Highly efficient second-harmonic generation in direct-bonded MgO:LiNbO3 pure crystal waveguide

Quasi-phase-matched second-harmonic generation in a pure crystal waveguide (PCW) is presented. A direct-bonded ridge structure with airgap boundary achieved the PCW in 3.2 mum periodically poled MgO:LiNbO3. In a single-pass configuration, CW 40 mW of blue light was generated with power conversion efficiency of 59%.