### Nonlinear Optics in III-V Quaternary Semiconductor Waveguides

##### Description
 Title: Nonlinear Optics in III-V Quaternary Semiconductor Waveguides Authors: Saeidi, Shayan Date: 2018 Abstract: The fundamental limits of electronic systems in communication networks motivated scholars to think of an alternative approach to overcome problems such as demand for wider bandwidths and heat dissipation. All-optical signal processing is demonstrated as a potential solution. A major improvement in cost and speed of networking systems is expected through replacing microelectronics by photonic chips. However, the variety of operations essential to perform all-optical signal processing cannot be handled by a single material platform yet. Several III-V semiconductors, such as AlGaAs, have demonstrated potentials for photonic integration; nevertheless, there is still lack of data in literature on nonlinear optical properties of these materials. In this thesis, we extend the quest to evaluate more candidates from this class of semiconductors. Moreover, we are aiming for demonstrating the potentials of various III-V compounds for nonlinear photonics on-a-chip. In this thesis, we propose several optical waveguide designs based on quaternary III-V semiconductors AlGaAsSb and InGaAsP. We present modal analysis for waveguide designs and show that effective mode area much less than 1 $\mu m^{2}$ can be obtained. We also report specific waveguide designs that display zero-dispersion points at the specific wavelength ranges of interest. The designed waveguides are thus expected to demonstrate efficient nonlinear optical interactions. Next step is the fabrication of these devices with the goal to experimentally assess their nonlinear optical performance. The fabrication process of InGaAsP/InP strip-loaded waveguide is briefly reviewed. Following that, we report on the first, to the best of our knowledge, demonstration of third-order nonlinear optical interactions in InGaAsP/InP strip-loaded waveguides. We have performed self-phase modulation, nonlinear absorption measurements, and four-wave mixing experiments at the telecom wavelength range. The nonlinear phase shift up to 2.5 $\pi$ has been observed. Following that, we use Monte-Carlo method for design optimization and tolerance analysis of a multi-step lateral taper Spot-Size Converter in indium phosphide. An exemplary four-step lateral taper design featuring 0.35 dB coupling loss at optimal alignment of a standard single-mode fiber, $>$7 $\mu m$ 1-dB displacement tolerance in any direction of in a facet plane, and a great stability against manufacturing variances demonstrated. URL: http://hdl.handle.net/10393/37300http://dx.doi.org/10.20381/ruor-21572 Collection Thèses, 2011 - // Theses, 2011 -