We present, to the best of our knowledge, the first demonstration of thermal, optical, and laser properties of Y b : G d S c O 3 for potentially efficient ultrashort pulse lasers. The stimulated emission cross section at 1025 nm (E//c) is 0.46 × 10 − 20 c m 2 with the emission band width of 85 nm, even broader than the well-known Y b : C a G d A l O 4 . It has quite a high thermal conductivity of 5.54 W / ( m ⋅ K ) at 50°C, comparable with Yb:YAG. In the continuous-wave regime, the maximum output power of 13.45 W at 1063.9 nm was generated with the optical-to-optical efficiency of 63.3%. These results suggest that the Y b : G d S c O 3 crystal is a promising candidate for ultrashort pulse lasers.

We demonstrate a 417 W, 175 kHz Innoslab chirped pulse amplification laser compressible to short and clean 406 fs pulse duration. A spectral bandwidth (full width at half maximum, FWHM) of ∼3 nm was maintained at full pump power, and the pulses exhibited good pulse quality in a wide tunable pulse energy range from 1.7 mJ to a maximum of 2.38 mJ. At the maximum output power, the compressed pulses were nearly pedestal free. The comprehensive effects of residual high-order dispersion from the front end, the gain shaping effects of the amplifier, and the slight mismatch of third-order dispersion (TOD) between the stretcher (CFBG) and the gating compressor, along with the small nonlinear phase shift accumulated in the amplifier, could have facilitated the high pulse quality. To the best of our knowledge, this is the shortest pulse duration from the Innoslab amplifiers at hundreds of watts average power in the millijoule energy regime.

We report on the investigation of continuous-wave (CW) and SEmiconductor Saturable Absorber Mirror (SESAM) mode-locked operation of a Yb:GdScO₃ laser. Using a single-transverse-mode, fiber-coupled InGaAs laser diode at 976 nm as a pump source, the Yb:GdScO₃ laser delivers 343 mW output power at 1062 nm in the CW regime, which corresponds to a slope efficiency of 52%. Continuous tuning is possible across a wavelength range of 84 nm (1027–1111 nm). Using a commercial SESAM to initiate mode-locking and stabilize soliton-type pulse shaping, the Yb:GdScO₃ laser produces pulses as short as 42 fs at 1065.9 nm, with an average output power of 40 mW at 66.89 MHz. To the best of our knowledge, this is the first demonstration of passively mode-locking with Yb:GdScO₃ crystal.

A high-power regenerative amplifier (RA) based on dual-slab Yb:KGd(WO₄)₂ (Yb:KGW) was demonstrated, which provided a maximum average power of 33.7 W at a repetition rate of 75–200 kHz before compression with a central wavelength of 1039 nm, corresponding to an optical-to-optical conversion efficiency of 51.4%. To the best of our knowledge, this is the highest average power from the Yb:KGW solid-state RA. The compressed pulse duration of 205 fs was realized under the maximum output power. By adjusting the gain of the crystals, respectively, the spectral shaping can be achieved. A combination spectrum with root-mean-square (RMS) bandwidth of 4.5 nm was generated with a central wavelength of 1035 nm at an output power of 20 W, the compressed pulse duration was 159 fs. Meanwhile, effective mitigation of thermal effects by dual-slab configuration guaranteed the nearly diffraction-limited beam quality: M _x ²= 1.17 and M _y ² = 1.20.

We demonstrate a gas-filled multipass cell (MPC) that cleaned the spatial mode of a spatial-filter-free 250 W, 100 kHz, 445 fs driven source based on an Innoslab amplifier and compressed the pulse duration to 41 fs simultaneously. The multipass cell acted as a spatial filter and benefited from its discrete waveguide nature, in which the input beam quality factor M² was improved from 1.53 to a near-diffraction-limited value of 1.21 at 96% transmission.

We demonstrate a high energy nonlinear pulse compression scheme based on a hybrid bulk-air multi-pass cell (MPC), achieving a high-power ultrafast source with 45 fs pulse duration, 130 W average power at 200 kHz repetition rate, and near-diffraction-limited beam quality. The impact of air nonlinearity accumulation in the MPC on beam quality is investigated to maintain good beam quality at high pulse energy, which suggests the adoption of pre-chirped and circularly-polarized pulses can effectively improve the input pulse energy and suppress the spatial quality degradation. The nonlinear mode-matching is also adopted to minimize the impact of the self-focusing effect of solid-thin-plates on q-preserving propagation. Although both solid plates and air contribute to the spectral broadening, the hybrid MPC is still an all-solid-state configuration without a pressure-controlled cell, providing a compact and economical approach for the nonlinear pulse compression at several hundred microjoules (µJ) energy levels. To the best of our knowledge, this is the highest pulse energy from the solid-state MPC configuration.