Photonics Research, Volume. 13, Issue 2, 274(2025)

Polarization-insensitive silicon intensity modulator with a maximum speed of 224 Gb/s

Zanyun Zhang1, Beiju Huang2,3、*, Qixin Wang1, Zilong Chen4, Ke Li5,6, Kaixin Zhang3, Meixin Li1, Hao Jiang1, Jiaming Xing1, Tianjun Liu3, Xiaoqing Lv2,3, and Graham T. Reed6
Author Affiliations
  • 1Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, School of Electronic and Information Engineering, Tiangong University, Tianjin 300387, China
  • 2Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
  • 3Suzhou Institute of Microelectronics and Optoelectronics Integration, Suzhou 215213, China
  • 4Key Laboratory for Biomedical Engineering of Ministry of Education, Zhejiang University, Hangzhou 310027, China
  • 5Peng Cheng Laboratory, Shenzhen 518000, China
  • 6Optoelectronics Research Centre, University of Southampton, Southampton SO171BJ, UK
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    Figures & Tables(7)
    Polarization-insensitive silicon optical modulator based on two-dimensional gratings. (a) Schematic diagram of the polarization-insensitive silicon optical modulator. (b) Schematic diagram of the 2D grating coupler. (c) Schematic diagram of the cross-sectional view of the phase shifter. (d) Simulated near-field optical intensity profile of the grating diffraction mode with light incident from the four access waveguides. (e) Simulated far-field optical intensity profile of the grating diffraction mode. (f) Simulated microwave mode profile of the CPW electrodes for a frequency of 40 GHz. (g) Calculated coupling efficiency (CE), upward backreflection (Rub), and waveguide backreflection (Rwb) of the optimized grating coupler design. (h) Calculated EO S21 of the modulator as a function of frequency and applied bias voltage.
    (a) Microscope image of the fabricated polarization-insensitive silicon optical modulator. (b) SEM image of the optical fiber interface with an oxide cladding showing the opening for grating couplers. (c) SEM image of the optical fiber interface after oxide cladding removal showing the grating coupler, taper waveguides, and waveguide crossing. (d) Zoomed-in SEM image of the O-band 2D grating coupler. (e) SEM image of the optical waveguide crossing. (f) SEM image of the transition between channel waveguides and rib waveguides of the phase shifter. (g) SEM image of the cross-section of the whole phase shifter. (h) Zoomed-in SEM image of the rib waveguides in the phase shifter.
    Static performance characterization results. (a) Measured fiber-to-fiber IL and PDL of a back-to-back configuration of the O-band 2D GCs with balanced waveguide arms. (b) Measured fiber-to-fiber IL and PDL of the proposed modulator. (c) Measured fiber-to-fiber IL and PDL of a standard Mach–Zehnder modulator. (d) Measured fiber-to-fiber optical transmission spectra of the proposed modulator with different applied voltages ranging from 0 to 6 V. (e) Static ER with respect to wavelength under different incident SOPs. (f) Zoomed-in view of the static ER under different incident SOPs at the short span of central coupling wavelengths.
    Dynamic performance characterization. (a) Experimental setup of the dynamic performance measurement. TL, tunable laser; PC, polarization controller; AWG, arbitrary waveform generator; OFA, optical fiber amplifier; LCA, lightwave component analyzer; VNA, vector network analyzer; DCA, digital communication analyzer. (b) EO bandwidth (S21 parameter) of the optical modulator under different bias voltages for an incident polarization of 45° linear. (c) EO bandwidth (S21 parameter) of the optical modulator under different incident polarizations with a bias voltage of 5 V.
    (a)–(d) Selected eye diagrams for OOK modulation at 72, 90, 100, and 112 Gbaud, with the original eyes and eyes enabled by five-tap FFE shown for comparison. (e), (f) Selected eye diagrams for 100 and 112 Gbaud PAM4 modulation enabled by 32-tap FFE.
    (a) Eight different input SOPs of 0° linear (L0°), 45° linear (L45°), 90° linear (L90°), 135° linear (L135°), left-handed circular (LCP), right-handed circular (RCP), and two random SOP1 and SOP2 shown on the Poincaré sphere. (b) Average power, ER, and SNR of the 100 Gbaud OOK modulation eye diagrams as a function of input polarization states.
    • Table 1. Comparison of Key Performance Metrics for Experimentally Demonstrated Polarization-Insensitive EO Modulatorsa

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      Table 1. Comparison of Key Performance Metrics for Experimentally Demonstrated Polarization-Insensitive EO Modulatorsa

      ReferencePlatform and TypeVπLπ(V·cm)PDL (dB)IL (dB)Speed (Gb/s)BW at VbFootprintb
      [19]SOI (MZM)112.315c40 (OOK)27 GHz at –3 V1.35 mm
      [20]Ge/SiGe (MQW)N.A.3.537.5cN.A.8.8 GHz900 μm
      [33]SOI (MRM)N.A.N.A.5.5c22.8 (QPSK)<10 GHz at –2 V200  μm
      [36]TFLN (MZM)6.20.352c100 (PAM4)50 GHz20 mm
      This workSOI (MZM)1.50.153.38c224 (PAM4)49.8 GHz at –5 V2.5 mm
      9d
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    Zanyun Zhang, Beiju Huang, Qixin Wang, Zilong Chen, Ke Li, Kaixin Zhang, Meixin Li, Hao Jiang, Jiaming Xing, Tianjun Liu, Xiaoqing Lv, Graham T. Reed, "Polarization-insensitive silicon intensity modulator with a maximum speed of 224 Gb/s," Photonics Res. 13, 274 (2025)

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    Paper Information

    Category: Silicon Photonics

    Received: Aug. 7, 2024

    Accepted: Nov. 7, 2024

    Published Online: Jan. 8, 2025

    The Author Email: Beiju Huang (bjhuang@semi.ac.cn)

    DOI:10.1364/PRJ.538823

    CSTR:32188.14.PRJ.538823

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