Semiconductor Wavelength Converting Devices and Light Sources for Generating Infrared Rays

A wavelength converting device generating an idler light having a wavelength of 5 to 10 μm from a pump light, said wavelength of said idler light being longer than that of said pump light, said wavelength converting device comprising:

• a wavelength converting layer comprising a semiconductor non-linear optical crystal and having a thickness of 50 μm or smaller, said wavelength converting layer comprising at least one flat main face and a crystal orientation inversion structure wherein crystal orientation of said optical crystal is inverted at a predetermined period;
• a Peltier device controlling a temperature of said wavelength converting layer;
• and
• a clad portion joined with said flat main face of said wavelength converting layer and provided between said wavelength converting layer and said Peltier device;
• wherein said pump light, said idler light and said signal light satisfies a phase matching condition of the following formula (1), in the conditions that “np” represents a refractive index of said wavelength converting layer with respect to said pump light, “λp” represents a wavelength of said pump light, “ns” represents a refractive index of said wavelength converting layer with respect to said signal light, “λs” represents a wavelength of said signal light, “ni” represents a refractive index of said wavelength converting layer with respect to said idler light, “λi” represents a wavelength of said idler light, and “λ” represents a period of inversion of said crystal orientation.
• (n p/λp)=(n s/λs)+(n i/λi)+(1/Λ) (1)