Amphibian-like Flexible Organic Crystal Optical Fibers for Underwater/Air Micro-Precision Lighting and Sensing.

Visible light guiding optical fibers with underwater operational capability are highly desired for subaquatic communication and sensing technologies. Herein, we present mechanically flexible, blue-violet fluorescent (4,4'-bis(2,6-di(1H-pyrazol-1-yl)pyridin-4-yl)biphenyl) (BPP) crystal waveguides with high-aspect ratio. These milli-meter-long BPP crystals guide light actively and passively in ambient and underwater conditions demonstrating their amphibian-like character. Due to the crystal's high flexibility, the optical fiber's output light direction in submerged and ambient states can be altered mechanically for high-precision lighting and sensing applications. The development of such multi-environment-compatible and mechanically flexible organic optical fibers acting as sensing materials possess enormous potential for short-range underwater photonic technologies.