Guided-wave phase-matched second-harmonic generation in KTiOPO4 waveguide produced by swift heavy-ion irradiation

We report on the guided-wave second-harmonic generation in a KTiOPO4 nonlinear optical waveguide fabricated by a 17  MeV O5+ ion irradiation at a fluence of 1.5×1015  ions/cm2. The waveguide guides light along both TE and TM polarizations, which is suitable for phase-matching frequency doubling. Second harmonics of green light at a wavelength of 532 nm have been generated through the KTiOPO4 waveguide platform under an optical pump of fundamental wave at 1064 nm in both continuous-wave and pulsed regimes, reaching optical conversion efficiencies of 5.36%/W and 11.5%, respectively. The propagation losses have been determined to be ∼3.1 and ∼5.7  dB/cm for the TE and TM polarizations at a wavelength of 632.8 nm, respectively.