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.

We report on, to the best of our knowledge, the first $Q$-switched single-crystal fiber (Ho:YAG SCF) laser in the 2 μm spectral range, in-band pumped by a Tm-doped all-fiber laser. A continuous-wave laser with 12.5 W output power and $Q$-switched laser with 1.44 mJ pulse energy and 7.5 ns pulse duration at a repetition rate of 1 kHz were demonstrated. The high laser performance is attributed to the high gain, suppressed nonlinear effects, and easy thermal management which benefited from the unique geometric construction of the SCF.

We report on a diode-end-pumped high-power and high-energy Nd:YAG single-crystal fiber laser at 1834 nm. Two 808 nm diodes injecting about 58 W pump power into the Nd:YAG fiber have generated 3.28 W continuous-wave and 1.66 W Cr:ZnSe-based passively $Q$-switched lasers. Slope efficiencies with respect to pump powers are 8.7% for the continuous-wave laser and 4.9% for the $Q$-switched laser. The extracted maximum pulse energy is about 266.9 μJ, and the corresponding maximum pulse peak power is 2.54 kW. These performances greatly surpass previous results regarding this specific laser emission because the laser gain medium in the form of fiber can significantly mitigate thermally induced power saturation thanks to its significantly reduced thermal lensing effect. Single-crystal fiber lasers show great potential for high average power, pulse energy, and peak power.