Optical wavelength-converting device for guided-wave second-harmonic generation in Cerenkov radiation mode

摘要

An optical wavelength-converting device for generating the second-harmonic wave through Cerenkov radiation has a substrate (12) made from nonlinear optical crystal which acts as a cladding layer. Formed on the top surface of the substrate is a long, narrow waveguide layer (16), whose refractive index is larger than that of the substrate. In the substrate (12), multi-layered domain-inverted sections (14a, 14b, 14c) are formed. With this arrangement, the nonlinear optical coefficient is locally changed, there by compensating for phase mismatching between the fundamental wave and the second-harmonic wave in the direction perpendicular to the substrate's surface. This compensation helps improve the efficiency in converting the laser input light (18) of the fundamental wave into the second-harmonic wave (20).