Fig. 8
Progress and expansion of the diffractive optical neural network (DONN). a Reconfigurable diffractive processor unit (DPU)47. b Schematic of the DPU prototype47. c Feedforward DONN built based on DPU47. d Recurrent DONN built based on DPU47. e Programmable DONN based on digital-coding metasurfaces53. a–d Reproduced from ref. 47 with permission of Springer Nature: Nature Photonics. e Reproduced from ref. 53 with permission of Springer Nature: Nature Electronics
