In this paper, we report the exciton polaritons in both positive and negative detuning micro cavities based on InGaN multi-quantum wells (MQWs) and the first polariton lasing in InGaN/GaN MQWs at room temperature by utilizing a 4.5λ Fabry-Perot (F-P) cavity with double dielectric distributed Bragg reflectors (DBRs). Double thresholds corresponding respectively to polariton lasing and photonic lasing are observed along with half-width narrowing and peak blue-shifts. The threshold of polariton lasing is about half of the threshold of photonic lasing. Our results paved a substantial way for ultra-low threshold lasers and room temperature Bose-Einstein Condensate (BEC) in nitride semiconductors.

A transparent display simultaneously enables visualization of the images displayed on it as well as the view behind it, and therefore can be applied to, for instance, augmented reality (AR), virtual reality (VR), and head up display (HUD). Many solutions have been proposed for this purpose. Recently, the idea of frequency-selective scattering of red, green and blue light while transmitting visible light of other colours to achieve transparent projection display has been proposed, by taking advantage of metallic nanoparticle's localized surface plasmon resonance (LSPR). In this article, a review of the recent progress of frequency-selective scattering of red, green and blue light that are based on metallic nanoparticle's LSPR is presented. A discussion of method for choosing appropriate metal(s) is first given, followed by the definition of a figure of merit used to quantify the performance of a designed nanoparticle structure. Selective scattering of various nanostructures, including sphere-shaped nanoparticles, ellipsoidal nanoparticles, super-sphere core-shell nanoparticles, metallic nanocubes, and metallic nanoparticles combined with gain materials, are discussed in detail. Each nanostructure has its own advantages and disadvantages, but the combination of the metallic nanoparticle with gain materials is a more promising way since it has the potential to generate ultra-sharp scattering peaks (i.e., high frequency-selectivity).