Check out this new article: https://www.osa.org/en-us/about_osa/newsroom/news_releases/2018/researchers_move_closer_to_completely_optical_arti/ https://www.osa

Check out this new article: https://www.osa.org/en-us/about_osa/newsroom/news_releases/2018/researchers_move_closer_to_completely_optical_arti/ https://www.osa.org/en-us/about_osa/newsroom/news_releases/2... They implemented a back propagation algorithm using just optical.