We report on the fabrication and optical characterization of erbium-ytterbium co-doped aluminum oxide (Al₂O₃:Er³⁺:Yb³⁺) waveguides using low-cost, low-temperature deposition and etching steps. We deposited Al₂O₃:Er³⁺:Yb³⁺ films using reactive co-sputtering, with Er³⁺ and Yb³⁺ ion concentrations ranging from 1.4–1.6 × 10²⁰ and 0.9–2.1 × 10²⁰ ions/cm³, respectively. We etched ridge waveguides in 85% pure phosphoric acid at 60°C, allowing for structures with minimal polarization sensitivity and acceptable bend radius suitable for optical amplifiers and avoiding alternative etching chemistries which use hazardous gases. Scanning-electron-microscopy (SEM) and profilometry were used to assess the etch depth, sidewall roughness, and facet profile of the waveguides. The Al₂O₃:Er³⁺:Yb³⁺ films exhibit a background loss as low as 0.2 ± 0.1 dB/cm and the waveguide loss after structuring is determined to be 0.5 ± 0.3 dB/cm at 1640 nm. Internal net gain of 4.3 ± 0.9 dB is demonstrated at 1533 nm for a 3.0 cm long waveguide when pumped at 970 nm. The material system is promising moving forward for compact Er-Yb co-doped waveguide amplifiers and lasers on a low-cost silicon wafer-scale platform.

中文翻译：

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通过反应共溅射和湿法化学刻蚀制造的co--共掺杂氧化铝波导放大器

我们报告了使用低成本，低温沉积和蚀刻步骤的co- co共掺杂氧化铝（Al ₂ O ₃：Er ³⁺：Yb ³⁺）波导的制造和光学特性。我们使用反应性共溅射沉积Al ₂ O ₃：Er ³⁺：Yb ³⁺膜，其中Er ³⁺和Yb ^3+的离子浓度范围为1.4–1.6×10 ²⁰和0.9–2.1×10 ²⁰离子/ cm ³， 分别。我们在60°C的温度下用85％的纯磷酸蚀刻了脊形波导，从而使结构具有最低的偏振敏感度和可接受的弯曲半径，适用于光放大器，并避免了使用有害气体的替代蚀刻方法。扫描电子显微镜（SEM）和轮廓仪用于评估波导的蚀刻深度，侧壁粗糙度和刻面轮廓。Al ₂ O ₃：Er ³⁺：Yb ³⁺薄膜表现出低至0.2±0.1 dB / cm的背景损耗，结构化后的波导损耗在1640 nm处确定为0.5±0.3 dB / cm。当在970 nm泵浦时，对于3.0 cm长的波导，在1533 nm处的内部净增益为4.3±0.9 dB。该材料系统有望在低成本的硅晶圆级平台上用于紧凑型Er-Yb共掺杂波导放大器和激光器。