Fig. 1. Structure of integrated optical interference unit (OIU) and confusion matrices of vowel recognition^[18].(a) Structure of OIU; (b) confusion matrices of vowel recognition by ONN and 64-bit computer

Fig. 2. Structure of delay line before OIU and logic and timing chart of the optical convolutional neural network^[19]. (a) Structure of delay line; (b) logic and timing chart

Fig. 3. Structures of recurrent neural networks^[20]. (a) Parallel structure; (b) serial structure

Fig. 4. Structure of optoelectronic recurrent neural network and classifying result of rectangular and sinusoid signals^[25]. (a) Structure of optoelectronic recurrent neural network; (b) classifying result

Fig. 5. Graphene excitable fiber laser^[29]

Fig. 6. Integrated photonic neuron and excitable response^[30]. (a) Integrated photonic neuron; (b) excitable response

Fig. 7. In situ training algorithm of integrated photonic neural networks^[38]

Fig. 8. Training results of optical neural network by adopting different algorithms^[39]. (a) GA algorithm; (b) PSO algorithm

Fig. 9. Structure of optoelectronic nonlinear module and implementing different nonlinear functions by tunning phase of MZI^[45]. (a) Structure of nonlinear module; (b) implementing different nonlinear functions

Fig. 10. Normalized transmission curve of optical controlled PCM^[46]

Fig. 11. Structure of D²NN and resolution improvement of imaging^[53]. (a) Structure D²NN; (b) resolution improvement result

Fig. 12. Structure of TS-NN^[54]

Fig. 13. Confusion matrices of different neural network structures^[54]. (a) Conventional neural network structure;(b) TS-NN without noise; (c) TS-NN with noise

Fig. 14. Structures of optoelectronic binarized neural network and weights mapping^[55]. (a) Structure of the optoelectronic binarized neural network; (b) mapping structure of binarized weights in single polarization system; (c) mapping structure of binarized weights in polarization multiplexing system

Fig. 15. OSNR-BER curves of single polarization and polarization multiplexing QPSK communication systems implemented by different methods^[55]. (a) Single polarization QPSK communication system; (b) polarization multiplexing QPSK communication system