Determination of the optical damage threshold of Rb-activated KTP waveguides

The dependence of the output power P_out, on the incident power P_in reaching the end of a waveguide was investigated for a channel waveguide made of Rb-activated potassium titanyl phosphate (KTP) аt λ = 514 μm. This dependence was linear in the range P_out = 0–450 mW. When the power density at the entry to the waveguide reached 10 MW/cm², optical damage to the crystal was observed in the form of a surface crater.