Laser physics and laser optics

Investigation of the radiation mode composition of the multimode fiber laser based on measurement of its spectral characteristics

R. F. Yakupov^a, R. I. Shaidullin^b, A. I. Baranov<sup>c

a</sup> Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region
^b Kotelnikov Institute of Radioengineering and Electronics, Fryazino Branch, Russian Academy of Sciences
^c VPG Laserone, Fryazino

Abstract: The paper presents a method for determining the mode composition of the output radiation of a multimode fiber laser. Since different transverse modes are reflected from a multimode fiber Bragg grating at different wavelengths, then experimental measurement of the optical spectrum of laser radiation allows to determine both the presence of certain modes and the share of optical power in each of them. An experimental study of a multimode fiber laser doped with ytterbium and erbium ions showed that it maintains from 2 to 4 transverse modes depending on the pump power, while the fiber itself supports the propagation of 17 modes.

Keywords: fiber laser, multimode radiation, fiber Bragg grating, optical spectrum.

Received: 28.01.2025
Revised: 28.01.2025
Accepted: 05.05.2025

DOI: 10.61011/OS.2025.06.60915.7577-25

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