使用磁控溅射制备了掺铒氧化铝薄膜, 对薄膜进行了退火处理, 测量薄膜的折射率和X射线衍射图谱, 发现薄膜在600 ℃的退火温度下呈非晶态, 在1.5 μm处的折射率为1.67左右。模拟模场分布, 获得光与掺铒层之间相互作用最大的波导结构参数, 并进一步优化制备条件, 实现侧壁光滑的低损耗掺铒氧化铝脊型波导。在1.31 μm的波长下, 2 μm宽度的氧化铝脊型波导的损耗为1.6 dB/cm, 和使用超快激光灼烧的方法所制备出的损耗为3.8 dB/cm氧化铝脊型波导相比, 损耗大为降低。结果表明, 掺铒氧化铝波导在平面集成波导放大器应用方面极具潜力。

Er-doped Al2O3 films were prepared using the magnetron-sputtering method, and the films were thermal-annealed. We measured the refractive index and X-ray diffraction patterns of the films, and it was found that the films were amorphous at annealing temperatures up to 600 ℃, and the refractive index was 1.67 at 1.5 μm. We investigated the correlation between the photoluminescence intensity and Er-doping content, and the optimal deposition conditions for the films were obtained. We simulated the mode field distribution and achieved the structural parameter of the waveguide where the interaction between light and Er-doped layer is the maximum. We further optimized the fabrication conditions and achieved Er-doped Al2O3 waveguide with smooth side wall and low optical loss. The 2 μm-wide waveguide has an optical loss at 1.6 dB/cm at 1.31 μm. Compared with the alumina ridge waveguide with a loss of 3.8 dB/cm prepared by the ultrafast laser ablation method, the loss is greatly reduced, showing the potentials of the Er-doped Al2O3 waveguide used as on-chip optical amplifiers.