Post-compression of powerful femtosecond pulses after second harmonic generation

Abstract

A proof-of-principle experiment of highly efficient (38%) second harmonic generation was implemented at a ∼1TW/cm2 intensity of a 45 fs pulse in a composite nonlinear sample–a 1 mm KDP crystal glued onto a 1 mm fused silica substrate. The attenuated replica of the second harmonic pulse (455 nm) was compressed down to 28.6 fs by means of dispersive mirrors, with a significant reduction in both the wings and the far temporal contrast. The peak power of the second harmonic was ∼74% of the power of the fundamental harmonic, which ensured a three-fold increase in the focal intensity.