Frequency tuning enhancement of few-cycle femtosecond laser pulses by double-pump-induced N _2 index modulation

摘要

Considering field-free molecular alignment enhancement by multiple pulses in the hollow fiber, we theoretically analyze how long-distance propagation influences the final alignment degree. Based on this, we propose a way to enhance frequency tuning of few-cycle femtosecond laser pulse by multi-pump-induced N2 index modulation. It is found that two pumps are optimized with parameters of 100 fs and 3 × 10 ~(13) Wcm ~(-2). The tuning range of the initial 5 fs 800 nm probe pulse by double aligning pumps is about twice that by a single pump.