报道了一种工作于全正色散(ANDi)区,具有自由耦合输出特点,腔型结构极为简单的高功率被动锁模飞秒光纤激光器。该激光器利用具有极低非线性系数的掺Yb3+双包层大模场面积光子晶体光纤作为激光增益介质,光纤一端打磨成光滑的0°角作为一端腔镜及自由耦合输出端,提供4%的反馈光用于维持腔内激光振荡。利用半导体可饱和吸收镜(SESAM)启动并维持稳定锁模,直接输出得到平均功率2.5 W,脉冲宽度2 ps的高功率超短脉冲,对应单脉冲能量44 nJ,脉冲经腔外压缩至430 fs。 A high power passive mode-locked femtosecond fiber laser with free-coupling output and very simple cavity structure is reported in the ANDi region. The laser uses a Yb3 + double-clad large mode-field photonic crystal fiber with a very low nonlinear coefficient as the laser gain medium. One end of the optical fiber is polished to a smooth 0 ° angle as one end-endoscope and a free-coupling output end, providing 4% Feedback light is used to maintain intracavity laser oscillation. Using a semiconductor saturable absorption mirror (SESAM) to start and maintain a stable mode-locked mode, a high-power ultrashort pulse of average power 2.5 W and pulse width 2 ps was directly output, corresponding to a single pulse energy of 44 nJ, and the pulse was compressed extravagantly to 430 fs .