Understanding and mitigating optical loss is critical to the development of
high-performance photonic integrated circuits (PICs). Especially in high
refractive index contrast compound semiconductor (III-V) PICs, surface
absorption and scattering can be a significant loss mechanism, and needs to be
suppressed. Here, we quantify the optical propagation loss due to surface state
absorption in a suspended GaAs photonic integrated circuits (PIC) platform,
probe its origins using X-ray photoemission spectroscopy (XPS) and
spectroscopic ellipsometry (SE), and show that it can be mitigated by surface
passivation using alumina (Al2​O3​). We also explore potential routes
towards achieving passive device performance comparable to state-of-the-art
silicon PICsComment: 8 pages, 8 figures, Comments welcome !!! v2: fixed typo in equation
1, minor edits in tex