Highly fluorescent perovskite materials have attracted considerable interest for fundamental research and potential applications. In this work, we demonstrate the recoverable PL quenching of methylammonium lead halides (MAPbX₃, where X is Cl, Br or I) upon exposure to gaseous ammonia that enables the use of hybrid perovskites in gas-sensing applications. XRD analysis confirmed that the MA cations in the perovskite material were replaced by NH₃ to form NH₄PbX₃·MA, thereby resulting in distinct changes in the crystalline structure and, consequently, PL quenching. However, as a weak coordination complex, NH₄PbX₃·MA can be easily thermally decomposed to recover the starting product MAPbX₃ with the release of ammonia. An in-depth understanding of the reversible chemical and structural changes of the perovskites by exposing them to polar molecules such as ammonia can advance the development of hybrid perovskite sensors and provides insights into the mechanisms of how perovskites coordinate with polar molecules.

Glass microstructured optical fibers have been rendered biologically active for the first time via the immobilization of antibodies within the holes in the fiber cross-section. This has been done by introducing coating layers to the internal surfaces of soft glass fibers. The detection of proteins that bind to these antibodies has been demonstrated experimentally within this system via the use of fluorescence labeling. The approach combines the sensitivity resulting from the long interaction lengths of filled fibers with the selectivity provided by the use of antibodies.

We report fabrication of the lead silicate microstructured fibers (MOFs) with core holes as small as 20nm, the smallest holes fabricated within the core of an optical fiber to date. We show that light confinement and average mode intensity within such holes are strongly dependent on the hole size. Light confinement within 80nm and 250nm core hole within the fabricated MOFs has been experimentally characterized using Scanning Near-field Optical Microscopy (SNOM).

High index Er-Yb codoped tellurite spheres with diameter of 9 μm and good sphericity were fabricated using a CO₂ laser. Upconversion modulated whispering gallery modes with a quality factor of 45,000 were observed in the sphere dipped in methanol. Refractometric sensing with detection sensitivity of 7.7 nm/RIU was demonstrated using a 9 μm diameter sphere. Such high index spheres have the potential to be used for nanoparticle sensing and mid-IR frequency conversion.

Agarwood is a precious aromatic plant which has good pharmacological effects such as antidepressant and sedation. It also has good ornamental and collection value. However, due to it is long and complex production process, the output of agarwood essential oils (AEOs) is scarce, so the price is expensive, the quality is uneven, and the adulteration events is endless. From the commercial and pharmaceutical point of view, the authenticity and quality of the commercial products labeled as AEOs is very important. This paper tested the applicability of Raman spectroscopy combined with chemometrics in classification and authenticity identification of AEOs. In this study, Raman spectroscopy and principal component analysis (PCA) combined with partial least square discriminant analysis (PLS-DA) were used to comprehensively evaluate AEOs from different geographical origins and/or extracted by different methods which showed different characteristic bands. The characteristic component of AEOs, chromone derivatives, and two commonly used adulterants were also detected. These characteristic bands provide spectrum information of AEO samples and reference materials, which can be used as Raman spectral markers for the qualitative identification of AEOs. This study can provide a novel, fast and convenient method for identification of AEOs.

Plasmonic devices using periodic metallic nanostructures have recently gained tremendous interest for color filters, sensing, surface enhanced spectroscopy, and enhanced photoluminescence, etc. However, the performance of such plasmonic devices is severely hampered by the solid substrates supporting the metallic nanostructures. Here, a strategy for freestanding metallic nanomembranes is introduced by taking advantages of hollow substrate structures. Large-area and highly uniform gold nanomembranes with nanohole array are fabricated via a flexible and simple replication-releasing method. The hollow structures include a hollow core fiber with 30 μm core diameter and two ferrules with their hole diameter as 125 and 500 μm, respectively. As a proof-of-concept demonstration, 2 times higher sensitivity of the bulk refractive index is obtained with this platform compared to that of a counterpart on a solid silica substrate. Such a portable and compact configuration provides unique opportunities to explore the intrinsic properties of the metal nanomembranes and paves a new way to fabricate high-performance plasmonic devices for biomolecule sensing and color filter.