A novel geometry parameterization, optimization and simulation of realistic AL2O3-based optical waveguide Y-branches

Integrated optics are expected to exhibit a growth rate similar to that exhibited by integrated electronics several decades ago. However, in order to maintain its growth and to produce highly functional, densely integrated optical devices, advanced design methods should be developed. In this thesis, we showcased how to merge an optimization technique with a powerful electromagnetic solver to form a design tool which is capable of finding optimal designs while fulfilling some constraints. Namely, we used Particle Swarm Optimization algorithm combined with Finite-Difference Time-Domain electromagnetic solver to find the optimal geometry of a single-mode optical waveguide Y-branch while ensuring design fabricability within a 1 μm-resolution standard lithography. The proposed design has a mean total insertion loss of 0.45 dB over wavelengths ranging from 1450 to 1580 nm with a footprint of around 40 by 10 μm. Novel aspects of our work include the introduction of a new design parameterization and the usage of a weakly guiding material system, namely Al2O3 over SiO2 which is more challenging than strongly guiding material systems. Finally, all simulations presented in this thesis are based on a realistic waveguide geometry which proved to be extremely important for simulations to reflect reality. In this thesis, amorphous Al2O3 grown using Atomic Layer Deposition technique was chosen because it is very promising for the realization of active and passive integrated optical components.