All-Optical Excitable Spiking Laser Neuron in InP Generic Integration Technology

Brain-inspired, neuromorphic devices implemented in integrated photonic hardware have attracted significant interest recently as part of efforts towards novel non-von Neumann computing paradigms that make use of the low loss, high-speed and parallel operations in optics. An all-optical spiking laser neuron fabricated on the indium-phosphide generic integration technology platform may be a practical alternative to other semi-integrated photonic and electronic-based spiking neuron implementations. Owing to the large number of predefined building blocks, a plethora of applications have benefitted already from the generic integration process. This technology platform has now been utilised for the first time to demonstrate an all-optical spiking laser neuron. This paper present and discusses the design and measurement of the ultra-fast and rich spiking dynamics in these devices. We show that under external pulse injection and operated slightly below the lasing threshold, the laser neuron exhibits an excitable mode, in addition to a self-spiking mode far above the threshold when no pulse is injected. In the excitable mode, the required injected pulse energy is much lower than that of the generated excited response, meeting an important requirement for neuron cascadability. In addition, we investigate excitability at different injection wavelengths below the lasing wavelength, as well as the ultra-fast temporal properties of the spiking response. All of the discussed characteristics point to the laser neuron being an important candidate for scaling up to future fully-connected, multi-wavelength all-optical photonic spiking neural networks in indium-phosphide generic integration technology.