Introduction to the Special Issue on Fiber Lasers

The sixty-two papers in this special issue focus on fiber lasers which are increasingly becoming the light source of choice for a large range of scientific and industrial applications thanks to their inherent technological advantages. The invited papers authored by worldrenowned research groups and promising scientists from all over the world present extended reviews on recent progress and significant perspectives on future research directions. The emergence of distinctive operation regimes and new materials for fiber laser systems such as random fiber lasers, and novel saturable absorbers based on two-dimensional layered materials is covered in this issue. Furthermore, this special issue covers a range of advances on theory and simulation, new design and fabrication, novel laser architectures and pumping methods, advanced fiber laser characterization methodologies, ultra-high power fiber lasers, mid-infrared fiber lasers and ultrafast fiber lasers. This issue also illustrates the versatility of the fiber laser platform for a broad range of newand emerging applications. For example, fiber lasers are being exploited in biophotonics, state-ofthe- art material processing and, supercontinuum and frequency comb generation, as well as being considered for the nextgeneration gravitational wave detection and key distribution.