Oscillating bubbles at the tips of optical fibers in liquid nitrogen

We report that a bubble with a radius of a few micrometers may be created at a precise location on a metal-coated optical fiber tip immersed in liquid nitrogen by microsecond optical pulses with peak powers of less than 20 mW. Dynamic optical measurements reveal that after termination of the optical pulse the bubble exhibits stable oscillations for several tens of microseconds, at frequencies up to several megahertz, as it slowly collapses.