Tunable 1.6–2 μm near infrared few-cycle pulse generation by filamentation

摘要

We present results on tunable few-cycle laser pulses generated in the near infrared region obtained by filamentation in a krypton cell combined with group velocity dispersion compensation in fused silica. We obtain a spectral broadening of a factor ～2–3 over the entire spectral domain studied. The central wavelength is tuned from 1.6?μ face='roman'>m to 2?μ face='roman'>m via an optical parametric amplification source. In optimum experimental conditions, where the input central wavelength is set to 1.7?μ face='roman'>m,?1.8?μ face='roman'>m, and 1.9?μ face='roman'>m, the incident power to the gas cell exceeded the critical power of Krypton by a factor of ～4 and the achieved spectral broadening covered ～300?nm. Using group velocity compensation in bulk fused silica, we obtain near infrared output pulses as short as 2–3 optical cycles with 200?μJ energy per pulse. This near infrared filamentation tunable few-cycle pulse source is an important achievement for strong field physics applications such as attoscience, where wavelength scaling has an important effect.