Hello,
I intend to construct a system utilizing a high-power fiber laser source within the 1-10 kW range. I am mainly interested in continuous-wave (CW) multimode lasers (1 micron) with an output power ranging from 1-10 kW. As I am relatively new to the field of lasers and optics, I am seeking guidance on the key parameters to take into account when sourcing optical components such as mirrors, lenses, beamsplitters, and prisms.
What are the main distinctions between high-power and low-power optics? Do you have any recommended references for in-depth knowledge on this topic?
Also, what are the standard practices for implementing cooling of optical components?
Hello Vytka,
Omeda got you covered with coatings 
Your question is a bit too general, but I will try to give you some insight.
I guess it’s really the laser induced damage threshold what matters and the optics should not be glued as the glue will soften when it heats up. For high power you can easily use cooled copper mirrors. Look at this piece. TRUMPF usually goes very industrial on every high power component: high thermal conductivity metals (mostly diamond turned oxygen free copper) and a lot of thermal mass.
Make sure you consider that the gaussian peak power is double the average when calculating power density on the mirrors. Over 3kW there won’t be any single mode choice so with flat top it’s not double.
The beam delivery optics has different bend radii which must not be exceeded. Otherwise you risk burning down the thing - there are short term and long term bend radii limits for both mechanical and optical damage. Backreflection could be an issue too while cutting copper. A 3kW laser can take only a couple or seconds if there is a lot coming back, but most lasers will turn-off when it’s getting bad anyway.
Thermal lensing shift of the focusing optics might be an issue so when setting up the distance to the workpiece cold it should not be in focus. Be aware that flat optics will behave as a thermal lens too. The surface of the optics can also deform under such high power, make sure you have a large beam diameter.
While measuring power make sure you have again a large beam on the water cooled power meter, the damage threshold of those coatings is also limited.
I’m not sure if anyone is using prisms with such high power. What could it be used for? If there is a use case, just make sure you don’t use any cemented doublets or splitters, those will get quickly damaged. If you have to, go for plate beam splitters or optically contacted stuff.
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