QPM Wavelength Converter Using Direct-Bonded Ridge Waveguide With Integrated MMI Multiplexer

We fabricated a wavelength-division multiplexer for 0.78- and 1.56-μm light using multimode interference (MMI) in a direct-bonded LiNbO
₃
ridge waveguide. We obtained a low excess insertion loss of 1.0 and 0.5 dB for 0.78- and 1.56-μm light, respectively. We integrated a quasi-phase-matched (QPM) wavelength converter with an MMI multiplexer on one chip for the first time. We successfully demonstrated high-quality wavelength conversion based on difference-frequency generation with a parametric gain.