An Electro‐Optical Kerr Device Based on 2D Boron Nitride Liquid Crystals for Solar‐Blind Communications

Achieving light modulation in the spectral range of 200–280 nm is a prerequisite for solar‐blind ultraviolet communication, where current technologies are mainly based on the electro‐luminescent self‐modulation of the ultraviolet source. External light modulation through the electro‐birefringence control of liquid crystal (LC) devices has shown success in the visible‐to‐infrared regions. However, the poor stability of conventional LCs against ultraviolet irradiation and their weak electro‐optical response make it challenging to modulate ultraviolet light. Here, an external ultraviolet light modulator is demonstrated using two‐dimensional boron nitride LC. It exhibits robust ultraviolet stability and a record‐high specific electro‐optical Kerr coefficient of 5.1 × 10⁻ 2 m V −2 , being three orders of magnitude higher than those of other known electro‐optical media that are transparent (or potentially transparent) in the ultraviolent spectral range. The sensitive response enables fabricating transmissive and stable ultraviolet‐C electro‐optical Kerr modulators for solar‐blind ultraviolet light. An M‐ary coding array with high transmission density is also demonstrated for solar‐blind ultraviolet communication.