We demonstrate that a highly confined plasma inclusion is formed inside a micrometric water droplet that is excited by a femtosecond laser. An 800-nm laser pulse generates a plasma inclusion by laser-induced breakdown that is subsequently probed by the elastic scattering of a second (400-nm) time-delayed ultrashort pulse. For a 25-μm -radius droplet and an incident intensity of 7×1012 W/cm 2 the radius of the highly localized plasma is 1.9±0.4 μm . We probed the plasma formation dynamics on femtosecond time scales by varying the delay between the pump and the probe pulses. Good agreement with numerical simulations of the process was found.
© 2003 Optical Society of America
(140.3440) Lasers and laser optics : Laser-induced breakdown
(290.5820) Scattering : Scattering measurements
(320.2250) Ultrafast optics : Femtosecond phenomena
(320.7110) Ultrafast optics : Ultrafast nonlinear optics
(320.7130) Ultrafast optics : Ultrafast processes in condensed matter, including semiconductors
Fraçnois Courvoisier, Véronique Boutou, Catherine Favre, Steven C. Hill, and Jean-Pierre Wolf, "Plasma formation dynamics within a water microdroplet on femtosecond time scales," Opt. Lett. 28, 206-208 (2003)