Sub-five-optical-cycle pulse generation from a Kerr-lens mode-locked Yb:CaYAlO4 laser

Direct generation of ultrashort few-optical-cycle pulses in various wavelength regions has attracted great attention in recent decades. In this paper, generation of less than five-optical-cycle pulses from a Kerr-lens mode-locked Y b : C a Y A l O 4 laser is demonstrated. Pumped by a 976 nm fiber laser, stable near-Fourier-transform-limited ultrashort soliton pulses centered around 1080 nm with a repetition rate of ∼ 113.7 M H z were obtained. The obtained pulses have a pulse duration as short as 17 fs if a S e c h 2 -shaped pulse profile is assumed, corresponding to about 4.68 optical cycles. To the best of our knowledge, this is the shortest pulse directly generated from mode-locked rare-earth-doped solid-state oscillators.