Continuous Calibration of Microring Weights for Analog Optical Networks

Continuously configurable weighted addition is a key function for multivariate analog signal processing. The wavelength-division multiplexed version of weighted addition based on microrings can apply the strengths of photonic integration, wideband photonic information processing, and multi-wavelength networks toward new approaches to ultrafast analog distributed processing. In this letter, we experimentally demonstrate single-channel functionality using a 5-GHz signal, showing a continuous range of complementary (+/-) weighting in a bank of silicon microrings using a feedforward controller and balanced detection technique. Weight tuning accuracy with a dynamic range of 9.2 dB (i.e., 3.1 bits) is shown, and steps to improve performance are discussed. Systems of more microring weights and weight banks could address hitherto unsolvable problems in real-time radio frequency processing and high-performance control.