Dynamic mode-switchable and wavelength-tunable Brillouin random fiber laser by a high-order mode pump
Jiangtao Xu, Longtao Wang, Longkun Zhang, Linping Teng, Zhengwei Zhang, Richard Roy Berko, Liang Zhang, Fufei Pang, Xianglong Zeng
Abstract
We experimentally investigate two schemes of Brillouin random fiber laser (RFL) by using high-order-mode (HOM) pump in a few-mode fiber (FMF). The core-mode conversion between LP 01 and LP 11 modes is obtained in the FMF by cascading long period fiber gratings (LPFG) working at the same wavelength region. Different transversal modes of stimulated Brillouin scattering (SBS) can be implemented based on broadband long period fiber gratings (LPFG) and acoustically induced fiber gratings (AIFG). The RFL base on two broadband LPFGs can obtain high purity LP 11 mode operating in the range of 1543 nm to 1565 nm. Moreover, the output mode can be dynamically switched between LP 01 mode, LP 11a mode and LP 11b mode by modulating frequency shift keying (FSK) signal of the AIFG. This work has potential application prospects in the fields of mode division multiplexing systems, speckle-free imaging, free-space optical communication, laser material processing.