Abstract

We have observed substantial hard x-ray emission from a high-power femtosecond laser-produced plasma. The laser is based upon chirped pulse amplification in Ti:sapphire, and produces 60-mJ 125-fsec pulses at 10 Hz at 807 nm. This output is focused onto a heavy metal in vacuum. The focused intensity is approximately 5 × 10¹⁷ W/cm², with a repetition rate of 10 Hz. We estimate an incident laser energy to x-ray energy conversion efficiency of ~10^-5 when gold is the target material. The conversion efficiency includes only those x-rays that pass through 4.7 mm of aluminum (photon energy greater than ~35 keV). We have demonstrated that this is a sufficient number of x-ray photons (~1 μJ) to record an x-ray shadowgraph with one laser shot. We anticipate that the x-ray pulse duration is similar in time duration to the driving laser pulse.

© 1991 Optical Society of America