The most popular way of achieving power scalability is the “MOPA” (Master Oscillator Power Amplifier) approach. The “MO” produces a highly coherent beam, and an optical “A” is used to increase the power of the beam while preserving its main properties. The “MO” has no need to be powerful, and has no need to operate at high efficiency because the efficiency is determined mainly by the “PA”. The combination of several laser amplifiers seeded by a common “MO” is essential concept of the High Power Laser Energy Research Facility. This is Mopa fiber laser marking machine.