Heterogeneous Integration of Doped Crystalline Zirconium Oxide for Photonic Applications

Hybrid integration of new materials will play a key role in the next photonics revolution, unlocking the development of advanced devices with outstanding performances and innovative functionalities. Functional oxides, thanks to the richness of their physical properties are promising candidates to build active reconfigurable elements in complex circuits. We review in this article our recent work regarding the hybrid integration of Yttria-Stabilized Zirconia (YSZ), a crystalline oxide with transparency from the visible to the mid-IR range with refractive index of about 2.15. YSZ is mostly studied for its high ionic conductivity, epitaxial growth on Si as buffer layer and its chemical stability but we demonstrated that it also holds a great potential in photonics for the development of low-loss waveguides (
$< $
2 dB/cm) and complex passive structures. Kerr refractive index of YSZ is in the same order of magnitude than well-known nonlinear materials such as silicon nitride. We explored the implementation of
$Er^{3+}$
ions as an active element providing outstanding luminescence in correspondence with C-band of telecommunications. The optical properties of active layers of Er-doped YSZ grown on waveguides in different platforms and under resonant pumping and its propagation losses, modal gain and signal enhancement will be discussed in this paper.