A fibre laser is a solid-state laser that has optical fibre properties. Fibre lasers are usually built for marking and engraving applications in accordance with the MOPA principle. MOPA means that a “master oscillator” (MO) is intensified using a “power amplifier” (PA). The master oscillator is a compact, passively cooled, maintenance-free laser with a typical output in the 100mW range. The power amplifier is a doped glass fibre, which is usually coiled in the laser source housing. This gives you a large amplification distance with a low construction volume. The power amplifier is provided with power by pump diodes, i.e. optically. The big benefit in comparison to “classical” Nd:YAG / Nd:YVO lasers is that each pump diode is separated spatially and mounted to its own heat sink. This alleviates the problem of high volumes of waste heat in small volumes. The light from the pump diodes is conducted to the power amplifier using fibre optic cables.