• Photonics Research
  • Vol. 11, Issue 2, 189 (2023)
Rongxiang Guo1、2, Shujiao Zhang1、2, Haoran Gao1、2, Ganapathy Senthil Murugan3, Tiegen Liu1、2, and Zhenzhou Cheng1、2、4、5、*
Author Affiliations
  • 1School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
  • 2Key Laboratory of Optoelectronics Information Technology, Ministry of Education, Tianjin 300072, China
  • 3Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK
  • 4Georgia Tech-Shenzhen Institute, Tianjin University, Shenzhen 518055, China
  • 5Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
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    DOI: 10.1364/PRJ.474199 Cite this Article Set citation alerts
    Rongxiang Guo, Shujiao Zhang, Haoran Gao, Ganapathy Senthil Murugan, Tiegen Liu, Zhenzhou Cheng. Blazed subwavelength grating coupler[J]. Photonics Research, 2023, 11(2): 189 Copy Citation Text show less

    Abstract

    Short-wavelength mid-infrared (2–2.5 μm wave band) silicon photonics has been a growing area to boost the applications of integrated optoelectronics in free-space optical communications, laser ranging, and biochemical sensing. In this spectral region, multi-project wafer foundry services developed for the telecommunication band are easily adaptable with the low intrinsic optical absorption from silicon and silicon dioxide materials. However, light coupling techniques at 2–2.5 μm wavelengths, namely, grating couplers, still suffer from low efficiencies, mainly due to the moderated directionality and poor diffraction-field tailoring capability. Here, we demonstrate a foundry-processed blazed subwavelength coupler for high-efficiency, wide-bandwidth, and large-tolerance light coupling. We subtly design multi-step-etched hybrid subwavelength grating structures to significantly improve directionality, as well as an apodized structure to tailor the coupling strength for improving the optical mode overlap and backreflection. Experimental results show that the grating coupler has a recorded coupling efficiency of -4.53 dB at a wavelength of 2336 nm with a 3-dB bandwidth of 107 nm. The study opens an avenue to developing state-of-the-art light coupling techniques for short-wavelength mid-infrared silicon photonics.
    α(x)=0.5G2(x)10xG2(τ)dτ,(A1)

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    Rongxiang Guo, Shujiao Zhang, Haoran Gao, Ganapathy Senthil Murugan, Tiegen Liu, Zhenzhou Cheng. Blazed subwavelength grating coupler[J]. Photonics Research, 2023, 11(2): 189
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