  Nonlinear dynamics of spiking neural networks has recently attracted much
interest as an approach to understand possible information processing in the
brain and apply it to artificial intelligence. Since information can be
processed by collective spiking dynamics of neurons, the fine control of
spiking dynamics is desirable for neuromorphic devices. Here we show that
photonic spiking neurons implemented with paired nonlinear optical oscillators
can be controlled to generate two modes of bio-realistic spiking dynamics by
changing the optical pump amplitude. When they are coupled in a network, we
found that the interaction between the photonic neurons induces an effective
change in the pump amplitude depending on the order parameter that
characterizes synchronization. The experimental results show that the effective
change causes spontaneous modification of the spiking modes and firing rates of
clustered neurons, and such collective dynamics can be utilized to realize
efficient heuristics for solving NP-hard combinatorial optimization problems.
