Tait Alexander N, Jayatilleka Hasitha, De Lima Thomas Ferreira, Ma Philip Y, Nahmias Mitchell A, Shastri Bhavin J, Shekhar Sudip, Chrostowski Lukas, Prucnal Paul R
Opt Express. 2018 Oct 1;26(20):26422-26443. doi: 10.1364/OE.26.026422.
Microring weight banks present novel opportunities for reconfigurable, high-performance analog signal processing in photonics. Controlling microring filter response is a challenge due to fabrication variations and thermal sensitivity. Prior work showed continuous weight control of multiple wavelength-division multiplexed signals in a bank of microrings based on calibration and feedforward control. Other prior work has shown resonance locking based on feedback control by monitoring photoabsorption-induced changes in resistance across in-ring photoconductive heaters. In this work, we demonstrate continuous, multi-channel control of a microring weight bank with an effective 5.1 bits of accuracy on 2Gbps signals. Unlike resonance locking, the approach relies on an estimate of filter transmission versus photo-induced resistance changes. We introduce an estimate still capable of providing 4.2 bits of accuracy without any direct transmission measurements. Furthermore, we present a detailed characterization of this response for different values of carrier wavelength offset and power. Feedback weight control renders tractable the weight control problem in reconfigurable analog photonic networks.
微环权重库为光子学中可重构的高性能模拟信号处理带来了新机遇。由于制造工艺的差异和热敏感性，控制微环滤波器的响应是一项挑战。先前的工作表明，基于校准和前馈控制，可以对微环库中的多个波分复用信号进行连续权重控制。其他先前的工作还展示了通过监测环内光电导加热器上光吸收引起的电阻变化，基于反馈控制实现的共振锁定。在这项工作中，我们展示了对微环权重库的连续多通道控制，在2Gbps信号上有效精度达到5.1比特。与共振锁定不同，该方法依赖于滤波器传输与光致电阻变化的估计。我们引入了一种估计方法，无需任何直接传输测量就能提供4.2比特的精度。此外，我们针对不同的载波波长偏移和功率值，对这种响应进行了详细表征。反馈权重控制使得可重构模拟光子网络中的权重控制问题变得易于处理。
