Investigation On The Spiking Dynamic Characteristics Based On VCSELs Photonic Neurons

Brain science research has received widespread attention since the 1980 s.The rise of artificial neural networks has gradually become a research hotspot in the field of artificial intelligence.At present,artificial neural networks have developed into the third generation of spiking neural networks after the first generation of perceptron models and the second generation of B-P neural networks.The implementation of the spiking neural network model has focused on electrical methods,although these neurological techniques can effectively deal with the biological behavior of biological nerves,the electrical neuromorphic system is often limited by bandwidth,distance,and power consumption.In recent years,photonic neural models based on semiconductor optical amplifiers,fiber lasers,semiconductor lasers and other different photonic neural models have been proposed one after another because they can break through the limitation of electronic device bandwidth and provide super-fast spiking dynamics.Vertical cavity surface emitting lasers(VCSELs)may be become an ideal device for neuromorphic photonics because of its unique advantages of low cost,low power consumption,easy integration into two-dimensional arrays,and high coupling efficiency with optical fibers.Therefore,further study of the ultra-fast spiking dynamic properties of VCSEL photonic neurons is a great significance for promoting the development and application of VCSEL in artificial neural networks.In this thesis,we based on the spin-flip mode(SFM)of VCSELs,the spiking dynamics of VCSELs photon neurons are simulated.For a single perturbation condition,the laser can excite an ultrafast spikes signal about 8 orders of magnitude faster than a biological neuron under appropriate injection conditions.When the intensity of the disturbance signal is small,the VCSEL cannot excite the spike signal.A spike signal can only be excited by the VCSEL when the intensity of the disturbance signal exceeds a certain level,and the repetition frequency of the spikes signal increases as the intensity of the disturbance signal increases.In addition,as the duration of the disturbance increases,the number of spikes excited by the VCSEL can be increases.In the case of two consecutive pulse disturbance,reducing the time interval between the two disturbances causes the system only respond to the first disturbance due to system refractory period.The time of the laser refractory period may decrease when the duration of the disturbance or the intensity of the disturbance decreases,and under appropriate disturbance conditions,the laser may respond to two consecutive disturbance signals.For two unidirectionally coupled VCSEL-based neuron,by controlling the disturbance time and disturbance intensity of the disturbance signal,the spike signal excited by the transmitting VCSEL(T-VCSEL)can be effectively suppressed within the time of the external disturbance signal.This suppressed spike signal can be transmitted to another receiving VCSEL(R-VCSEL),and the two VCSELs have similar responses.As the disturbance intensity increases,the spikes signal with higher amplitude and lower oscillation frequency can be observed during the perturbation time.When the disturbance intensity increases to a certain threshold,the laser enters the injection-locked state from the excited state,and the VCSEL excited spikes signal can be completely suppressed in the disturbance signal region.In addition,the spiking time window of the suppression region can be controlled through adjusting perturbation duration.