Electronic plasma induced by a focused femtosecond pulse (130 fs, 800 nm) in fused silica was investigated by use of pump-probe technology. Pump and probe shadow imaging and interferometric fringe imaging were combined to determine electronic collision time tau in the conduction band, and tau was measured to be 1.7 fs at an electron density near 5 × 10^19 cm^-3. The lifetime of the electronic plasma is also measured to be ~170 fs by use of the time-resolved shadow imaging technique.
© 2005 Optical Society of America
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
(320.0320) Ultrafast optics : Ultrafast optics
(320.7130) Ultrafast optics : Ultrafast processes in condensed matter, including semiconductors
(350.5400) Other areas of optics : Plasmas
Quan Sun, Hongbing Jiang, Yi Liu, Zhaoxin Wu, Hong Yang, and Qihuang Gong, "Measurement of the collision time of dense electronic plasma induced by a femtosecond laser in fused silica," Opt. Lett. 30, 320-322 (2005)