A new method for fabricating a high-quality buried-heterostructure optical waveguide using quantum well intermixing (QWI) has been demonstrated. By patterning a SiO2 thin film on top of a multiple quantum well (MQW) heterostructure, rapid thermal annealing (RTA) could induce laterally local QWI, resulting in a bandgap blueshift and a simultaneous decrease in the refractive index. Both lateral bandgap and index engineering could be attained along the MQW plane, which could be used for a buried-heterostructure optical waveguide. Two SiO2 strips with 3, 5 and 7 μm windows were fabricated for waveguide on a 1540 nm InGaAsP MQW sample. A 120 nm blueshift under the SiO2 area was observed, leading to the index contrast of 0.07. Far-field optical diffraction measurements were also performed to yield angles of 13.9°, 12.8° and 10.6°. A narrower window resulted in a narrower optical waveguide width and exhibited a larger diffraction angle, suggesting that QWI defined the buried optical waveguide. In addition, an electroabsorption modulator was also made by buried waveguide. A −10 dB low optical insertion loss and a 15 dB high extinction ratio in a 500 μm long waveguide were obtained, indicating that a buried heterostructure could be used for photonic devices and integration applications.

中文翻译：

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基于无杂质空位扩散量子阱混合的低损耗埋藏异质结构光波导

已经证明了一种使用量子阱混合 (QWI) 制造高质量埋入式异质结构光波导的新方法。通过在多量子阱 (MQW) 异质结构顶部图案化 SiO2 薄膜，快速热退火 (RTA) 可以引起横向局部 QWI，导致带隙蓝移和折射率同时降低。可以沿 MQW 平面实现横向带隙和折射率工程，这可用于埋入式异质结构光波导。在 1540 nm InGaAsP MQW 样品上制作了两个具有 3、5 和 7 μm 窗口的 SiO2 条用于波导。在 SiO2 区域下观察到 120 nm 蓝移，导致指数对比度为 0.07。还进行了远场光学衍射测量以产生 13.9°、12.8° 和 10.6° 的角度。较窄的窗口导致较窄的光波导宽度并表现出较大的衍射角，表明 QWI 定义了埋入式光波导。此外，还用埋入式波导制作了电吸收调制器。在 500 μm 长的波导中获得了 -10 dB 的低光插入损耗和 15 dB 的高消光比，表明埋入式异质结构可用于光子器件和集成应用。