Details

Autor(en) / Beteiligte

• Liu, Yuheng
• Xia, Lipeng
• Li, Ting
• Sun, Yuhan
• Zhou, Peiji
• Shen, Li
• Zou, Yi

Titel

High-efficiency mid-infrared on-chip silicon grating couplers for perfectly vertical coupling

Ist Teil von

• Optics letters, 2023-01, Vol.48 (2), p.239-242

Ort / Verlag

United States: Optical Society of America

Erscheinungsjahr

2023

Quelle

OSA Publishing

Beschreibungen/Notizen

• We present, to our knowledge, the first experimental demonstration of two on-chip gratings for perfectly vertical coupling at wavelengths of 3350 nm and 3550 nm, respectively. An anti-backreflection unit containing a fully etched trench and a subwavelength pillar is introduced in each grating period, together with a binary-approximated blazed unit, interleaving fully and shallow-etched slots in 500-nm thick silicon film. Both gratings show a strong ability to eliminate backreflection and provide predicted directionality of around 80%. The physical theoretical analysis is applied during further apodization for mitigating the computation of the optimization algorithm, improving the efficiency and optimization reliability, and increasing the fabrication robustness. The measured coupling efficiencies (CEs) of the gratings are -5.58 dB and -4.34 dB at wavelengths of 3350 nm and 3550 nm, with a 3-dB bandwidth of at least 87 nm and 210 nm, respectively.