High temporal contrast 1053 nm femtosecond pulses via spectral broadening and filtering in an air-filled multi-pass cell using a Yb:CALGO amplifier

Temporal contrast is crucial for the interaction of ultraintense, ultrashort pulse lasers with matter. Seed laser sources that offer high temporal contrast are essential for enhancing overall temporal contrast. In this study, we demonstrate the generation of a high temporal contrast seed laser by spectral broadening and filtering of a Yb: CALGO femtosecond amplifier in an air-filled multi-pass cell (MPC). The temporal contrast exceeds 10⁹ within 100 ps prior to the main pulse, with a pulse energy of 227 µJ and a duration of 118 fs. Given its excellent beam quality and stability, this laser source is well-suited as a high-quality seed for Nd:glass-based ultraintense laser facilities. This work achieves a remarkable internal efficiency of over 70% in generating a clean seed pulse for ultraintense lasers.