26 May 2021 Multimode oscillation Q-switched mode-locking fiber laser based on gain equalized few-mode Er-doped fiber
Jia Wei, Peng Zhang, Zhenxing He, Shuang He, Xiyu Gong, Yunlong Fan, Shoufeng Tong
Author Affiliations +
Abstract

We propose and demonstrate experimentally multimode Q-switched mode-locking (QML) fiber laser signal generation based on a long few-mode Er-doped fiber (FM-EDF). The erbium-doped profile of the fiber has been optimized to equalize the modal gain. The fiber supporting six modes has a total length of 5.5 m, a part of the fiber is used as a gain medium, and the unpumped part of the fiber is used as a saturable absorber. Multimode oscillation lasers in the state of the continuous wave laser operation, Q-switching, and QML state pulse laser operation were observed and measured at different pump powers by adjusting the polarization controller. A 1570-nm multimode QML pulse train was obtained, when the pump power was about 2.4 W. The width of the Q-switched envelope was 19  μs, and the repetition rate was 17.4 kHz. The stable mode-locked pulses repetition rate in Q-switched envelopes was 13.18 MHz. These temporal pulses can also be observed under the case of partly blocking the beam profile, and the part of the spectral signal gradually disappeared. The mode number in the laser was checked by a homemade mode selection photonic lantern. The results showed that the fiber laser had multimode oscillation, and the modes in generated signal were ≥5. The multiple transverse modes of the generated lasers are all in QML state at the same time. To the best of our knowledge, this is the first experimental demonstration of a multimode QML fiber laser using a long FM-EDF.

© 2021 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2021/$28.00 © 2021 SPIE
Jia Wei, Peng Zhang, Zhenxing He, Shuang He, Xiyu Gong, Yunlong Fan, and Shoufeng Tong "Multimode oscillation Q-switched mode-locking fiber laser based on gain equalized few-mode Er-doped fiber," Optical Engineering 60(5), 056108 (26 May 2021). https://doi.org/10.1117/1.OE.60.5.056108
Received: 10 November 2020; Accepted: 14 May 2021; Published: 26 May 2021
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Cited by 4 scholarly publications.
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KEYWORDS
Fiber lasers

Mode locking

Multimode fibers

Pulsed laser operation

Q switched lasers

Q switches

Continuous wave operation

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