Wavelength conversion element, laser light source, two-dimensional image display and laser processing system

A wavelength conversion element, comprising a substrate including a nonlinear optical single crystal having a periodically poled structure, wherein:

• the substrate is made of lithium niobate;
• the visible light transmittance of the substrate is 85% or higher when ultraviolet light is irradiated to the substrate;
• and
• the wavelength conversion element outputs laser light having an average output of 1 W or more by shortening the wavelength of laser light having a wavelength of 640 nm to 2000 nm.

A wavelength conversion element, comprising a substrate including a nonlinear optical single crystal having a periodically poled structure, wherein:

• the substrate is made of lithium tantalate;
• the visible light transmittance of the substrate is 85% or higher when ultraviolet light is irradiated to the substrate;
• and
• the wavelength conversion element outputs laser light having an average output of 1 W or more by shortening the wavelength of laser light having a wavelength of 640 nm to 2000 nm.