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A robust, easy-to-fabricate, and sensitive liquid refractometric sensor utilizing optical fiber resonators (OFRs) obtained by simple stripping and cleaning of conventional optical fibers is presented. The sensing scheme is based on recording the spectral changes of the whispering gallery modes (WGMs) observed in the transmission spectrum of an OFR excited with a tunable laser coupled to the OFR through an independent tapered optical fiber. The demonstrated sensor device is tested and fully characterized with water solutions of ethanol and ethylene glycol (EG). Good agreements are obtained with theoretical predictions for both ethanol and EG cases when TE and TM polarized WGMs are considered. The limit of detection of the demonstrated sensor is determined to be between 2.7 and 4.7 × 10 −5 refractive index unit (RIU) comparable to the state-of-the-art when precise temperature control of the sample chamber is missing.

Photo-thermo-refractive glass is a promising material because it combines the properties of several monofunctional materials in it. These glasses can be doped with rare earth ions and can then be used for many practical applications. But the major problem is the low absorption coefficient. So, a lot of research has been done to grow silver nanoclusters and nanoparticles for improving the spectroscopic properties of rare-earth ions. In this study we present a way to transfer energy from silver clusters to Eu3+ ions in the PTR glass. These results can be used for developing warm white LEDs and down converters for solar cells.

Optical fiber resonator (OFR) sensor is presented for bulk liquid refractive index (RI) sensing. The sensing mechanism relies on the spectral shifts of whispering gallery modes (WGMs) of OFRs which are excited using a tapered fiber. OFR liquid RI sensor is fully characterized using water solutions of ethanol and ethylene glycol (EG). A good agreement is achieved between the analytical calculations and experimental results for both TE and TM polarizations. The detection limit for bulk RI is calculated to be between 2.7 - 4.7 x 10(-5) refractive index unit (RIU). The OFR sensor provides a robust, easy-to-fabricate and sensitive liquid refractive index sensor which can be employed in lab-on-a-chip applications., NA

In this work, superconducting pellets without lead (Pb) as well as with different concentrations of lead are prepared by solid state reaction. The prepared samples are then characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). The superconducting properties are examined using electrical resistivity and transport critical current density J c . Our results show that the sample prepared with calcination of 48 hours with intermediate grinding has the ideal value of the superconducting transition temperature T c and transport critical current density J c .