Abstract

Special laser applications ranging from laser material processing, especially micromachining, to medical applications, metrology and spectroscopy demand transform limited ps pulses, often synchronized with a fs source [1]. Here, we present spectral compression of fs pulses inside a regenerative Yb:YAG laser amplifier [2] generated by a mode-locked Yb:KGW oscillator (see Fig. 1a). For spectral shaping we used an intra-cavity monochromator (grating, imaging lens and slit), while temporal and spectral tunability is achieved by insertion of a movable slit in the Fourier domain. A tuning range between 1025 and 1033 nm in spectral domain and between 3 and 100 ps in temporal domain was demonstrated (see Fig. 1b). We verified that the achieved time-bandwidth product (TBP) for all pulse durations >10 ps were kept close to the minimum of 0.44 (for Gaussian shaped pulses, see Fig. 1c).

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