Photoluminescence enhancement with all-dielectric coherent metasurfaces

Mie resonances have recently attracted much attention in research on dielectric metasurfaces, owning to their enriched multipole resonances, negligible optical loss, and efficient light emitter integration. Although there is a rapid advancement in this field, some fundamental developments are still required to provide a simpler and more versatile paradigm for photoluminescence (PL) control. In this work, we proposed that an all-dielectric coherent metasurface can engineer the PL response by tuning the array size. Such PL manipulation is attributed to the collective Mie resonances that mediate the inter-unit interactions between unit elements and alter the PL intensity. Metasurfaces with different chip sizes are utilized to explore the array size effect on the collective Mie resonances, field enhancement, and Q-factor in TiO2 metasurfaces. Incorporating the all-dielectric coherent metasurface with fluorescent photon emitters, we performed the dependence of PL enhancement on array size, which achieves an enhancement factor of ∼10 at the central area of a 90 × 90 μm2 TiO2 metasurface array. These findings provide an additional degree of freedom to engineer the near-field confinement and enhancement, allowing one to manipulate incoherent photon emission and tune light–matter interaction at the nanoscale.

On the use of light sensors on CubeSat nanosatellites

The paper focuses on the usage of the TCS34725 light sensor in the motion control system of the SamSat-Science nanosatellite platform. The sensor is designed to determine the angle between the sensor normal and the direction to the light emitter center. We developed a technique for calibrating light sensors, carried out a series of experiments, verified the nominal characteristic of the light sensor, and found the dependency of mean squared deviation (MSD) of the sensor values on the angle of incidence of the light flux. Three layouts of light sensors on the lateral faces of the nanosatellite are considered: on a plane; on the faces of a quadrangular pyramid with an inclination angle of 45°; on the faces of a truncated quadrangular pyramid with an angle of inclination of 45°. We have chosen a circuit that provides measurements with minimum noise.

Photodegradation Properties of Earlywood and Latewood Spruce Timber Surfaces

Spruce (Picea abies Karst.) samples were irradiated using an ultraviolet light emitter mercury vapour lamp. The examined specimen surfaces contained earlywood or latewood to determine the photodegradation properties of these two tissue types. The generated chemical changes were monitored by diffuse reflectance Fourier transformed infrared spectroscopy. The difference spectrum method was used to present absorption changes. The earlywood suffered considerably greater degradation than the latewood during the UV irradiation. Most of the lignin molecules in the examined surface layer degraded during the first 11 days of UV irradiation for both earlywood and latewood. Results demonstrated that two types of unconjugated carbonyls absorbing at 1705 and 1764 cm–1 wavenumbers were created during the photodegradation. Time dependence of the absorption changes showed correlation between the guaiacyl lignin degradation and the generation of unconjugated carbonyl group absorbing at 1764 cm–1 wavenumber.

A color-tunable single molecule white light emitter with high luminescence efficiency and ultra-long room temperature phosphorescence

A simple emitter could simultaneously achieve bright white light emission with high quantum yield, ultra-long phosphorescence and excitation-dependent color-tunable emission.

Luminescence enhancement of lead halide perovskite light-emitting diodes with plasmonic metal nanostructures

Metal halide perovskites, as a newly emerging light-emitter, have been attracting considerable attention on luminescent materials and devices, due to their superior optoelectronic properties and potential practical applications. Recently, perovskite...