Photothermal trapping of dielectric particles by optical fiber-ring.

The removal of dielectric particles and bacteria from water is an extremely important global issue, particularly, for drinking and sanitation. This work provides a demonstration of optical purification of water using an optical fiber-ring. The size of particles suspended in water for trapping is 2.08 μm in diameter and the wavelength of light used for inducing photothermal effect is 1.55 μm with a power of 97 mW. The fiber, 6 μm in diameter, was formed to a racket-shaped ring with a minimum diameter of 167 μm and a maximum one of 350 μm. Experiment indicates that the particles moved toward the ring with the highest velocity of 4.2 μm/s and are trapped/assembled in the center of the ring once the laser beam of 1.55-μm wavelength was launched into the fiber. With a moving of the fiber-ring, the trapped/assembled particles were moved and the water can be purified by removal of the particles.