title: Fiber coupler for mode selection and high-efficiency pump coupling.
abstract: A pump/signal fiber coupler with functions of pump light coupling and high-order-mode suppression is reported. This coupler is composed of pump fibers and a double-clad fiber (DCF) with high pump-coupling efficiency. The core of DCF is microdeformed in the coupling region, which serves mode selection. Theoretical analysis and experimental results verify these functions. In the experiment, the pump-coupling and signal-transmitting efficiency of the coupler were ~98% and ~96%, respectively. This coupler can prevent mode distortion with fundamental mode launching, and improve the fiber laser beam quality with high-order-mode launching.
authors.affiliation: Center for Photonics and Electronics, State Key Laboratory of Tribology, Department of Precision Instruments and Mechanology, Tsinghua University, Beijing, China.
authors.forename: Qirong
authors.initials: Q
authors.lastname: Xiao
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.forename: Haichui
authors.initials: H
authors.lastname: Ren
authors.forename: Ping
authors.initials: P
authors.lastname: Yan
authors.forename: Mali
authors.initials: M
authors.lastname: Gong