High-power 70 fs Yb:KGW oscillator with enhanced intracavity kerr-effect nonlinearity

We demonstrated a high-power, diode-pumped Yb:KGW Kerr-lens mode-locked laser featuring an intracavity Kerr-mirror configuration. The resonator is terminated with a coated YAG crystal serving as the nonlinear Kerr-mirror, which significantly enhances self-phase modulation. This configuration enables the generation of 80.5-fs pulses at 5.72 W output power at the central wavelength of ∼1030 nm, with further Kerr-effect nonlinearity optimization yielding 70.3-fs pulses at 5.06 W output power and a maximum broadening spectral width of up to 20.5 nm. Notably, this represents the first Yb:KGW Kerr-lens mode locked oscillator to exceed 5 W of output power while sustaining sub-100 fs pulse durations. This proposed Kerr-mirror-mediated approach establishes a new regime in ultrafast oscillator design, enabling the enhancement of power-scaling to multi-watt levels while delivering pulses of reduced duration.