Reliable Low-Cost Fabrication of Low-Loss $\hbox{Al}_{2}\hbox{O} _{3}{:}\hbox{Er}^{3+}$ Waveguides with 5.4-dB Optical Gain

A reliable and reproducible deposition process for the fabrication of $\hbox{Al}_{2}\hbox{O}_{3}$ waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ${\sim 5} \hbox{nm}/\min$ deposition rate and exhibit excellent thickness uniformity within 1% over 50×50 $\hbox{mm}^{2}$ area and no detectable $\hbox{OH}^{-}$ incorporation. For applications of the $\hbox{Al}_{2}\hbox{O}_{3}$ films in compact, integrated …