Infrared and Laser Engineering, Volume. 49, Issue 10, 20200014(2020)

Study on signal light transmission efficiency enhancement of backward pump-signal combiners in high-power fiber lasers

Fang Zeyuan1,2, Yin Lu2,3, Yan Mingjian2, Han Zhigang2, Shen Hua2, and Zhu Rihong2,3
Author Affiliations
  • 1Shanghai Electro-Mechanical Engineering Institute, Shanghai 201109, China
  • 2MIIT Key Laboratory of Advanced Solid Laser, Nanjing University of Science and Technology, Nanjing 210094, China
  • 3School of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
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    In the manufacturing process of the backward pump-signal combiner (BPSC) in high-power fiber lasers, the core diameter of the output signal fiber becomes thinner after being tapered, and the mode field mismatch occurs when splicing with the input signal fiber, which decreases the signal light transmission efficiency of BPSCs. To solve this problem, a simulation model was established to simplify the relationship between transmission efficiency and the mode field mismatch. A test system was built to measure the signal light transmission efficiency of backward pump-signal combiners. Finally, a method was proposed to enhance the signal power transmission efficiency of the BPSC through optimizing the parameters of its signal fiber. Accordingly, a (6+1)×1 BPSC using customized 25/400 double-cladding fibers was fabricated with a pre-tapering method, and its signal light transmission efficiency was better than 98% after being tested. Using this combiner, a bi-direction-pumping master oscillator power amplifier (MOPA) fiber laser system was built, achieving a stable output of 3 kW.


    0 Introduction

    Fiber lasers have a broad application prospect in various fields for their excellent pump power conversion efficiency and beam quality, as well as the compact structure and simple thermal management. Recently, commercial fiber laser systems have emitted an output of tens of kilowatts through a master oscillator power amplifier (MOPA) structure[1]. In order to achieve a higher output power, the pump combiner (PC) and pump-signal combiner (PSC) are widely used, the requirements for their signal light transmission efficiency and stability are also increasing[2-4]. According to their structure and function, the combiners can be divided into N×1 PCs and (N+1)×1 PSCs. The former can couple multi-channel pump light into a signal fiber, mostly used in the forward-pumping structure of fiber oscillator, while the latter can couple signal light together with the multi-channel pump light into the signal fiber, to realize the signal light transmission and pump power injection of oscillator reverse-pumping structure and MOPA amplifier.


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    Zeyuan Fang, Lu Yin, Mingjian Yan, Zhigang Han, Hua Shen, Rihong Zhu. Study on signal light transmission efficiency enhancement of backward pump-signal combiners in high-power fiber lasers[J]. Infrared and Laser Engineering, 2020, 49(10): 20200014

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    Paper Information

    Category: Laser & laser optics

    Received: Jan. 2, 2020

    Accepted: --

    Published Online: Jul. 6, 2021

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