Articles you may be interested inContinuous wave second-harmonic generation using domain-disordered quasi-phase matching waveguides Appl. Phys. Lett. 94, 151107 (2009); 10.1063/1.3119629Broadband quasi-phase-matched second-harmonic generation in a nonlinear photonic crystal Quasi-phase matched second-harmonic generation in an Al x Ga 1−x As asymmetric quantum-well waveguide using ion-implantation-enhanced intermixing Phase-matched optical second-harmonic generation in GaN and AlN slab waveguides

Channel waveguides were formed on fused silica substrate by Ge-ion implantation with lithographically defined channels. Thermal poling was performed to form second order optical nonlinearity (SON) in the waveguides. Periodical photo masks were designed and fabricated on a mask glass. Periodical erasure of the SON in the channel waveguides by 266 nm UV light with the photo mask on the fused silica substrate produced periodical SON distribution in the waveguides. First order quasi-phase-matching second-harmonic generation from 1064 nm to 532 nm was demonstrated in the channel waveguides.

Blues pulses 300 fs long have been generated from 150 fs infrared pulses by compressing second harmonic radiated in the Cerenkov geometry. Mode-locked Ti:sapphire pulses were prism coupled into a 1-cm long proton-exchanged MgO:LiNbO3 planar waveguide. The 2 ps Cerenkov output, chirped due to group velocity mismatch, was then compressed by a diffraction grating down to 300 fs. The use of mode-locked pulses results in a conversion efficiency of 1000%/W/cm, three orders of magnitude higher than by cw doubling in the same geometry. The Cerenkov geometry ensures that all wavelengths can be phase matched over long crystal length, so that even low power lasers can be efficiently doubled. The dispersion element ensures that the chirped output can be compressed into the femtosecond regime. This concept can be extended to femtosecond pulses in any two-photon process in any waveguide material and any mode-locked source.