Zobrazení zdroje stránky Brennangustafsson7070

We demonstrate new axisymmetric inverse-design techniques that can solve problems radically different from traditional lenses, including reconfigurable lenses (that shift a multi-frequency focal spot in response to refractive-index changes) and widely separated multi-wavelength lenses (λ = 1 µm and 10 µm). We also present experimental validation for an axisymmetric inverse-designed monochrome lens in the near-infrared fabricated via two-photon polymerization. Axisymmetry allows fullwave Maxwell solvers to be scaled up to structures hundreds or even thousands of wavelengths in diameter before requiring domain-decomposition approximations, while multilayer topology optimization with ∼105 degrees of freedom can tackle challenging design problems even when restricted to axisymmetric structures.We report a highly sensitive twist sensor based on a Sagnac interferometer constructed with a new type of optical fiber which contains an elliptical core and two large semicircular-holes, where the slow axis of the core orthogonal to the air-holes has a large sensitivity towards twist-induced birefringent changes. The novel fiber structure results in a highest twist sensitivity of 5.01 nm/° at a chosen dip over the range from 370°-400°. The resonance dips in the interference pattern respond with different rates in the wavelength shifts in the presence of physical parameters permitting to experimentally distinguish directional torsion, axial strain and temperature.We show theoretically and numerically that when strongly focusing a circularly polarized optical vortex, the longitudinal component of its spin angular momentum undergoes inversion. A left-handed circularly polarized input beam is found to convert in the focus and near the optical axis to a right-handed circularly polarized beam. Thanks to this effect taking place near the strong focus, where a reverse energy flow is known to occur, the spin angular momentum inversion discovered can be utilized to detect a reverse energy flow.It is prohibitively expensive to deposit customized dielectric coatings on individual optics. One solution is to batch-coat many optics with extra dielectric layers, then remove layers from individual optics as needed. Here we present a low-cost, single-step, monitored wet etch technique for reliably removing individual SiO2 and Ta2O5 dielectric layers, in this case from a high-reflectivity fiber mirror. By immersing in acid and monitoring off-band reflected light, we show it is straightforward to iteratively (or continuously) remove six bilayers. At each stage, we characterize the coating performance with a Fabry-Pérot cavity, observing the expected stepwise decrease in finesse from 92,000 ± 3,000 to 3, 950 ± 50, finding no evidence of added optical losses. The etch also removes the fiber's sidewall coating after a single bilayer, and, after six bilayers, confines the remaining coating to a 60-µm-diameter pedestal at the center of the fiber tip. Vapor etching above the solution produces a tapered "pool cue" cladding profile, reducing the fiber diameter (nominally 125 µm) to 95 µm at an angle of ∼0.3° near the tip. Finally, we note that the data generated by this technique provides a sensitive estimate of the layers' optical depths. This technique could be readily adapted to free-space optics and other coatings.We proposed a differential fiber-optic SPR remote sensor with ultra-high sensitivity in telecom band. The working band of the sensor is designed as the C-band which is the low loss band of optical fiber communication aiming to improve the sensitivity and enable the capability of remote monitoring. The sensor head is a BK7 prism coated with Au/TiO2 films, enabling two channels for differential intensity interrogation. The intensities of the reflected lights through the channels vary oppositely within the measurement range of refractive index. Due to the sharp dip of angular resonant response in the C-band, the differential signal produces a steep slope as the refractive index of the sample varies, thus higher sensitivity is expected in a narrow measurement range. According to the results, the sensitivity is as high as 456 V/RIUs within the narrow measurement range of 1.3×10-2 RIUs and the resolution reaches to 6×10-6 RIUs. The measurement range can be tuned conveniently by adjusting the thickness of TiO2 film and can be expanded by increasing the number of sensing channels, which provides great convenience for the application of biosensor requiring high sensitivity.Additional laser energy absorption of optical elements limits the further development of high-energy laser systems. In engineering, inexpensive and precise absorption test technology is essential. We attempt to predict energy absorption via surface spatial error value based on the roughness-induced absorption (RIA) theory. However, the absorption coefficients cannot match roughness values measured with an atomic force microscope or white light interferometer. We find three influencing factors and optimize the definition of RIA to spatial error-induced absorption (SEIA). SEIA is proportional to δ2 of a mid- and high-spatial frequency error in a certain frequency range. This range depends on laser diameter, wavelength, and coating. Excluding the absorption induced by fabrication defects, the total absorption can be classified into SEIA and background absorption (BGA). BGA is decided by material and process technology, which can be obtained by calculations. The sum of SEIA and BGA is predictable because both can be estimated. The substrate absorption of high-energy optics can be semi-quantificationally predicted. SEIA provides a new angle to research element-absorbed laser energy for high-power laser technologies.The authors wish to make the following corrections to this paper [...].The author wishes to make the following correction to this paper [...].Viral infections are known to lead to serious respiratory complications in cystic fibrosis (CF) patients. Hypothesizing that CF patients were a population at high risk for severe respiratory complications from SARS-CoV-2 infection, we conducted a national study to describe the clinical expression of COVID-19 in French CF patients. This prospective observational study involves all 47 French CF centers caring for approximately 7500 CF patients. Between March 1st and June 30th 2020, 31 patients were diagnosed with COVID-19 19 had positive SARS-CoV-2 RT-PCR in nasopharyngeal swabs; 1 had negative RT-PCR but typical COVID-19 signs on a CT scan; and 11 had positive SARS-CoV-2 serology. Fifteen were males, median (range) age was 31 (9-60) years, and 12 patients were living with a lung transplant. The majority of the patients had CF-related diabetes (n = 19, 61.3%), and a mild lung disease (n = 19, 65%, with percent-predicted forced expiratory volume in 1 s (ppFEV1) &gt; 70). Three (10%) patients remained asymptomatic. [https://www.selleckchem.com/products/pifithrin-alpha.html Pifithrin-α in vivo] For the 28 (90%) patients who displayed symptoms, most common symptoms at admission were fever (n = 22, 78.