The most popular way of achieving power scalability is the “MOPA” (Master Oscillator Power Amplifier) approach. The master oscillator produces a highly coherent beam, and an optical amplifier is used to increase the power of the beam while preserving its main properties. The master oscillator has no need to be powerful, and has no need to operate at high efficiency because the efficiency is determined mainly by the power amplifier. The combination of several laser amplifiers seeded by a common master oscillator is essential concept of the High Power Laser Energy Research Facility. A MOPA laser source is a great way to expand your marking capabilities and improve the quality of your marking results on certain plastics and metals. With a conventional fiber laser, markings on certain metals and plastics (especially if they are dark in color) can be less homogeneous and rich in contrast. The MOPA laser source is a great solution in these cases because it allows you to select pulse durations, which translates into a wider range of laser parameters and more marking options. As a result, the MOPA can mark plastics with higher-contrast and more legible results, mark (anodized) aluminum in black, and create reproducible colors on steel.
Selectable pulse durations not only improve marking results on certain metals and plastics, but also provide more marking capabilities. With the MOPA laser, the pulse durations can be set to predefined values between 2 ~ 200 ns. Because it offers such a wide range of pulse durations, the MOPA is one of the most flexible lasers on the market. It can simulate the properties of conventional fiber lasers such as Nd:YAG or Nd:YVO4. You can also produce qualitatively equivalent markings with the MOPA laser partially faster than with the conventional fiber laser.
Using short pulses and lower pulse energy heat the material less, and the area of the heat affected zone is reduced. This results in more advantages and possibilities for laser marking metals and plastics:
- Less burning/melting in the edge area of metal engravings
- Less heat development during annealing markings on metal, which leads to a better corrosion behavior
- Controlled melting of plastics
- Less foaming with plastics
- More homogeneous and sometimes higher-contrast markings on some plastics
The advantages of the conventional fiber laser sources remain unchanged:
- long service life