Lasers require a gain medium, i.e. something to hold the atoms and/or molecules that are being used to generate light. The gain medium can be made from a variety of materials and also take a variety of shapes. One such shape is a long very narrow cylinder. Another name for this shape is a fiber. If it’s very transparent and has the proper cladding we can call this an optical fiber. If it had the proper doping we can make this into a laser. Fiber lasers have advantages and disadvantages over other kinds of lasers. So depending on your application a fiber laser may be a good fit or not.
