A water contact glass@PiG film color converter with superhigh brightness and ultralong durability for wide-area underwater lighting and communication

Abstract

Laser-driven light possesses exceptional brightness, rendering it particularly suitable for underwater lighting (UL) and underwater wireless optical communication (UWOC). However, achieving high-brightness light remains a challenge due to significant luminescence quenching in color converters caused by heat accumulation from high-power laser excitation. This study proposes an innovative approach for utilizing laser lighting in UL and UWOC applications by directly immersing color converters in water to eliminate thermal-induced luminescence saturation. To develop color converters capable of prolonged contact with water, we significantly enhanced the water stability of a Y₃Al₅O₁₂:Ce phosphor-in-glass (PiG) film through Si–N co-doping and a novel waterproof structure. Due to direct contact with water, the underwater illuminance of the PiG film could reach as high as ∼2.94 × 10⁵ lux at a distance of 15 cm from the source under 34.9 W mm⁻² blue laser excitation, with no luminescence saturation observed. Due to the optimized phosphor stability and waterproof design, the illuminance of the PiG film remained at 98.56% and 98.70% of its original intensity after 50 days in clear water and seawater, respectively. Finally, a portable underwater laser light source with a 60° divergence angle was developed in a simple transmissive excitation mode based on the PiG film. This light source could illuminate wide-area underwater environments at distances exceeding 20 m and facilitate wide-area UWOC over distances greater than 40 m. These findings pave the new way for the commercial application of laser-driven lighting devices in wide-area UL and UWOC.