Femtosecond damage threshold at kHz and MHz pulse repetition rates

Femtosecond laser-induced damage threshold (LIDT) measurements for different optical components are well studied for a set of laser pulse repetition rates spanning the range between 1 Hz and 1 kHz. Recent years saw the advent of high-repetition-rate femtosecond systems with relatively high pulse energy. Therefore investigation of LIDT in the MHz region is essential. We performed several comparative femtosecond LIDT measurements on typically used ultrafast optical elements with different Ti:Sapphire laser systems having substantially different pulse repetition rates (a 1 kHz regenerative amplifier and a 4.3 MHz long-cavity oscillator) and found a substantially lower MHz LIDT threshhold.