High-gain Suspended Silicon Nitride Waveguide Amplifiers En-abled by Double-sided $\text{Er}^{3+}:\mathrm{A}1_{2}\mathrm{O}_{3}$ Coating

We demonstrate a suspended$\mathrm{S}i_{3}N_{4}$erbium-doped waveguide amplifier (EDWA), achieving 22.29-dB net gain and 12.51-dBm on-chip output power. This is enabled by double-sided atomic layer deposition (ALD) of the$\mathrm{S}i_{3}N_{4}$core with$Er^{3+}: Al/_2\mathrm{O}_{3}$films, which sets a new benchmark for ALD-based EDWAs. ©2025 The Author(s)