RANDOM-DISTRIBUTED FEEDBACK FIBER LASERS BASED ON RAYLEIGH SCATTERING
S. A. Babin1,2, I. D. Vatnik1
1Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences,
pr. Akademika Koptyuga 1, Novosibirsk, 630090 Russia
2Novosibirsk State University
ul. Pirogova 2, Novosibirsk, 630090 Russia
Keywords: fiber laser, distributed feedback, Rayleigh scattering, stimulated Raman scattering, random laser
Abstract
Single-mode optical fibers have been widely used in optical communications, and effective fiber lasers have been designed on the basis of active fibers with linear or ring cavities. In fiber lasers, the distance between the cavity mirrors can reach 270 km (the maximum length is determined by the linear attenuation and nonlinear dephasing of the waves). In 2009, random lasing was found in a long telecommunications fiber without any cavity: the positive distributed feedback required for lasing is due to Rayleigh scattering of light, and distributed amplification is provided by stimulated Raman scattering. Such a laser can be classified into the group of so-called random lasers, actively studied recently; the fiber geometry and the weakness of Rayleigh scattering provide much better output characteristics compared to the other types of random lasers. The lasing efficiency and beam quality of this laser are comparable to those of fiber lasers with a conventional cavity. At the same time, it has a number of unique features (unlimited length, and mode-free spectrum etc.), providing new physical phenomena and new opportunities for applications in telecommunications and sensor systems. The paper presents a review of recent results of studies in this area.
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