Emergence of Exotic Spatio-Temporal Structure under Photon Flux

The operation of laser focusing on an object implies the creation of dielectric dielectric field under a thermodynamically open condition. Thus, we can expect the appearance of the effect of thermal irreversibility, such as breakdown of detailed balance, occurrence of circular state-flux in the phase-space, and limit-cycle oscillation. In the present article, we describe our recent experimental results on various kinds of exotic time-dependent phenomena induced by the continuous irradiation of laser. 1) Generation/annihilation of droplets from binary homogeneous liquid induced by laser: It will be shown that focused laser induces microphase separation on an oil/water isotropic solution. By choosing the proper experimental conditions, rhythmic change of generation, growth, and disappearance of a droplet at the focus is generated. This rhythmic phenomenon is a kind of limit-cycle oscillation. 2) Positive/negative photophoresis on a droplet: We show that a droplet is driven by a laser beam, either toward and backward along the direction of photon flux, through the change of the position of irradiation. Such photophoretic motion is induced by interfacial instability owe to the laser irradiation. 3) Rhythmic growth and bursting of a cluster with micro-beads: It is shown that negatively charged micro-beads are collected toward the focus of IR laser, i.e., optical tweezers. When the focusing angle is decreased from usual conditions, rhythmic change of the formation-growth-bursting of the beads cluster is generated.