Fiber laser

multimode

Fiber lasers have made huge advances in the last 2 years. While they have not gained widespread acceptance as an industrial tool, they show promise for some new applications. Their current primary use is in low-power applications. With a smaller footprint than other laser types, they are also very modular. Because the laser cavity is a conventional multimode fiber, small diameter fiber delivery is inherent to the system, and no air-to-fiber coupling losses result. And, at an emission wavelength of 1.07 μm, there is relatively low loss in the fiber. The fiber is typically made of fused silica, doped with Ytterbium (Yb), pumped by diode laser stacks, and capped by fiber Bragg gratings. With multiple layers of pig-tailed, single-emitter diode lasers, the laser is scalable beyond 10 kilowatts. The primary disadvantage to the fiber laser is the high cost of the many diode stacks (since single emitters currently can achieve only about 4 watts of power) and related reliability issues. The key to overcoming uncertain diode lifespan is redundancy, which will mask diode stack failure, although this further increases the cost and complexity of those laser systems. Fiber lasers offer the preferred wavelength range for metal processing due to high material absorption. The 300-μm fiber also provides a very straight-sided beam profile, which is good for welds and extended depth of focus. A primary benefit to fiber lasers is their delivery via thin fiber, which can be manipulated using inexpensive robots.