7 March 2016 Adaptive gain, equalization, and wavelength stabilization techniques for silicon photonic microring resonator-based optical receivers
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Interconnect architectures based on high-Q silicon photonic microring resonator devices offer a promising solution to address the dramatic increase in datacenter I/O bandwidth demands due to their ability to realize wavelength-division multiplexing (WDM) in a compact and energy efficient manner. However, challenges exist in realizing efficient receivers for these systems due to varying per-channel link budgets, sensitivity requirements, and ring resonance wavelength shifts. This paper reports on adaptive optical receiver design techniques which address these issues and have been demonstrated in two hybrid-integrated prototypes based on microring drop filters and waveguide photodetectors implemented in a 130nm SOI process and high-speed optical front-ends designed in 65nm CMOS. A 10Gb/s powerscalable architecture employs supply voltage scaling of a three inverter-stage transimpedance amplifier (TIA) that is adapted with an eye-monitor control loop to yield the necessary sensitivity for a given channel. As reduction of TIA input-referred noise is more critical at higher data rates, a 25Gb/s design utilizes a large input-stage feedback resistor TIA cascaded with a continuous-time linear equalizer (CTLE) that compensates for the increased input pole. When tested with a waveguide Ge PD with 0.45A/W responsivity, this topology achieves 25Gb/s operation with -8.2dBm sensitivity at a BER=10-12. In order to address microring drop filters sensitivity to fabrication tolerances and thermal variations, efficient wavelength-stabilization control loops are necessary. A peak-power-based monitoring loop which locks the drop filter to the input wavelength, while achieving compatibility with the high-speed TIA offset-correction feedback loop is implemented with a 0.7nm tuning range at 43μW/GHz efficiency.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Samuel Palermo, Samuel Palermo, Patrick Chiang, Patrick Chiang, Kunzhi Yu, Kunzhi Yu, Rui Bai, Rui Bai, Cheng Li, Cheng Li, Chin-Hui Chen, Chin-Hui Chen, Marco Fiorentino, Marco Fiorentino, Ray Beausoleil, Ray Beausoleil, Hao Li, Hao Li, Ayman Shafik, Ayman Shafik, Binhao Wang, Binhao Wang, Alex Titriku, Alex Titriku, "Adaptive gain, equalization, and wavelength stabilization techniques for silicon photonic microring resonator-based optical receivers", Proc. SPIE 9775, Next-Generation Optical Networks for Data Centers and Short-Reach Links III, 97750K (7 March 2016); doi: 10.1117/12.2214888; https://doi.org/10.1117/12.2214888

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