Limiting efficiencies of second-harmonic generation and cascaded χ(2) processes in quadratically nonlinear photonic nanowires

Quadratically nonlinear waveguides with subwavelength core dimensions are shown to provide limiting efficiencies of second-harmonic generation and three-wave mixing, as well as cascaded χ(2) nonlinear-optical interactions. Small-core waveguides made of high-χ(2) materials, such as gallium arsenide and indium phosphide, are shown to allow anomalous dispersion to be achieved within the range of wavelengths from 1.3 to 2.0 μm, with the wavelength of zero group-velocity dispersion controlled by the size of the waveguide core.