Difference‐frequency generation in three‐dimensional linbo3 optical waveguide

Abstract

AbstractSince an optical waveguide can carry the light wave of high power density, very efficient nonlinear optical devices may be realized using the optical waveguide. Second harmonic generation in an optical waveguide has been reported. However, little has been known on difference‐frequency generation. This paper discusses generation of difference‐frequency signal in a three‐dimensional LiNbO3 optical waveguide which utilizes temperature variations of birefringence of LiNbO3 as a phase matching mechanism. From calculations of phase matching conditions, tuning characteristics and conversion efficiency of the difference‐frequency generation, it is found that the phase matching condition can be satisfied readily over a wide wavelength region and that the conversion efficiency in a 1‐cm long optical waveguide reaches a few percent with 100 mW pumping input. Further, using a three‐dimensional Ti‐diffused LiNbO3 waveguide, we generated difference‐frequency signals of a Rhodamine 6 G dye laser and a Nd:YAG laser. By changing the wavelength of the dye laser and the temperature of the optical waveguide, we generated difference‐frequency signals from 1.035 μm to 1.19 μm. At 1.035 μm wavelength, we generated 2.4 μW signals from the dye laser input of 70 mW and the Nd:YAG laser input of 1.7 mW.