There is a problem that some lasers go not cut or engrave on different materials, for example, metals, glass, plexiglass.
An explanation is very simple – different materials absorb and reflect different wavelength, therefore, more power is absorbed – easy cutting or engraving will be. More power is being reflected – less power will achieve the surface.
For example, nickel and copper almost do not absorb 445 nm wavelength while nickel coin and copper do absorb much better 808 nm.
Based on researchgate data you may see that aluminum absorbs wavelength shorter than 100 nm and almost does not of other wavelength, has a small spike somewhere 850-900 nm.
For example gold and silver are kind of sensitive to the wavelength 300-500 nm.
As you may see steel and pure iron are sensitive to wavelength more than 1050 nm. that is why most fiber lasers for metal cutting use 1064 / 1080 nm wavelength.
According to keyence research, you may see that all metals except the aluminum have downslope after 450 nm.
Why it is impossible to engrave or cut with lasers of wavelength more than 300 nm
As you can see on this chart almost all types of glass are transmitting all wavelength longer than 300 nm
Glass cutting is possible with the laser with a wavelength of more than 4.4uM (4400 nm)
The regular glass absorbs wavelength longer than 4000 nm (4 uM) which is far infrared, that is why laser cutting of glass and acrylic can be don on Co2 lasers with a wavelength of 10.6 uM.