Joshua E. Rothenberg
Optics Letters
A comparative study of the laser produced plasma (LPP) in vacuum at the surface of transparent crystalline α-Al2O3 (sapphire) and Al metal generated by 248-nm excimer laser pulses of 15-ns duration is reported. It was found that the threshold fluence for strong LPP emission in sapphire is 0.55 J/cm2, which is significantly lower than that needed for the same process in clean Al (1.7 J/cm2). At fluences higher than 4 J/cm2 the LPP emission from both targets is similar. The results obtained in sapphire require that its absorption coefficient increase by many orders of magnitude during the laser pulse. A possible explanation for the observed threshold difference is that the greater thermal diffusivity of Al more than compensates for its greater volatility; hence, a greater fluence is necessary to create the LPP in Al.
Joshua E. Rothenberg
Optics Letters
Joshua E. Rothenberg, D. Grischkowsky, et al.
IQEC 1984
Arunava Gupta, Gad Koren
Applied Physics Letters
Joshua E. Rothenberg, D. Grischkowsky
Journal of the Optical Society of America B: Optical Physics