OBSERVATION OF SOLID-DENSITY LAMINAR PLASMA TRANSPARENCY TO INTENSE 30 FEMTOSECOND LASER-PULSES

Near total transmission of 30 fs laser pulses through 0.1 mu m plastic foil targets has been observed for the first time at an intensity of 3 x 10(18) W/cm(2) in absence of precursor plasma. This level of trans mittivity is far above the level predicted by current theoretical mode ls or numerical simulations. The transmittivity was found to drop by 4 0 times at an intensity of 4 x 10(17) W/cm(2) and was within the exper imental background level at 5 x 10(16) W/cm(2). Our measurements stron gly suggest a new mechanism of propagation of electromagnetic waves th rough overdense plasmas. [S0031-9007(97)04356-1].