Random cavity formation in an Er-doped fiber laser

The propagation of waves in random media, in particular, in complex dielectric media, whose refractive indices vary over length scales comparable to the wavelength, has been investigated intensively during the past few decades. In disordered materials light waves undergo multiple-scattering processes and are subject to unexpected interference effects, which lead to a variety of physical phenomena. Particularly interesting among them is the phenomenon of Anderson localization and its combination with amplification, which may lead to laser action with a random cavity. Random lasers can have unconventional properties, such as a very narrow spectral line output (H. Cao et al., 2000), and a low-threshold (V. Milner and A. Genack, 2005).