<i>Q</i>-switched mode-locked multimode fiber laser based on a graphene-deposited multimode microfiber

Jia-Wen Wu; Yu-Xin Gao; Xu-Bin Lin; Jin-Gan Long; Hu Cui; Zhi-Chao Luo; Wen-Cheng Xu; Ai-Ping Luo

doi:10.3788/COL202119.121402

Abstract

We report Q-switched mode-locked (QML) pulses generation in an Yb-doped multimode fiber (MMF) laser by using a graphene-deposited multimode microfiber (GMM) for the first time, to the best of our knowledge. The single-wavelength QML operation with the central wavelength tunable from 1028.81 nm to 1039.20 nm and the dual-wavelength QML operation with the wavelength spacing tunable from 0.93 nm to 5.79 nm are achieved due to the multimode interference filtering effect induced by the few-mode fiber and MMF structure and the GMM in the cavity. Particularly, in the single-wavelength QML operation, the fifth harmonic is also realized owing to the high nonlinear effect of the GMM. The obtained results indicate that the QML pulses can be generated in the MMF laser, and such a flexible tunable laser has promising applications in optical sensing, measuring, and laser processing.

Nowadays, the multimode fiber (MMF), which was overlooked for decades, is making a strong comeback since it can address plenty of long-standing issues relating to the single-mode fiber (SMF). For optical communication, based on the spatial division multiplexing technique^[1,2], MMF can enhance the transmission capacity through adding the mode degree of freedom. In addition, MMF can meet the ever-increasing demands for high power laser^[3] through increasing the mode area to reduce the nonlinear effects. Apart from the afore-mentioned applications, MMF also can be applied in imaging^[4,5], metrology^[6], quantum processing^[7], and spectroscopy^[8], to name a few. Meanwhile, MMF is also an ideal platform to investigate the complex nonlinear phenomena due to interaction between the transverse modes, such as ultrabroadband dispersive waves generation^[9,10], geometric parametric instability^[11–13], supercontinuum generation^[14–16], spatiotemporal light beam compression^[17], and beam self-cleaning^[18–22].