We propose a novel high-efficiency, low-reflection, and fabrication-tolerant perfectly vertical grating coupler (PVGC) with a minimum feature size $>200\mathrm{nm}$ to allow for fabrication using 193 nm deep-ultraviolet lithography. The structural parameters of PVGC were optimized by a genetic optimization algorithm. Simulations predicted the coupling efficiency to be $-2.0\mathrm{dB}$ (63.0%) and the back reflections to be less than $-20\mathrm{dB}$ in the wavelength range of 1532–1576 nm. The design was fabricated in a multi-project wafer run for silicon photonics, and a coupling efficiency of $-2.7\mathrm{dB}$ (53.7%) with a 1 dB bandwidth of 33 nm is experimentally demonstrated. The measured back reflection is less than $-16\mathrm{dB}$ over the C-band. The PVGC occupies a compact footprint of $30\mathrm{\mu m}\times 24\mathrm{\mu m}$ and can be interfaced with the multi-core fibers for future space-division-multiplexing networks.

中文翻译：

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高效的垂直垂直光栅耦合器，适用于采用193 nm DUV光刻技术制造的多芯光纤

我们提出了一种具有最小特征尺寸的新型高效，低反射且可制造的完美垂直光栅耦合器（PVGC） $>200\mathrm{纳米}$以允许使用193 nm深紫外光刻技术进行制造。通过遗传优化算法对PVGC的结构参数进行了优化。仿真预测耦合效率为$-2.0\mathrm{D\; b}$ （63.0％）并且背反射小于 $-20\mathrm{D\; b}$在1532-1576 nm的波长范围内。该设计是在用于硅光子的多项目晶圆中制造的，耦合效率为$-2.7\mathrm{D\; b}$实验证明1dB带宽为33 nm（53.7％）。测得的背反射小于$-16\mathrm{D\; b}$在C波段上。PVGC占用的空间很小$30\mathrm{微米}\times 24\mathrm{微米}$ 并且可以与多芯光纤接口，以用于未来的空分复用网络。