Photothermal formation and targeted positioning of bubbles by a fiber taper

A fiber taper-based method is proposed for formation and targeted positioning of bubbles in water. By launching a laser of 1.55-μm wavelength with an optical power of over 20 mW into the fiber taper, a microbubble was formed at the taper tip. The mechanism of growth and decay of the microbubble was discussed. With the assistance of a moveable bare fiber, a train of bubbles with controllable diameters from 10 to 600 μm was formed and transported by the moveable fiber. Alternatively, by only moving the fiber taper, the formed bubbles can be easily positioned at targeted positions.