Optical neural network chip can identify patterns by enabling light to naturally represent negative as well as positive numbers

https://www.eurekalert.org/news-releases/1115475

"brightness not negative so forced to either use electronic components to handle negative values (causing delays) or limit AI to simpler, less stable non-negative math... overcome using 2 microring resonators at different wavelengths representing positive/ negative values... cascadable nonlinear activation, Mach–Zehnder interferometer mesh... modeled generator that uses natural optical noise as an input, 98% accurate Iris classification... optical-to-optical image generation without need for digital-to-analog conversion"