Enhancing Solar-Blind UVC Communication With CsPbBr₃ Nanocrystals and Optical Concentrators

Optical wireless communication (OWC), especially UVC-based links, is gaining attention for its robustness against channel misalignment and solar-blind selectivity. However, large field-of-view optical concentrators, such as fused fiber-optic taper (FFOT) and compound parabolic concentrator (CPC), designed to achieve high modulation bandwidth and signal-to-noise ratio (SNR) at the receiver side, face limitations in UVC OWC systems due to low UV transmission efficiency. To address this challenge, we report on incorporating a UV-to-green wavelength-converting layer made of CsPbBr3 nanocrystals (NCs) in front of the optical concentrators to enhance the signal intensity at the receiver end. The reported design provides gain enhancement values for the received intensity of up to 3900% for the FFOT at an incidence angle of 40° and up to 780% for the CPC at an incidence angle of 60°. Furthermore, we established a UVC-based OWC system using a 278-nm LED, a CPC with the CsPbBr3 NCs layer, and an orthogonal frequency-division multiplexing (OFDM) modulation scheme. At a 60° angle-of-incidence, the system achieves a data rate >35 Mbit/s, SNR >8 dB, and BER below HD-FEC limit for a 48 Mbit/s data rate, significantly outperforming a similar UVC OWC system without the CsPbBr3 NCs layer.