Optical vortex possesses an annular intensity profile and an optical orbital angular momentum arising from its helical wavefront. In particular, it is noteworthy that optical vortex can twist the irradiated materials, such as silicon, metal, and polymer, to form chiral structures.
In this paper, we report on a spatial symmetry breaking of optical vortex propagating through bacteriorhodopsin (bR) suspensions. A 1 µm picosecond optical vortex mode propagated through bR suspensions (concentration: ~10 µM diluted in a 16 % NaCl solution) was broken into a twin mode with two bright spots. Also, the twin mode rotated towards a clockwise or counter-clockwise direction assigned by the handedness of the incident optical vortex mode. The rotation speed of the twin mode was measured to be 0.05 cycle/second. It was worth mentioning that such symmetry breaking of the optical vortex mode manifests an interaction between a helical wavefront and a helical bacteriorhodopsin. In fact, this phenomenon was never observed by using a NaCl solution without bacteriorhodopsin.
We discover that 1.06 μm picosecond vortex pulses induce chiral mass-transport to form a single-armed chiral surface relief in azo-polymer through two photon absorption process. The surface relief exhibits a diameter of a 2.5μm, i.e. 0.7 times of diffraction limit.
Optical beams with Orbital Angular Momentum (OAM) can potentially be used to probe forbidden transitions. However, the size of the vortex beam has to be comparable to that of an atom, molecule or an artificial atom. We propose and demonstrate a de-magnifying hyperlens allowing reducing the size of the vortex beam to the nanometer scale.
We discovered that a helical surface relief can be created in azo-polymer film merely by the irradiation of circularly-polarized
light without any orbital angular momentum. The chirality of the surface relief was also determined by the
handedness of the circular polarized light.