Influence of the pulse duration on laser-induced mechanical effects

Mechanical effects induced by laser pulses with nanosecond to microsecond duration are studied on an optical fiber as a model target. The strength of the mechanical effects is documented by monitoring the stresses induced on the target fiber and the pressure transients detected in its direct environment. Pressure transients and stresses are detected during the laser pulse and some hundreds of microseconds later at the collapse of the resulting cavitation bubble. For microsecond pulse duration, the largest induced stress is observed at the cavitation bubble collapse. For nanosecond duration already a very large stress is observed during the laser pulse, followed by a second large stress. A continuous transition between the two regimes is observed for intermediate pulse duration, as also confirmed by the pressure measurements.