Our results showed that Immunotech® EIA and LC-HRMS concentrations were highly correlated with RIA values, in particular for samples with a HA concentration around the positive cut-off. In our hands, plasma concentrations obtained with the Demeditec Diagnostics® EIA correlated less with results obtained by RIA, and an underestimation of plasma HA levels led to a lack of sensitivity. In conclusion, this study demonstrates that Immunotech® EIA and LC-HRMS method could be used instead of RIA to assess plasma HA in human diagnostic use

Detection of strong light-matter interaction in a single nano-cavity with a thermal transducer

Recently, the concept of strong light-matter coupling has been demonstrated in semiconductor structures, and it is poised to revolutionize the design and implementation of components, including solid state lasers and detectors. We demonstrate an original nanospectroscopy technique that permits to study the light-matter interaction in single subwavelength-sized nano-cavities where far-field spectroscopy is not possible using conventional techniques. We inserted a thin ($\approx$ 150 nm) polymer layer with negligible absorption in the mid-IR (5 $\mu$m < $\lambda$ < 12 $\mu$m) inside a metal-insulator-metal resonant cavity, where a photonic mode and the intersubband transition of a semiconductor quantum well are strongly coupled. The intersubband transition peaks at $\lambda$ = 8.3 $\mu$m, and the nano-cavity is overall 270 nm thick. Acting as a non-perturbative transducer, the polymer layer introduces only a limited alteration of the optical response while allowing to reveal the optical power absorbed inside the concealed cavity. Spectroscopy of the cavity losses is enabled by the polymer thermal expansion due to heat dissipation in the active part of the cavity, and performed using an atomic force microscope (AFM). This innovative approach allows the typical anticrossing characteristic of the polaritonic dispersion to be identified in the cavity loss spectra at the single nano-resonator level. Results also suggest that near-field coupling of the external drive field to the top metal patch mediated by a metal-coated AFM probe tip is possible, and it enables the near-field mapping of the cavity mode symmetry including in the presence of strong light-matter interaction