Acta Optica Sinica, Volume. 43, Issue 19, 1913001(2023)

Low-Loss Apodized Grating Couplers Based on Lithium Niobate on Insulator

Yakang Liu, Xuan She*, Hongshuo Liu, Fei Huang, Kan Chen, Ran Bi, Lei Wang, and Xiaowu Shu
Author Affiliations
  • College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, Zhejiang , China
  • show less
    Figures & Tables(8)
    Cross-sectional schematic of uniform grating
    Grating couplers in different design schemes. (a) Partial schematic of linearly chirped grating with linearly changed fill-factor and fixed period; (b) partial schematic of proposed linearly apodized grating; (c) cross-sectional schematic of proposed linearly apodized grating
    Variation trends of effective index ne and coupling efficiency. (a) Effective index ne as a function of etching depth e in TE0 mode at 1550 nm; (b) 2D contour map of coupling efficiency at 1550 nm as a function of e and R
    Effect comparison of uniform grating, apodized grating in Ref. [18], and apodized grating in this work. (a) Normalized field distributions at 1550 nm along x direction; (b) upward transmission; (c) coupling efficiency
    Grating couplers with etching inclination angle. (a) Cross-sectional schematic of waveguide with etching inclination angle; (b) cross-sectional schematic of apodized grating with etching inclination angle
    Diffraction electric field distribution and coupling efficiency. (a) Diffraction electric field distribution of apodized grating for TE polarization; (b) diffraction electric field distribution of apodized grating with etching inclination angle for TE polarization; (c) coupling efficiency of apodized grating with etching inclination angle as a function of Ffb,1
    • Table 1. Optimal periods and fill-factorsobtained from optimization of apodized grating in 500 nm Z-cut LNOI platform, when e=340 nm and R=0.035 μm-1

      View table

      Table 1. Optimal periods and fill-factorsobtained from optimization of apodized grating in 500 nm Z-cut LNOI platform, when e=340 nm and R=0.035 μm-1

      NumberPeriod /nmFill-factorNumberPeriod /nmFill-factorNumberPeriod /nmFill-factor
      18580.92089100.675159260.605
      28650.88599180.640169260.605
      38720.850109260.605179260.605
      48790.815119260.605189260.605
      58870.780129260.605199260.605
      68940.745139260.605209260.605
      79020.710149260.605
    • Table 2. Coupling efficiency comparison of demonstrated LNOI grating couplers in recent years

      View table

      Table 2. Coupling efficiency comparison of demonstrated LNOI grating couplers in recent years

      StructureReflectorAngle /(°)Simulated efficiency /dBReference
      UniformYes82 dB21
      ChirpedYes1.688.7%(0.52 dB)19
      UniformYes00.71 dB22
      ChirpedNo2.666.6%(1.8 dB)20
      ApodizedNo81.8 dB18
      UniformNo850.4%(3 dB)25
      UniformNo86.6 dB26
      UniformNo122.7 dB23
      UniformNo85 dB27
      ApodizedNo881.3%(0.90 dB)This work
    Tools

    Get Citation

    Copy Citation Text

    Yakang Liu, Xuan She, Hongshuo Liu, Fei Huang, Kan Chen, Ran Bi, Lei Wang, Xiaowu Shu. Low-Loss Apodized Grating Couplers Based on Lithium Niobate on Insulator[J]. Acta Optica Sinica, 2023, 43(19): 1913001

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category: Integrated Optics

    Received: Mar. 8, 2023

    Accepted: Apr. 23, 2023

    Published Online: Oct. 23, 2023

    The Author Email: Xuan She (0013808@zju.edu.cn)

    DOI:10.3788/AOS230650

    Topics