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High-power fiber lasers in laser processing
The major position in the laser processing field is rightly being given to the high-power fiber laser due to such qualities as high beam quality, energy efficiency, space efficiency, stability, and reliability. The fiber laser is a laser that uses an optical fiber as the active medium, which usually has a rare-earth-doped core. The major active element used in the fiber lasers for material processing is ytterbium. This element provides light absorption (available for pumping) at wavelengths of 900-1000 nm, and fluorescence that causes laser oscillation lies at 1000-1100 nm.
Market growth and performance improvements
Over the last decade, the performance advanced in high-power fiber lasers has been particularly impressive. It is making high-power fiber lasers a successful, fast-increasing commercial business currently worth $800 M/year, with a compound annual growth rate of about 13%, which is the highest among the different laser technologies. The fiber technology has grown quite diverse and mature, and can provide an excellent platform for fabricating result, high-performance laser systems. The core and cladding structures can be tailored appropriately to control the beam modality, optical nonlinearities, and the power.
Features and advantages of high-power fiber lasers
High-power fiber lasers are much more progressive and promising than traditional lasers using solids or gases as the active medium in many aspects. To ensure the high beam quality of fiber lasers, it is necessary to select the appropriate core diameter and the difference in relative refractive indices, which can reduce the number of transverse modes. The CO2 laser also provides a high beam quality. In addition to this, fiber lasers and fiber laser systems based on a thin optical fiber with a diameter of several hundred micrometers as the active medium can be easily cooled, thereby attaining high power output while maintaining laser beam quality.
High-power fiber lasers have very low loss of pump and laser light because they are both confined and guided in the low-loss fiber core. The high quantum efficiency of ytterbium serving as the active element leads to 60-70% efficiency in energy conversion from pump light to laser light. Fiber laser systems achieve a high output power with a high energy conversion efficiency while maintaining a high beam quality. Owing to the very high energy conversion efficiency and a resonator consisting of fine fiber and small optical components, high-power fiber lasers have a far smaller heat dissipation mechanism and power supply, and thus far smaller overall dimensions and weight than traditional high-power lasers. These lasers constructed by fusion-splicing optical fibers are not influenced by vibration, shock, or temperature changes, and therefore have stable output power and stable high beam quality. Besides the above-mentioned factors, high-power fiber lasers are practically maintenance-free due to the fact that the paths of the beam are not exposed to the atmosphere.