An advantage of fiber lasers over other types include light is already coupled into a flexible fiber. The fact that the light is already in a fiber allows it to be easily delivered to a movable focusing element, which is important for laser cutting, welding, and folding of metals and polymers. Another advantage is high output power. Fiber lasers can have active regions several kilometers long, and so can provide very high optical gain. They can support kilowatt levels of continuous output power because of the fiber's high surface area to volume ratio, which allows efficient cooling. The fiber's waveguiding properties reduce or eliminate thermal distortion of the optical path, typically producing a diffraction-limited, high-quality optical beam. Fiber lasers are compact compared to rod or gas lasers of comparable power, because the fiber can be bent and coiled to save space. They have lower cost of ownership. Fiber lasers are reliable and exhibit high temperature and vibrational stability, extended lifetime, and maintenance-free turnkeyoperation. High peak power and nanosecond pulses enable effective marking and engraving. The additional power and better beam quality provide cleaner cut edges and faster cutting speeds.
Applications of fiber lasers include material processing (marking, engraving, cutting)  telecommunications, spectroscopy, medicine, and directed energy weapons. Fiber lasers are now being used to make high-performance surface-acoustic wave (SAW) devices. These lasers raise throughput and lower cost of ownership in comparison to older solid-state laser technology. Fiber laser can also refer to the machine tool that includes the fiber resonator.