Wang Teng, Jung Yongmin, Horak Peter, Zeng Xianglong, Richardson David J
Appl Opt. 2021 Oct 10;60(29):9007-9011. doi: 10.1364/AO.432051.
We experimentally demonstrate a passively mode-locked fiber ring laser using a small-core fiber-graded index multimode fiber-single-mode fiber (SCF-GIMMF-SMF) structure as an effective saturable absorber based on the nonlinear multimode interference (NL-MMI) effect. A small-core fiber is used as an input single-mode fiber to improve the coupling of power into higher-order modes in a multimode fiber and to enhance the modulation depth of the structure. Stable fundamental mode-locked operation is obtained at a pump threshold of 166 mW and the output soliton pulses have a 647 fs duration at 1557.96 nm with a 5.2 nm spectral width at a repetition rate of 19.37 MHz. This NL-MMI SA can be applied to high-power mode-locked fiber lasers owing to its inherent high damage threshold, compact size, wavelength independent operation, and fabrication simplicity.
我们通过实验证明了一种被动锁模光纤环形激光器，它使用小芯光纤-渐变折射率多模光纤-单模光纤（SCF-GIMMF-SMF）结构作为基于非线性多模干涉（NL-MMI）效应的有效饱和吸收体。小芯光纤用作输入单模光纤，以改善功率耦合到多模光纤中的高阶模，并增强结构的调制深度。在166 mW的泵浦阈值下获得了稳定的基模锁模运转，输出孤子脉冲在1557.96 nm处的持续时间为647 fs，在重复频率为19.37 MHz时的光谱宽度为5.2 nm。这种NL-MMI饱和吸收体因其固有的高损伤阈值、紧凑尺寸、波长无关操作和制造简单性，可应用于高功率锁模光纤激光器。
