Li Qian, Tu Junjie, Tian Yang, Zhao Yanli
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
Sensors (Basel). 2020 Dec 2;20(23):6885. doi: 10.3390/s20236885.
Two types of configurations are theoretically proposed to achieve high responsivity polarization-insensitive waveguide Schottky photodetectors, i.e., a dual-layer structure for 1.55 µm and a single-layer structure for 2 µm wavelength band. Mode hybridization effects between quasi-TM modes and modes in plasmonic waveguides are first presented and further investigated under diverse metal types with different thicknesses in this work. By utilizing the mode hybridization effects between quasi-TE mode and mode, and also quasi-TM and mode in our proposed hybrid plasmonic waveguide, light absorption enhancement can be achieved under both TE and TM incidence within ultrathin and short metal stripes, thus resulting in a considerable responsivity for Si-based sub-bandgap photodetection. For 1.55 µm wavelength, the Au-6 nm-thick device can achieve absorptance of 99.6%/87.6% and responsivity of 138 mA·W/121.2 mA·W under TE/TM incidence. Meanwhile, the Au-5 nm-thick device can achieve absorptance of 98.4%/90.2% and responsivity of 89 mA·W/81.7 mA·W under TE/TM incidence in 2 µm wavelength band. The ultra-compact polarization-insensitive waveguide Schottky photodetectors may have promising applications in large scale all-Si photonic integrated circuits for high-speed optical communication.
理论上提出了两种配置以实现高响应度的偏振不敏感波导肖特基光电探测器，即用于1.55 µm的双层结构和用于2 µm波段的单层结构。本文首次介绍了等离子体波导中准横磁（TM）模式与其他模式之间的模式杂化效应，并在不同金属类型和不同厚度的情况下对其进行了进一步研究。通过利用我们提出的混合等离子体波导中准横电（TE）模式与其他模式以及准TM模式与其他模式之间的模式杂化效应，在超薄和短金属条带内，TE和TM入射情况下均可实现光吸收增强，从而为基于硅的子带隙光电探测带来可观的响应度。对于1.55 µm波长，6 nm厚的金器件在TE/TM入射情况下可实现99.6%/87.6%的吸收率和138 mA·W/121.2 mA·W的响应度。同时，在2 µm波段，5 nm厚的金器件在TE/TM入射情况下可实现98.4%/90.2%的吸收率和89 mA·W/81.7 mA·W的响应度。这种超紧凑的偏振不敏感波导肖特基光电探测器在用于高速光通信的大规模全硅光子集成电路中可能具有广阔的应用前景。
