Analysis of optical losses of GaAs waveguides for single-photon sources considering realistic waveguide roughness

Photonic integrated circuits are a promising technology for quantum applications, which are known to impose stringent requirements on the performance characteristics of utilized components. Besides achieving high efficiency of active photonic components, low optical losses of waveguiding and coupling structures are of the same importance. In this contribution we focus on the analysis of optical losses related to waveguiding of single photons generated by InAs quantum dots in GaAs strip waveguides. We perform a simulation study of the effects of GaAs waveguide nanoscale surface roughness on the waveguide propagation losses. This study is also supported by experimental data on line edge roughness and surface roughness of fabricated GaAs waveguides determined from SEM and AFM analyses. The roughness applied in simulation is based on the statistical properties of this data. The results of our analysis strengthen our understanding of scattering losses and their individual contributing factors. We also conclude that for the investigated GaAs waveguides the contribution of scattering on the waveguide top surface roughness to the propagation losses is very small compared to the contribution of sidewall scattering.