Micromechanically‐Powered Rolling Locomotion of a Twisted‐Crystal Optical‐Waveguide Cavity as a Mobile Light Polarization Rotor

We demonstrate mechanically‐powered rolling locomotion of a twisted‐microcrystal optical‐waveguide cavity on the substrate, rotating the output signal's linear‐polarization. Self‐assembly of (E)‐2‐bromo‐6‐(((4‐methoxyphenyl)imino)methyl)‐4‐nitrophenol produces naturally twisted microcrystals. The strain between several intergrowing, orientationally mismatched nanocrystalline fibres dictates the pitch lengths of the twisted crystals. The crystals are flexible, perpendicular to twisted (001) and (010) planes due to π⋅⋅⋅π stacking, C−H⋅⋅⋅Br, N−H⋅⋅⋅O and C−H⋅⋅⋅O interactions. The twisted crystals in their straight and bent geometries guide fluorescence along their body axes and display optical modes. Depending upon the degree of mechanical rolling locomotion, the crystal‐waveguide cavity correspondingly rotates the output signal polarization. The presented twisted‐crystal cavity with a combination of mechanical locomotion and photonic attributes unfolds a new dimension in mechanophotonics. Twisted organic crystals display rolling locomotion on a flat substrate when subjected to mechanical force using an atomic force microscope cantilever tip. These crystals are flexible and efficiently self‐guide the fluorescence both in straight and bent geometries and act as optical cavities. Remarkably, twisted‐crystal waveguides rotate the guided polarized optical modes direction as a function of the crystal's rolling motion.