WAVELENGTH CONVERSION ELEMENT

摘要

A wavelength conversion element (20) is characterized in that it comprises a non-linear optical crystal having a periodic polarization-reversed structure where positive and negative polarities alternate with a period (d) represented by expression (1), and outputs a light having a frequency 2? with respect to the incident light having a frequency ? by using quasi phase matching, and that the non-linear optical crystal is a nitride single crystal such as AlN. d=m?/[2(n2?-n?)] (1) where m is the order of phase matching, ? is the wavelength of the incident light, n? is the refractive index of the nitride single crystal such as AlN with respect to a light having a frequency ?, and n2? is the refractive index of the nitride single crystal such as AlN with respect to light having a frequency 2?.