Abstract

Conventional lasers have the resonant cavity which determines the characteristics of lasing, while random lasers, without any resonant cavity, i.e. cavity-less, generate lasing via multiple disordered scattering within gain medium. Since the first random laser based on the strong scattering of powders was reported in 1994 [1], extensive studies on random lasers are excited [2], and its application to optical imaging is explored [3]. Recently, all-fiber-based random lasers were reported, in which random distribution of the refractive index along the length of the fiber induces Rayleigh scattering due to the inhomogeneity of the fiber medium, and conventional silica fiber is used as the gain/transmission medium, via Stimulated Raman Scattering (SRS) [4]. Such a random fiber laser (RFL) intrinsically provides good directionality and high power, thus offering a number of attractive features, such as incoherence [5], temperature-insensitivity [6], and simplicity [7], etc. Hence, the RFL based on the nature of fiber-optic medium disorder is becoming an important member in both the families of random lasers and fiber lasers [8]. In this paper, we provide an overview of the recent advances in RFLs as novel optical sources, including: (1) Tunable RFLs; (2) High-power RFLs; (3) Broadband RFLs; (4) Pulsed RFLs.

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