Parity–time reversal symmetry (PT-symmetry) in non-Hermitian systems realizes spontaneous symmetry breaking, thereby leading to counterintuitive phenomena. A coupled system with antisymmetric gain/loss profiles is required to introduce PT-symmetry into photonics. Remarkably, exciton-polaritons (the hybrid nature of excitons and photons) are directly interactive via excitonic components. Here we demonstrate that such direct coupling can remodel conventional photonic platforms of non-Hermitian systems into polaritonic platforms with a single component. We focused on the sixfold-symmetric microcavity to exploit degenerated photonic modes. By employing direct coupling with loss modulation, we observed room-temperature polaritonic PT symmetry with a phase transition from unbroken to broken, revealing the lowest threshold of polariton condensates in non-Hermitian degeneracies despite the increasing loss.

We present an all ZnO-based core-shell microrod, composed of a green light-emitting shell and a hexagonal microcavity core, obtained through the desulfurization treatment. The whispering gallery mode emission of the highly defective shell induced by the ZnO microcavity is realized. The resonant properties of the single core-shell microrod at different positions are investigated by the Cathodoluminescence measurement.

Solid-state HHG is anticipated to pave way for integrated XUV and attosecond light sources but typically relies on enormous light-matter interaction strengths which are difficult to attain in nano-optical systems with inherently small volumes. Here, we theoretically explore the synergies between electronic band structure and plasmonic resonances in the HHG yield of graphene and phosphorene and reveal the effects of size, edge termination, and doping in plasmon-assisted HHG. We apply a second-principles description based on Maximally Localized Wannier Functions which incorporate crucial finite-size and electronic bandstructure features in the nonlinear optical response of 2D materials patterned on mesoscopic length scales.

To develop laser spectroscopy in the vacuum ultraviolet (VUV) region, a simple wavelength conversion technique with wavelength- and polarization-controllability is needed. We demonstrated that third harmonic (TH) generation at arbitral wavelengths between 146 nm and 190 nm can be achieved by using a dielectric free-standing thin film (nanomembrane) as a nonlinear medium. Furthermore, by using a photonic crystal nanomembrane with square-lattice periodic nanoholes, we observed the circularly-polarized TH light at 157 nm. The observed intensity of VUV light can be applied to VUV spectroscopy, and the photonic crystal nanomembrane is a promising new tool for wavelength conversion to vacuum ultraviolet.

High-resolution periodic patterns such as gratings or two-dimensional arrays are required in many applications, especially in photonics devices such as near eye displays (AR/VR), DFB lasers or plasmonic or diffraction based biosensors. Displacement Talbot Lithography (DTL) is a new photolithography technique that enables patterning of large areas with high-resolution periodic structures. DTL offers resolution well below 100nm, which is sufficient even for the most demanding applications that require sub-wavelength resolution such as wire-grid polarizers or anti-reflection surfaces. The new imaging principle of DTL opens new possibilities in the field of photo lithography and its applications.

Ion chambers are used to measure the gas phase concentration of tritium, a radioactive hydrogen isotope. However, tritiated surface contamination regularly forms on ion chamber surfaces due to isotope exchange between tritium in the ambient with protium on the surface. This creates a large background signal which impedes low level measurement. Ion chambers may be periodically cleaned to reduce the background, but in tritium processing environments this increases risks of exposure to radiation and ion chamber breakage. In this report we describe the use of ultraviolet (UV) LED light illumination as means to decontaminate ion chambers in a safe, hand-free manner.

In this paper, far UV-C microplasma lamp with a flat form factor will be introduced for its performance to prevent airborne transmission of the virus by continuous viral density reduction in an indoor space. Unlike conventional UVC germicidal lights, which is harmful if it strikes the human body, far UVC (222 nm) photons from KrCl* excimer has recently been demonstrated to be harmless to human skin or eyes during direct exposure at occupied spaces. Details concerning the lamp characteristics, effectiveness and safety studies, current applications, and prospects of the future use of the Far-UVC lamps will be discussed.