Chang Shuo, Wang Hailong, Wang Zhaokun, Yang Hailong
Opt Express. 2021 May 10;29(10):14336-14344. doi: 10.1364/OE.425326.
We have demonstrated the generation of multicolor noise-like pulse complex in a passively Yb-doped mode-locked fiber laser based on a single mode-graded index multimode-single mode fiber (SMF-GIMF-SMF) device as the saturable absorber (SA). The stimulated Raman scattering (SRS) effect leads to the cascaded generation of the main noise-like pulse (NLP) at 1028.8 nm together with the noise like Raman pulse (RP) at 1076.1 nm. The generated dual wavelength pulses demonstrate the unique properties of mutually synchronization and coherence. The autocorrelation traces show that each of the synchronously mode-locked pulses exhibits a double-scale structure with a narrow peak which consists of a train of quasi-periodic beat pulses with a 35.7 fs pulse width and a pulse separation of about 77.2 fs. The total output power reaches 102.5 mW with 34% of it belonging to the RP. And furthermore, by separating the two pulses with spectral filters, the modulation fringes cannot be observed anymore. These results indicate that the Raman component participates in the mode-locking operation as a 'signal' instead of 'noise'. Such a coherent Raman pulse source provides a novel platform for numerous applications, such as frequency comb spectroscopy and so on.
我们已经证明，在基于单模渐变折射率多模-单模光纤（SMF-GIMF-SMF）器件作为饱和吸收体（SA）的被动掺镱锁模光纤激光器中，可以产生多色类噪声脉冲复合体。受激拉曼散射（SRS）效应导致在1028.8 nm处级联产生主要的类噪声脉冲（NLP）以及在1076.1 nm处的类噪声拉曼脉冲（RP）。所产生的双波长脉冲展现出相互同步和相干的独特特性。自相关轨迹表明，每个同步锁模脉冲都呈现出具有窄峰的双尺度结构，该窄峰由一系列准周期拍频脉冲组成，脉冲宽度为35.7 fs，脉冲间隔约为77.2 fs。总输出功率达到102.5 mW，其中34%属于RP。此外，通过用光谱滤波器分离这两个脉冲，再也观察不到调制条纹。这些结果表明，拉曼分量作为“信号”而非“噪声”参与锁模操作。这样一个相干拉曼脉冲源为众多应用提供了一个新颖的平台，如频率梳光谱学等。
