Prof. Jianqiu Cao
National University of Defense Technology, China
Title: Study on radiation-induced variation of TMI threshold of Yb-doped fiber amplifiers
Abstract:
Yb-doped fiber amplifiers have attracted much attentions because of their applications in various fields such as industry, material processing, and so on. In recent years, their performance in the radiation environment become an attractive topic. However, the radiation effect will do harm to the Yb-doped fibers, which can degenerate the output properties of Yb-doped fiber amplifiers. In this speech, the radiation effect on the transverse mode instability (TMI) of Yb-doped fiber amplifiers will be reported. TMI is a phenomenon inducing the transverse mode coupling of signal light, and thus can worsen the beam quality of fiber amplifiers. TMI has been considered as one key factor limiting the power of fiber amplifiers.
In this speech, our recent study on the radiation effect on TMI threshold will be given. Firstly, the background and motivation of our study will be introduced. Then, the formula predicting the radiation effect on TMI threshold will be presented, and the radiation-induced variation of TMI threshold will be discussed. The effect of radiation dose on the TMI threshold will be given. After that, the variation of TMI threshold will be compared with another radiation effect (i.e., the output power attenuation of fiber amplifiers), in order to reveal the dominant factor limiting the output power of irradiated Yb-doped fiber amplifiers. The radiation effect on the TMI-limited power of Yb-doped fiber amplifiers will also be discussed in brief at the end of this speech.
Biography:
Jianqiu Cao received the graduate degree in Applied Physics from Dalian University of Technology, China, in 2003, and his M.S. and Ph.D. in Optical Engineering from National University of Defense Technology, China, in 2005 and 2010, respectively. He joined the College of Optoelectronic Science and Engineering, National University of Defense Technology, in 2010 as a Lecturer and was promoted to an Associated Professor in 2016. Now, he is a Researcher in Optical Engineering in the College of Advanced Interdisciplinary Studies, National University of Defense Technology. His current research interests include high-power fiber lasers, nonlinear fiber optics, and advanced fiber design. This led to developments of super fluorescent fiber sources operating near 980 nm and 1060 nm, high-power Yb-doped fiber lasers operating near 980 nm, distributed side-coupled cladding-pumped fiber lasers, and thermal and nonlinear effect analysis in fiber lasers. He has co-authored more-than 100 publications in scientific journals and conference proceedings and holds 6 patents.