High-Order Harmonic Generation from Solid Surface Plasmas by a Picosecond Pulse Laser

摘要

Investigations have been performed on harmonic generation from solid-vacuum interfaces using a prepulse-free 2.2-ps, 1054nm laser pulse at maximum intensities of ～ 1 × 10~(15)W · cm~(-2). The harmonic intensities were strongest for p-polarized pump, and decreased to about 50% in the case of s-polarized pumps. The ratio I_(4ω)/I_(2ω), between the intensities of the fourth and second harmonics was 0.25 at Iλ~2 = 6 × 10~(14)W · cm~(-2) · μm~2, and were found to be relatively large as compared with simulations. The harmonics are collimated in the specular direction, with a transverse mode and divergence comparable to that of the driving laser.