Generation of a carrier-envelope-phase-stable femtosecond pulse at 10 µm by direct down-conversion from a Ti:sapphire laser pulse

Abstract

We report the generation of a carrier-envelope-phase-stable femtosecond pulse at 10 µm with 800 nJ by the down-conversion of a 25-fs-long 800 nm pulse with 1.2 mJ obtained from a standard Ti:sapphire regenerative amplifier. We discuss a simple optical setup for the spectral broadening of the 800 nm pulse by filamentation in air and the intrapulse difference frequency generation in a wide-bandgap nonlinear optical crystal, LiGaS2. From the measurement of the electric-field waveform of the generated mid-infrared pulse by electrooptic sampling, the maximum electric-field amplitude is estimated to be approximately 11 MV/cm at a beam diameter of 70 µm.