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• Chinese Optics Letters
• Vol. 20, Issue 2, 021401 (2022)
Zhixian Li1, Min Fu1, Xiaofan Zhao1, Hongye Li1, Zilun Chen1、2、3、*, Zefeng Wang1、2、3、**, and Jinbao Chen1、2、3
Author Affiliations
• 1College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
• 2State Key Laboratory of Pulsed Power Laser Technology, Changsha 410073, China
• 3Hunan Provincial Key Laboratory of High Energy Laser Technology, Changsha 410073, China
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Zhixian Li, Min Fu, Xiaofan Zhao, Hongye Li, Zilun Chen, Zefeng Wang, Jinbao Chen. Fabrication of side pump combiners when pumping with a laser diode and a fiber laser[J]. Chinese Optics Letters, 2022, 20(2): 021401 Copy Citation Text show less

Abstract

Side pumping combiners are widely used in fiber laser schemes for their high coupling efficiency, low insertion loss, and multi-point pumping capability. However, side pumping combiners perform differently in coupling efficiency when pumping with a laser diode (LD) and a high-brightness 1018 nm Yb-doped fiber laser (YDFL). In this paper, for the first time, to the best of our knowledge, we investigated the different parameters to fabricate the $(2+1)×1$ combiner with high coupling efficiency when pumping with an LD and a YDFL, respectively. After optimization, the maximum coupled pump power from one single-pump port of the combiner was 1200 W and 2730 W when pumping with a LD and a YDFL, respectively.

1. Introduction

Fiber laser sources have attracted more and more attention due to their high conversion efficiency, good beam quality, compact structure, and convenient thermal management[13]. As the crucial component of fiber lasers, a pump source can be mainly divided into laser diode (LD) pumping and Yb-doped fiber laser (YDFL) pumping, wherein the YDFL pumping has the advantages of low quantum deficit and high optical efficiency[4,5]. Nowadays, the power scaling of high-power fiber laser systems is mainly limited by stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), and transverse mode instability (TMI). Facts have proved that counter-pumping or bidirectional pumping schemes can help increase the threshold of SRS and TMI in fiber laser systems, thereby increasing the output power[6,7]. Side pumping combiners have many advantages when being used in the counter-pump scheme. First, the pump power is coupled through the side of the signal fiber, which can help to realize a multi-point cascade pump structure and improve the pumping capability of the laser system. Further, the signal fiber is uninterrupted throughout the manufacturing process, which is helpful to reduce the insertion loss and keep good beam quality. In addition, the high reverse pump isolation value of the side pump combiner can protect the pump source from power back propagation, making it more suitable for the reverse pump or bidirectional pump scheme[8].

Zhixian Li, Min Fu, Xiaofan Zhao, Hongye Li, Zilun Chen, Zefeng Wang, Jinbao Chen. Fabrication of side pump combiners when pumping with a laser diode and a fiber laser[J]. Chinese Optics Letters, 2022, 20(2): 021401