Quaternary III-V semiconductor compounds for integrated nonlinear optics

In this study, we propose several designs for integrated waveguides based on quaternary III-V semiconductor compounds InGaAsP (on InP substrate) and AlGaAsSb (on GaSb substrate), and report on their fabrication and optical characterization. III-V semiconductor compounds tend to exhibit strong nonlinearities; these typically come along with undesirable effects such as nonlinear absorption. In quaternary III-V compounds, one has a good control over this characteristic. For instance, by shifting the band-gap wavelength through adjusting the material composition, one can change the range of wavelengths that can experience two-photon absorption. Therefore, it would be possible to minimize the losses due to nonlinear absorption [1]. Based on the possible band-gap wavelength and refractive index ranges that can be achieved in these two compounds, one can expect that both InGaAsP and AlGaAsSb waveguides can be suitable for wide-range wavelength conversion. InGaAsP waveguides can, for example, be co-integrated with InGaAsP laser sources to extend their operation ranges to longer wavelengths (2 μm and beyond). The properties of AlGaAsSb, on the other hand, allow passive waveguide devices operating in the Telecom C-band.