Rapid and sensitive standoff measurement techniques are needed for detection of trace chemicals in outdoor plume releases, for example from industrial emissions, unintended chemical leaks or spills, burning of biomass materials, or chemical warfare attacks. Here, we present results from 235 m standoff detection of transient plumes for 5 gas-phase chemicals Freon 152a (1,1-difluoroethane), Freon 134a (1,1,1,2-tetrafluoroethane), methanol (CH3OH), nitrous oxide (N2O), and ammonia (NH3). A swept-wavelength external cavity quantum cascade laser (ECQCL) measures infrared absorption spectra over the range 955-1195 cm-1 (8.37- 10.47 µm), from which chemical concentrations are determined via spectral fits. The fast 400 Hz scan rate of the swept-ECQCL enables measurement above the turbulence time-scales, reducing noise and allowing plume fluctuations to be measured. For high-speed plume detection, noise-equivalent column densities of 1-2 ppm*m are demonstrated with 2.5 ms time resolution, improving to 100-400 ppb*m with 100 ms averaging.A one-micron pixel pitch is believed to be required for spatial light modulators (SLMs) to realize holographic displays possessing a wide viewing zone. This study proposes the use of a microelectromechanical systems (MEMS) SLM for not only displaying holographic patterns but also scanning laser beam. During the rotation of MEMS mirrors in the MEMS SLM, the timing of laser pulses illuminating the MEMS SLM is controlled to change the reflection direction of light modulated by the MEMS SLM in order to enlarge the viewing zone. In this technique, the width of the viewing zone depends on the rotation angle of MEMS mirrors, and not on the pitch of pixels (MEMS mirrors). We experimentally demonstrated the enlargement of the viewing zone angle to ∼40° using the MEMS SLM with a pixel pitch of 13.68 µm.Light waves propagating through complex biological tissues are spatially spread by multiple light scattering, and this spread limits the working depth in optical bioimaging, phototherapy, and optogenetics. Here, we propose the iterative phase conjugation of time-gated backscattered waves for enhancing the light energy delivered to a target object embedded in a scattering medium. We demonstrate the enhancement of light energy delivered to a target object hidden behind a 200-µm-thick mouse skull by more than ten times in comparison with the initial random input. The maximum enhancement was reached in only 10 iterations, more than a hundred times smaller than existing methods based on either a time-gated reflection matrix or iterative feedback optimization of the time-gated reflection intensity. Consequently, the proposed method is less sensitive to sample perturbations. Furthermore, the number of images required for optimization remained almost unchanged with an increase in the illumination area, unlike existing methods, where the convergence time scales with the illumination area. The proposed method provides high operation speed over a wide illumination area, which can facilitate the use of wavefront shaping in practical applications.High speed visible light communication (VLC) is a technology with great potential for future mobile and wireless communication. Here, we report and demonstrate a 2.705 Gbit/s white-light VLC and illumination system supporting indoor transmission distance of 1.5 m, corresponding a illumination of 545 lux. We also study the performance tolerance offset ranges in both x- and y-directions.Undersampling in Fourier single pixel imaging (FSI) is often employed to reduce imaging time for real-time applications. However, the undersampled reconstruction contains ringing artifacts (Gibbs phenomenon) that occur because the high-frequency target information is not recorded. Furthermore, by employing 3-step FSI strategy (reduced measurements with low noise suppression) with a low-grade sensor (i.e., photodiode), this ringing is coupled with noise to produce unwanted artifacts, lowering image quality. To improve the imaging quality of real-time FSI, a fast image reconstruction framework based on deep convolutional autoencoder network (DCAN) is proposed. The network through context learning over FSI artifacts is capable of deringing, denoising, and recovering details in 256 × 256 images. The promising experimental results show that the proposed deep-learning-based FSI outperforms conventional FSI in terms of image quality even at very low sampling rates (1-4%).Plasmonic metamaterials enable manipulation of light at subwavelength scales and exhibit unique optical functionalities. However, the realization of high-performance, large-range, and dynamically tunable optical absorbers based on plasmonic metamaterials remains challenging. Here, we propose and demonstrate a continuously tunable absorbers consisting of a zigzag array of bulk Dirac semimetals (BDS) meta-atoms and a metal reflector spaced by insulator layers. This structure exhibits a collective resonance formed by the electric dipole modes polarized along the long axis of each individual meta-atom, which allows us to precisely control this resonance frequency by fine-tuning the unit cell geometry and the Fermi energy levels of the BDS.  https://www.selleckchem.com/products/wnt-c59-c59.html  In addition, the related physical mechanism behind this complete absorption can explained by employing coupled-mode theory (CMT) and mode-expansion theory (MET). Our results may arouse the investigations of the tunable metamaterials device based on the BDS.With a three-dimensional classical ensemble method, we theoretically investigated frustrated double ionization (FDI) of atoms with different laser wavelengths. Our results show that FDI can be more efficiently generated with shorter wavelengths and lower laser intensities. With proper laser parameters more FDI events can be generated than normal double ionization events. The physical condition under which FDI events happen is identified and explained. The energy distribution of the FDI products - atomic ions in highly excited states - shows a sensitive wavelength dependency.In this study, the response of regenerated fiber Bragg gratings (RFGBs) to axial forces was investigated in a temperature range from room temperature to 900 °C. For the first time, the transition from pure elastic to viscoelastic behavior around 700 °C of a standard SMF28 optical fiber was measured with an inscribed RFBG. An elastic model with linear temperature dependencies of Young's modulus and Poisson's ratio was established, and showed good agreement with the measurements up to temperatures of ∼500 °C. In the temperature range up to 900 °C, the RFBG response could be well described with a simple, single-material approach and a Burgers model that consists of a Kelvin and a Maxwell part. Based on the elastic parameter of the Maxwell part, the temperature-dependent force sensitivity of the RFBG was determined, and it showed a linear decrease in the range from room temperature to ∼500 °C, constant values in the range between ∼500 °C and ∼600 °C, and a strong increase at higher temperatures. While fulfilling the condition to operate in the elastic domain of the silica fiber, the investigations demonstrate that RFBGs can be used as force sensors up to temperatures of ∼600 °C - the range in which temperature-dependent force sensitivities have to be considered.