Loss-less Wavelength Converter with Ridge-Type Annealed Proton-Exchanged Periodically Poled MgO-Doped Congruent LiNbO3 Waveguide

A loss-less wavelength converter based on a periodically poled MgO-doped congruent LiNbO3 (PPMgCLN) waveguide was demonstrated. The waveguide was simply fabricated by applying annealed proton exchange (APE) to a ridge structure. To optimize the APE condition, the proton concentration profiles and the diffusion coefficients were evaluated by secondary ion mass spectroscopy. We also optimized the mode field profiles within the ridge waveguide to improve the overlapping among different wavelengths. The parametric gain of the cascaded difference frequency generation was 2.5 dB. Since the insertion loss of the wavelength conversion module was 2.2 dB, a loss-less PPMgCLN wavelength converter was successfully demonstrated. (C) 2012 The Japan Society of Applied Physics