Movement of a bubble inside silica glass and calcium fluoride by irradiation of femtosecond laser pulses

摘要

Many researchers have investigated the interaction of femtosecond laser pulses with a wide variety of materials. The structural modifications both on the surface and inside the bulk of transparent materials have been demonstrated. When femtosecond laser pulses are focused into glasses with a high numerical-aperture objective, voids are formed. We report first observation that a bubble, which is called void moves under irradiation of femtosecond laser pulses inside silica glass and calcium fluoride. In situ observation reveals that the void moves towards incident direction of laser pulses as long as 5 micron by successive laser pulses without any mechanical translations.