Random Lasers (RLs) and Random Fiber Lasers (RFLs) have been the subject of intense research since their first experimental demonstration in 1994 and 2007, respectively. These low coherence light sources rely on multiple scattering of light to provide optical feedback in a medium combining a properly excited gain material and a scattering disordered structure. It is the feedback mechanism which makes RLs/RFLs quite different from conventional lasers, with the later relying on an optical cavity usually formed by two static mirrors. This characteristic makes the RLs and RFLs devices to become cavityless, although not modeless, and present features of complex systems, whose statistics of intensity fluctuations are quite relevant. In addition, RLs can be designed in three-dimensional (3D) geometry, typically powders or colloids, in two-dimensional (2D) geometries, such as planar waveguides or thin-films, and one-dimensional (1D or quasi-1D) geometry, generally in optical fibers, known as the RFLs. The advantage of 1D geometry is the inherent directionality of the RFL emission, which otherwise is multidirectional in 3D geometry. In this review paper, we initially describe the basic theoretical framework supporting laser emission due to feedback in disordered structures. We then provide an updated vision of the types of RLs and RFLs that have been demonstrated and reported, from dyes solutions embedded with nano/submicron-scatterers composites to rare-earth doped micro or nanocrystals and random fiber Bragg gratings as the scattering structure. The influence of optical processes due to second-, third- and high-order nonlinearities on the intensity behavior of RLs are discussed. Subsequently, we review multidisciplinary studies that lead to the classification of RLs as complex systems exhibiting turbulence-like characteristics, photonic phase-transitions presenting replica symmetry breaking and intensity fluctuations satisfying Lévy-like statistics, and the so-called Floquet phase. Furthermore, we also highlight technological applications that includes sensing, optical amplification, and biomedical imaging. The review concludes pointing out potential directions in basic and applied research in the field of RL and RFL.

自 1994 年和 2007 年首次实验演示以来，随机激光器 (RL) 和随机光纤激光器 (RFL) 一直是深入研究的主题。这些低相干光源依赖于光的多次散射，以在结合了适当激发的增益材料和散射无序结构的介质中提供光反馈。正是反馈机制使 RL/RFL 与传统激光器大不相同，后者依赖于通常由两个静态反射镜形成的光腔。这一特性使 RL 和 RFL 器件变得无腔，尽管不是无模的，并且呈现复杂系统的特征，其强度波动的统计非常相关。此外，RL 可以设计为三维 (3D) 几何形状，通常是粉末或胶体，二维 (2D) 几何形状，例如平面波导或薄膜，以及一维 (1D 或准 1D) 几何形状，通常在光纤中，称为 RFL。1D 几何的优点是 RFL 发射的固有方向性，否则在 3D 几何中是多方向的。在这篇综述论文中，我们最初描述了由于无序结构中的反馈而支持激光发射的基本理论框架。然后，我们提供了已证明和报告的 RL 和 RFL 类型的更新视图，从嵌入纳米/亚微米散射体复合材料的染料溶液到稀土掺杂的微米或纳米晶体和随机纤维布拉格光栅作为散射结构。由于第二次，光学过程的影响，讨论了 RL 强度行为的三阶和高阶非线性。随后，我们回顾了多学科研究，这些研究导致将 RL 分类为具有类似湍流特征的复杂系统、呈现复制对称性破坏的光子相变和满足类 Lévy 统计的强度波动，以及所谓的 Floquet 相。此外，我们还强调了技术应用，包括秒传感、光学放大和生物医学成像。该评论总结指出了 RL 和 RFL 领域基础和应用研究的潜在方向。