Patent ID: 7848011

Claim:
A wavelength converting element that receives a fundamental wave of light of a wavelength lambda to output a second harmonic of light of a wavelength lambda/2, comprising: a crystal including at least one element selected from the group consisting of Y, La, Ce, Gd, Sc, Ho and Lu as an additive to absorb a third harmonic of light of a wavelength lambda/3 by sum frequency generation of the fundamental wave and the second harmonic, wherein said crystal consists essentially of any one of lithium niobate LiNbO 3 and lithium tantalate LiTaO 3 , wherein said additive is configured to prevent the second harmonic of light from interacting with the third harmonic of light by absorbing the third harmonic of light whereby an output saturation of the second harmonic of light is suppressed, and wherein the second harmonic of light has a power density of 50 kW/cm 2 or more.