Microring Weight Banks

Microring weight banks could enable novel signal processing approaches in silicon photonics. We analyze factors limiting channel count in microring weight banks, which are central to analog wavelength-division multiplexed processing networks in silicon. We find that microring weight banks require a fundamentally different analysis compared to other wavelength-division multiplexing circuits (e.g., demultiplexers). By introducing a quantitative description of independent weighting, we establish performance tradeoffs between channel count and power penalty. This performance is significantly affected by coherent multiresonator interactions through bus waveguides. We experimentally demonstrate these effects in a fabricated device. Analysis relies on the development of a novel simulation technique combining parametric programming with generalized transmission theory. Experimental measurement fitting of an 8-channel weight bank is presented as an example of another application of the simulator.