Table of Contents
Early Development and Market Growth
When the first fiber laser systems were developed, they were relegated to low-power milliwatt applications. Early fiber lasers were mainly used in communications, but did not have applications in material processing as they could not be scaled to the powers needed for this industry. Due to an increase in interest in fiber optic technology and rapid developments of fiber lasers, such as ytterbium fiber lasers, the efficiency of tens of kilowatts is now possible. As the technology continues to develop, the initial cost of the fiber laser system declines, which has led to fiber lasers offering the lowest price per watt with the highest beam quality, resulting in a quickly growing market share in material processing applications.
Fiber Laser Technology and Active Medium
Fiber lasers are lasers that utilize an optical fiber doped with rare-earth elements as an active medium. Erbium, ytterbium, and neodymium are some of the most commonly used rare-earth elements in fiber lasers, like ytterbium-doped fiber lasers and erbium-doped fiber lasers. These elements have a useful energy level configuration that allows for a cheap diode laser pump source to be used to excite the medium, e.g., erbium can absorb photons at 980 nm, which then decays to a metastable state at 1550 nm.
Advantages of Diode Laser Pump Source
A diode laser pump source is convenient due to the multiple advantages that it provides: it is cheap, efficient, and can be stacked. High-power fiber lasers are advantageous to many industries, especially material processing that includes laser cutting, laser engraving, laser welding, etc. There is no need to couple the laser output to a fiber to direct it where it needs to go, as the lasing is occurring in the fiber. Therefore, the need for a complicated optical setup is removed. The laser output of the fiber lasers is high quality – it is very straight and doesn’t spread out – as it is being created in a relatively confined area of the core. The power of the laser beam is confined to a small spot size, which is important for material processing applications. Moreover, high-power fiber lasers are efficient with 70-80% power conversion, which implies fiber lasers are easy to cool, as not a lot of energy is lost to heat compared to other high-power lasers. High-power fiber lasers have a long operating life of around 1 million hours, high peak power, and long pulse duration; these characteristics are essential for high-speed marking and cutting applications.