Chinese Optics Letters, Volume. 20, Issue 7, 071402(2022)

High repetition rate actively mode-locked Er:fiber laser with tunable pulse duration

Gang Yao1, Zhigang Zhao1,2, Zhaojun Liu1, Xibao Gao1, and Zhenhua Cong1、*
Author Affiliations
  • 1School of Information Science and Engineering, and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Qingdao 266237, China
  • 2State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Taiyuan 030006, China
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    An actively mode-locked fiber laser with controllable pulse repetition rate and tunable pulse duration is presented, in which an optical delay line (ODL) is used to adjust the cavity length precisely for regulating the repetition rate, and a semiconductor optical amplifier (SOA) is introduced for enabling the pulse duration control. Experimentally, continuous tuning of the repetition rate from 2 GHz to 6 GHz is realized, which is limited by the availability of an even higher repetition rate radio-frequency (RF) source. Specifically, when the repetition rate is fixed at 2.5 GHz, the pulse duration can be tuned from 4 ps to 30 ps, which is, to the best of our knowledge, the widest tuning range of pulse duration ever achieved in a gigahertz (GHz) repetition rate actively mode-locked 1.5 µm fiber laser oscillator.


    1. Introduction

    Ultra-short pulse lasers with high repetition rates are widely used in nonlinear frequency conversion, lidar, optical frequency combs, and material micro-processing[14]. Thus far, mode-locking has been well understood and developed as an important method for the generation of ultra-short optical pulses, including passive mode-locking and active mode-locking. Comparatively speaking, passive mode-locking is simpler in structure and can be realized by both real absorbers[5,6] and Kerr-effect-based artificial saturable absorbers[7], with which, however, it is not that easy to generate ultra-high repetition rate (>1GHz) pulses because of the requirement of very short cavity length, although it is not impossible. In contrast, active mode-locking is more straight-forward for high repetition rate generation, which usually works at the harmonic mode-locking state and is based on the employment of electro-optical modulators or acoustic-optical modulators. In addition, the pulse repetition rate can be tunable and controlled by the adopted radio-frequency (RF) sources.


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    Gang Yao, Zhigang Zhao, Zhaojun Liu, Xibao Gao, Zhenhua Cong. High repetition rate actively mode-locked Er:fiber laser with tunable pulse duration[J]. Chinese Optics Letters, 2022, 20(7): 071402

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    Paper Information

    Category: Lasers, Optical Amplifiers, and Laser Optics

    Received: Jan. 4, 2022

    Accepted: Apr. 22, 2022

    Published Online: May. 26, 2022

    The Author Email: Zhenhua Cong (



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