; National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China and Physics Department, Nanjing University, Nanjing 210093, China
The authors reported a type of second-harmonic generation in a hexagonally poled LiTaO3 waveguide. The emerged second-harmonic waves exhibited a hexagonal pattern when projected on a screen behind the waveguide. This frequency conversion process was realized by guided-to-radiated mode interaction. Phase matching for this process was automatically achieved by a quasi-phase-matched Čerenkov configuration.