Thulasi S, Sivabalan S
Appl Opt. 2020 Aug 20;59(24):7357-7363. doi: 10.1364/AO.395356.
We demonstrate an all-fiber ytterbium (Yb)-doped mode-locked oscillator using a hybrid structure based on no-core fiber graded-index multimode fiber (NCF-GIMF) as the saturable absorber (SA). The proposed SA exhibits unique characteristics such as large-power tolerance, high modulation depth of 24.7%, and low saturation intensity of 11.01/, which help to achieve a stable mode-locking operation. The all-normal and self-starting oscillator generates stable ultrafast pulses with a repetition rate of 21.35 MHz, pulse energy/average output power of 120 pJ/2.7 mW, and a pulse duration of 2.4 ps at a central wavelength of 1034.2 nm. The output pulses are then dechirped to 300 fs using an external grating compressor and possess high stability with a radio frequency spectrum of 58 dB. These results show that the NCF-GIMF-based SA can be used as an effective photonic device for high energy wave breaking free pulse generation.
我们展示了一种全光纤掺镱（Yb）锁模振荡器，它采用基于无芯光纤渐变折射率多模光纤（NCF - GIMF）的混合结构作为饱和吸收体（SA）。所提出的饱和吸收体具有诸如大功率容限、24.7%的高调制深度以及11.01/的低饱和强度等独特特性，这有助于实现稳定的锁模操作。全正色散且自启动的振荡器在中心波长1034.2 nm处产生重复频率为21.35 MHz、脉冲能量/平均输出功率为120 pJ/2.7 mW且脉冲持续时间为2.4 ps的稳定超快脉冲。然后使用外部光栅压缩器将输出脉冲啁啾至300 fs，并具有58 dB射频频谱的高稳定性。这些结果表明，基于NCF - GIMF的饱和吸收体可作为一种有效的光子器件用于产生高能波破碎自由脉冲。
