Wang Yiran, Su Xiancui, Willemsen Thomas, Zhang Bingyuan, He Jingliang, Zhang Baitao
Opt Lett. 2025 Aug 1;50(15):4830-4833. doi: 10.1364/OL.569306.
Pulse compression in Yb-doped lasers remains constrained by two critical bottlenecks: the narrow fluorescence spectrum of gain crystals and the inherently weak intracavity nonlinear spectral broadening effects. Here, through spectral-domain optimization of output coupler transmittance curves and using Yb:CALGO crystal as the gain medium, we have engineered enhanced output spectral bandwidth, enabling a 3.5-fold expansion in spectral bandwidth (Δλ = 323 nm at -10 dB) compared to the fluorescence spectrum. As a result, we achieved a Kerr-lens mode-locked Yb:CALGO oscillator with a pulse duration of 12.3 fs, approaching 3 optical cycles. It is the shortest, to the best of our knowledge, pulse duration ever generated directly from any type of Yb laser oscillators and rare-earth laser oscillators.
增益晶体的窄荧光光谱以及腔内固有的弱非线性光谱展宽效应。在此，通过对输出耦合器透射率曲线进行光谱域优化，并使用Yb:CALGO晶体作为增益介质，我们设计出了增强的输出光谱带宽，与荧光光谱相比，光谱带宽实现了3.5倍的扩展（在-10 dB时Δλ = 323 nm）。结果，我们实现了克尔透镜锁模Yb:CALGO振荡器，其脉冲持续时间为12.3 fs，接近3个光学周期。据我们所知，这是直接从任何类型的Yb激光振荡器和稀土激光振荡器产生的最短脉冲持续时间。
