Symmetry Breaking of Optical Vortex in Bacteriorhodopsin Suspensions

Optical vortex, possessing an annular intensity profile and an orbital angular momentum owing to its helical wavefront, has been widely investigated in versatile applications, including a laser scanning microscope, optical telecommunication, and optical manipulation. In particular, optical vortex can twist an irradiated material, such as metal, silicon, polymer, and even liquid resin, to form spiral-shaped structured materials on the micro/nano scale [1–3]. The spiralling direction of such structured materials is controlled by the handedness of the optical vortex, i.e. the twisting direction of a helical wavefront. In recent years, a laser-indeed bacteria-waveguide, in which the optical radiation force collects cyanobacteria into the beam to form an optical waveguide [4], has been discovered.