Crystalline zinc oxide (ZnO) thin films with highly preferential c-axis-oriented crystals were prepared using the reactive e-beam evaporation technique. Prior to deposition, ZnO targets were prepared from ZnO (99.999%) powder. Post-deposition thermal annealing was performed at various temperatures ranging from 200 to 700 °C for 2 h in air to investigate the effect of annealing on the structural and optical properties. Structural characterization including that of the crystal structure, crystal orientation, phase, stress, strain, grain size and surface morphology was carried out using x-ray diffraction (XRD) and atomic force microscopy (AFM). Optical characterization including transmission, absorption coefficient and band gap estimation was carried out using a spectrophotometer. The XRD results showed that the films were highly c-axis oriented before and after annealing. Crystallinity and grain size improved with annealing temperature. AFM results showed that the surface morphology improved with annealing temperature. Optical transmittance increases slightly and the band gap decreases with increasing annealing temperature. The effect of the stress formation during thin film deposition and its variation with post-deposition heat treatment and the effect of this stress on optical properties of the thin films were also studied. The residual compressive stress in as-deposited thin films relaxes with heat treatment and becomes tensile with further increase in annealing temperature. The optical band gap decreases with increasing grain size and decreases with increasing tensile stress.

We model the broadband enhancement of single-photon emission from color centres in silicon carbide nanocrystals coupled to a planar hyperbolic metamaterial (HMM) resonator.The design is based on positioning the single photon emitters within the HMM resonator, made of a dielectric index-matched with silicon-carbide material. The broadband response results from the successive resonance peaks of the lossy Fabry-Perot structure modes arising within the high-index HMM cavity. To capture this broadband enhancement in the single photon emitter's spontaneous emission, we placed a simple gold based cylindrical antenna on top of the HMM resonator. We analyzed the performance of this HMM coupled antenna structure in terms of the Purcell enhancement, quantum efficiency, collection efficiency and overall collected photon rate. For perpendicular dipole orientation relative to the interface, the HMM coupled antenna resonator leads to a significantly large spontaneous emission enhancement with Purcell factor of the order of 250 along with a very high average total collected photon rate (CPR) of about 30 over a broad emission spectrum (700 nm -1000 nm). The peak CPR increases to about 80 at 900 nm, corresponding to the emission of silicon-carbide quantum emitters. This is a state-of-the art improvement considering the previous computational designs have reported a maximum average CPR of 25 across the nitrogen-vacancy centre emission spectrum, 600 nm to 800 nm with the highest value being about 40 at 650 nm.

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A 26-year-old woman currently treated for systemic lupus erythematosus with steroid therapy presented with sudden onset of right hemiplegia. Computed tomography of the brain showed a large frontoparietal ring-enhanced lesion with perifocal edema. Stereotactic aspiration of the lesion revealed Cladosporium bantianum. The size of the abscess did not reduce in spite of optimum antifungal treatment. The abscess was subsequently excised through a frontoparietal craniotomy. At follow up after 24 months, there was no recurrence of the abscess. Cerebral Cladosporium bantianum infection is usually refractory to antifungal agents and the prognosis is very poor. This patient had the longest survival period in a case of Cladosporium brain abscess so far reported.

Recently, hyperbolic metamaterials (HMMs) have shown large emission-rate/Purcell enhancement for emitters coupled to them. However, due to the large momentum ( k ) mismatch between the high-k hyperbolic modes of HMMs and free-space modes, the far-field out-coupling of the emission is limited and requires an antenna. In this work, we present an in-depth theoretical study of the performance of some commonly known plasmonic antennas—cylindrical, cuboid, crossed, and bow-tie—when coupled to a HMM. Of all these antennas, the cylindrical antenna was observed to be the best for out-coupling to the high- k HMM modes with the Purcell factor and collection efficiencies reaching 1000 and 0.5, respectively. The hyperbolic HMM modes are observed to be efficiently coupled to the resonance modes of the cylindrical antenna, with the antenna modes getting effectively out-coupled into free space. These values are expected to result in two to three orders of fluorescence enhancement from a solid-state single photon source. For other antennas, the greater momentum mismatch between the hyperbolic HMM modes and the antenna modes resulted in relatively much weaker free-space out-coupling.