Optical gain evaluation on rare-earth doped Yttria-stabilized Zirconia for hybrid integration on silicon photonics platforms

New optical materials for hybrid photonic integration on silicon platform have become a hot research topic aiming at providing additional functionalities. In this regard, functional oxides are a very interesting class of materials due to their singular properties. Material engineering is commonly employed to tune and manipulate such properties at will, thus being functional oxides often used to build active reconfigurable elements in complex systems. Transparent oxides with moderate refractive indexes are targeted for hybrid integration due to the rewarding benefits envisioned. Yttria-Stabilized Zirconia (YSZ) is a chemically stable oxide(1) with a transparency range that spans from the visible to the mid-IR2, with a refractive index around 2.1, which makes this functional oxide interesting for the development of low-loss waveguides when grown over a low contrast substrate. While these optical properties are very interesting for various applications, including on-chip optical communications and sensing, YSZ has remained almost unexplored in photonics up to now. Nevertheless, this complex functional oxide shows interesting optical properties such as low-moderate propagation losses of 2 dB/cm at telecom wavelengths(3). In our work, we explore the deposition of erbium doped YSZ by pulsed layer deposition (PLD) on a multilayer approach providing outstanding luminescence in correspondence with C-band of telecommunication window (lambda = 1530 nm) and in the visible range by means of up-conversion processes. The optical properties of active layers of Er-doped YSZ grown on waveguides in different platforms and under resonant pumping will be discussed in this paper, as well as their propagation losses. Based on the preliminary study of these active hybrid systems, we envision light amplification functionalities based on rare-earth doped functional oxides.