THE PRINCIPLE

The optical excitation in diode pumped Yb:YAG lasers is generated by high power, laser diode modules, assembled into stacks. After beam shaping, the pump light (wavelength of 940 nm) emitted by these laser diodes is reflected by a parabolic mirror onto the laser-active material, a thin disc of special Yb:YAG crystal. The pump light is reflected from the coated back side of the disc and strikes the parabolic mirror a second time, deflects onto a retro reflector, before returning to the parabolic mirror to be recoupled into the disc. This process repeats until after 16 passes through the disc the pump light is completely absorbed. A second coating on the back of the disc and an outcoupling mirror, situated in front of the parabolic reflector, set up the resonator. The emerging laser light of very high beam quality is coupled by suitable optics into a fiber optic with a diameter of 150 µm or 300 µm. The laser output can be delivered down several fiber optics by using fast beam switching, so that a single source can be utilized efficiently.