High power mode-locked erbium–ytterbium doped fiber laser using GIMF–SIMF–GIMF fiber structure as saturable absorber

Generation of Different Mode-Locked States in Nonlinear Multimodal Interference-Based Fiber Lasers

“…This means that when the pulse intensity reaches this region, it is clamped due to the peak power clamping effect, preventing its amplitude from increasing further and forming a flat peak [10,30]. Unlike previous reports [20][21][22][23][24][25][26][27][28][29], the distributed large-core GIMF-based scheme not only facilitates the excitation of more higher-order modes and the removal of the length limitation, but more importantly, it can be beneficial in resisting fragmentation and providing a versatile transfer curve with a wide range of tuning capabilities. In principle, the coupling of two GIMF transfer functions can, under certain conditions, provide richer and more complex properties such as oscillations and associated saturation/reverse saturation absorption phenomena, expansion or contraction of the modulation period, and a wide range of tunability of the modulation depth.…”

“…Subsequently, such an approach has been demonstrated experimentally [15][16][17][18][19][20][21]. Researchers solved the problem of the strict length limitation through several innovative methods such as adding a segment of step-index multimode/no-core fiber ahead of the GIMF [22][23][24][25], introducing an inner micro-cavity in the GIMF [26], stretching the GIMF [27][28][29], offset-splicing the GIMF [30,31], coiling the GIMF [32], etc. Through these methods, more high-order modes in the GIMF can be excited, and the mode field distribution can also be reconstructed, both of which lead to a reshaping of the transmission, thus removing the length limitation of the GIMF.…”