Colourful cloud: active photoluminescent smokescreen for multi-wavelength non-line-of-sight channel establishment and enhancement

Non-line-of-sight (NLOS) optical wireless scattering communication, a solution for broader optical communication scenarios, is vulnerable to challenges in complex medium environments, simultaneous multiple terminals, and interference with strong pertinence. Here, we have developed an innovative photoluminescent smokescreen based on inorganic perovskite with reconfigurable optical field to facilitate NLOS multi-channel establishment and signal propagation enhancement. Accordingly, the smokescreen should exhibit configurable emission wavelength, high emission efficiency, excellent floatability, high stability and low biotoxicity. We propose an encapsulated CsPbBr₃ nanocrystal tunable aerogel technology under aqueous atmospheric pressure, and evaluate its performance through indoor/outdoor experiments. The experimental results prove the feasibility of NLOS optical propagation enhancement and indication with fabricated materials. Specifically, ultraviolet (UV) light (266 nm) is projected onto the smokescreen and down-converted to two wavelengths in the blue (488 nm) and green (529 nm) spectrum, forming a tri-wavelength signal propagation channel and visualising the incident region as a colourful cloud. The light reception enhancement for UV light, blue light and green light reaches two, twenty, and ten-fold, respectively. The performance gain brought by the wavelength conversion is shown for two types of daily-use glasses. The proposed paradigm will significantly facilitate the development of optical communication and sensing in NLOS areas.