ABSTRACT
Second Harmonic Generation (SHG) devices based on waveguides achieve high conversion efficiencies because a large nonlinear coefficient is available and the waveguide can attain strong confinement with long interaction length. This chapter describes the SHG in waveguides and frequency doubling of laser diodes by using SHG devices. SHG devices in waveguides are attractive, especially for low power fundamental sources as, for example, laser diodes. Waveguide SHG is able to achieve high conversion efficiencies since the waveguide can attain strong confinement with a long interaction length. As fabrication techniques of waveguides in a nonlinear material, diffusion, ion-exchange, ion implantation, etc. have been reported. The waveguide fabrication technique by ion implantation is based on physical effects. Waveguide devices offer more flexibility in phase-matching, as they not only have larger allowances than bulk resonators, but also allow the generation of wavelengths not possible by the bulk approach.
