Recent advances in miniaturized optical gyroscopes

Low-cost chip-scale optoelectronic gyroscopes having a resolution ≤ 10 °/h and a good reliability also in harsh environments could have a strong impact on the medium/high performance gyro market, which is currently dominated by well-established bulk optical angular velocity sensors. The R&D activity aiming at the demonstration of those miniaturized sensors is crucial for aerospace/defense industry, and thus it is attracting an increasing research effort and notably funds.  In this paper the recent technological advances on the compact optoelectronic gyroscopes with low weight and high energy saving are reviewed. Attention is paid to both the so-called gyroscope-on-a-chip, which is a novel sensor, at the infantile stage, whose optical components are monolithically integrated on a single indium phosphide chip, and to a new ultra-high Q ring resonator for gyro applications with a configuration including a 1D photonic crystal in the resonant path. The emerging field of the gyros based on passive ring cavities, which have already shown performance comparable with that of optical fiber gyros, is also discussed

Double electromagnetically induced transparency resonance in slotted metasurfaces supporting bound states in the continuum

This work proposes and theoretically demonstrates a double electromagnetic induced transparency resonance generated by a novel dielectric metasurface consisting of a periodic array of square slots. The resonances stem from symmetry-protected bound states in the continuum whose quality factor tends to infinity when the structure is symmetric. The quasi-bound states in the continuum supported by the asymmetric metasurface can be exploited to obtain double high quality factor resonances in transmission (electromagnetic induced transparency like effect) that can be modulated with the external refractive index for sensing.This work was supported by Comunidad de Madrid and FEDER Program (S2018/NMT-4326), the Ministerio de Economía y Competitividad of Spain (TEC2016-77242-C3-1-R and TEC2016-76021-C2-2-R), the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (RTC2017-6321-1, PID2019-107270RB-C21 and PID2019-109072RB-C31)

Strongly resonant silicon slot metasurfaces with symmetry-protected bound states in the continuum

In this work, a novel all-dielectric metasurface made of arrayed circular slots etched in a silicon layer is proposed and theoretically investigated. The structure is designed to support both Mie-type multipolar resonances and symmetry-protected bound states in the continuum (BIC). Specifically, the metasurface consists of interrupted circular slots, following the paradigm of complementary split-ring resonators. This configuration allows both silicon-on-glass and free-standing metasurfaces and the arc length of the split-rings provides an extra tuning parameter. The nature of both BIC and non-BIC resonances supported by the metasurface is investigated by employing the Cartesian multipole decomposition technique. Thanks to the non-radiating nature of the quasi-BIC resonance, extremely high Q-factor responses are calculated, both by fitting the simulated transmittance spectra to an extended Fano model and by an eigenfrequency analysis. Furthermore, the effect of optical losses in silicon on quenching the achievable Q-factor values is discussed. The metasurface features a simple bulk geometry and sub-wavelength dimensions. This novel device, its high Q-factors, and strong energy confinement open new avenues of research on light-matter interactions in view of new applications in non-linear devices, biological sensors, and optical communications.Ministerio de Ciencia, Innovación y Universidades (PID2019-107270RB-C21, PID2019-109072RB-C31, RTC2017-6321-1); Comunidad de Madrid (S2018/NMT-4326); Ministerio de Economía y Competitividad (TEC2016-76021-C2-2-R, TEC2016-77242-C3-1-R)

Refractive index sensing by all-dielectric metasurfaces supporting quasi-bound states in the continuum

All-dielectric metasurfaces have attracted increasing attention due to their negligible losses and sharper resonances compared to their metallic counterparts. In this work, we numerically studied the optical performance of a novel alldielectric metasurface based on complementary split-ring resonators (CSRRs), in which ultrathin slots were periodically etched in a thin silicon layer. The proposed CSRR metasurface exhibits two multipolar resonances in the near-infrared (NIR) window. Moreover, a quasi-bound state in the continuum (quasi-BIC) with an ultra-high quality factor can be excited by breaking the symmetry of the structure. Taking advantage of the high-quality factor quasi-BIC mode and its sensitivity to the superstrate medium refractive index (S = [Di] res/[Dn]), we design an ultra-high figure of merit (FoM = S/FWHM) refractive index sensor for biomedical applications. By three-dimensional finite element method (3D-FEM), we evaluate the sensitivity of the sensing device to the variation of the superstrate refractive index in the range 1.31-1.33, which is typical for aqueous solutions. Our simulations reveal that a sensitivity of S ~ 155 nm RIU-1 and an extraordinary FoM ~ 387500 RIU-1 can be achieved using the ultra-narrow quasi-BIC resonance in the CSRR metasurface structure. The proposed approach opens new paths to develop flat biochemical sensors with high accuracy and real-time performance

Synergistic effect of static compliance and d-dimers to predict outcome of patients with covid-19-ards: A prospective multicenter study

The synergic combination of D-dimer (as proxy of thrombotic/vascular injury) and static compliance (as proxy of parenchymal injury) in predicting mortality in COVID-19-ARDS has not been systematically evaluated. The objective is to determine whether the combination of elevated D-dimer and low static compliance can predict mortality in patients with COVID-19-ARDS. A “training sample” (March–June 2020) and a “testing sample” (September 2020–January 2021) of adult patients invasively ventilated for COVID-19-ARDS were collected in nine hospitals. D-dimer and compliance in the first 24 h were recorded. Study outcome was all-cause mortality at 28-days. Cutoffs for D-dimer and compliance were identified by receiver operating characteristic curve analysis. Mutually exclusive groups were selected using classification tree analysis with chi-square automatic interaction detection. Time to death in the resulting groups was estimated with Cox regression adjusted for SOFA, sex, age, PaO2/FiO2 ratio, and sample (training/testing). “Training” and “testing” samples amounted to 347 and 296 patients, respectively. Three groups were identified: D-dimer ≤ 1880 ng/mL (LD); D-dimer > 1880 ng/mL and compliance > 41 mL/cmH2O (LD-HC); D-dimer > 1880 ng/mL and compliance ≤ 41 mL/cmH2O (HD-LC). 28-days mortality progressively increased in the three groups (from 24% to 35% and 57% (training) and from 27% to 39% and 60% (testing), respectively; p < 0.01). Adjusted mortality was significantly higher in HD-LC group compared with LD (HR = 0.479, p < 0.001) and HD-HC (HR = 0.542, p < 0.01); no difference was found between LD and HD-HC. In conclusion, combination of high D-dimer and low static compliance identifies a clinical phenotype with high mortality in COVID-19-ARDS

The STAR-RICH Detector

The STAR-RICH detector extends the particle idenfication capabilities of the STAR spectrometer for charged hadrons at mid-rapidity. It allows identification of pions and kaons up to ~3 GeV/c and protons up to ~5 GeV/c. The characteristics and performance of the device in the inaugural RHIC run are described

"Migrants, States, and EU Citizenship's Unfulfilled Promise"

A constant aim of EU citizenship, and indeed the entire project of European integration, has always been to lower barriers and create a common space. If the complete elimination of national borders remains elusive, their importance has been diminished in striking ways by the development of EU citizenship and the ban against nationality based discrimination. Yet the barriers to free movement have been lowered in differential ways. Most citizens of EU member states now enjoy residence, employment and other rights throughout Europe. The extension of some rights to some categories of citizens of some new member states is admittedly sometimes subject to transition periods, but these expire. By contrast, third country nationals -- individuals who do not hold citizenship of one of the member states, even though they may have resided for many years, or even been born in Europe -- remain largely excluded from the benefits of EU citizenship. Various initiatives over the years have opened up limited rights for third country nationals. But the difficulty of enacting these rights, and current moves to more restrictive immigration and naturalization policies, highlight the continuing exclusivity of EU citizenship: immigrants migrate to national polities, and they become European only by virtue of incorporation into national states. This means that EU citizenship's transformative potential remains unrealized.Glendon College (York University