Cesium lead halide perovskite nanowires have emerged as promising low-dimensional semiconductor structures for integrated photonic applications. Understanding light-matter interactions in a nanowire cavity is of both fundamental and practical interest in designing low-power-consumption nanoscale light sources. In this work, high-quality in-plane aligned halide perovskite CsPbX (X = Cl, Br, I) nanowires are synthesized by a vapor growth method on an annealed M-plane sapphire substrate. Large-area nanowire laser arrays have been achieved based on the as-grown aligned CsPbX nanowires at room temperature with quite low pumping thresholds, very high quality factors, and a high degree of linear polarization. More importantly, it is found that exciton-polaritons are formed in the nanowires under the excitation of a pulsed laser, indicating a strong exciton-photon coupling in the optical microcavities made of cesium lead halide perovskites. The coupling strength in these CsPbX nanowires is dependent on the atomic composition, where the obtained room-temperature Rabi splitting energy is ∼210 ± 13, 146 ± 9, and 103 ± 5 meV for the CsPbCl, CsPbBr, and CsPbI nanowires, respectively. This work provides fundamental insights for the practical applications of all-inorganic perovskite CsPbX nanowires in designing light-emitting devices and integrated nanophotonic systems.

Vanadium dioxide/titanium nitride (VO /TiN) smart coatings are prepared by hybridizing thermochromic VO with plasmonic TiN nanoparticles. The VO /TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO /TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO /TiN promising as smart energy-saving windows.

Vertical gold-nanogaps are created on microtubular cavities to explore the coupling between resonant light supported by the microcavities and surface plasmons localized at the nanogaps. Selective coupling of optical axial modes and localized surface plasmons critically depends on the exact location of the gold-nanogap on the microcavities which is conveniently achieved by rolling-up specially designed thin dielectric films into three dimensional microtube ring resonators. The coupling phenomenon is explained by a modified quasi-potential model based on perturbation theory. Our work reveals the coupling of surface plasmon resonances localized at the nanoscale to optical resonances confined in microtubular cavities at the microscale, implying a promising strategy for the investigation of light-matter interactions.

We report on design and fabrication of patterned plasmonic dimer arrays by using an ultrathin anodic aluminum oxide (AAO) membrane as a shadow mask. This strategy allows for controllable fabrication of plasmonic dimers where the location, size, and orientation of each particle in the dimer pairs can be independently tuned. Particularly, plasmonic dimers with ultrasmall nanogaps down to the sub-10 nm scale as well as a large dimer density up to 1.0 × 10 cm are fabricated over a centimeter-sized area. The plasmonic dimers exhibit significant surface-enhanced Raman scattering (SERS) enhancement with a polarization-dependent behavior, which is well interpreted by finite-difference time-domain (FDTD) simulations. Our results reveal a facile approach for controllable fabrication of large-area dimer arrays, which is of fundamental interest for plasmon-based applications in surface-enhanced spectroscopy, biochemical sensing, and optoelectronics.

Semiconducting surface‐enhanced Raman scattering (SERS) materials have attracted tremendous attention for their good signal uniformity, chemical stability, and biocompatibility. Here, a new concept to design high sensitivity semiconducting SERS substrates through integration of both amorphous and nonstoichiometric features of WO3−x thin films is presented. The integration of these two features provides narrower bandgap, additional defect levels within the bandgap, stronger exciton resonance, and higher electronic density of states near the Fermi level. These characteristics lead to a synergy to promote the photoinduced charge transfer resonance between analytes and substrate by offering efficient routes of charge escaping and transferring as well as strong vibronic coupling, thus realizing high SERS activity on amorphous nonstoichiometric WO3−x films.