We report on the direct intensity modulation characteristics of a high-speed resonant tunneling diode-photodetector (RTD-PD) with an oscillation frequency of 79 GHz. This work demonstrates both electrical and optical modulation and shows that RTD-PD oscillators can be utilized as versatile optoelectronic/radio interfaces. This is the first demonstration of optical modulation of an RF carrier using integrated RTD-PD oscillators at microwave frequencies.

We investigate the dynamic behaviour of resonant tunneling diode-photodetectors (RTD-PDs) in which the excitability can be activated by either electrical noise or optical signals. In both cases, we find the characteristics of the stochastic spiking behavior are not only dependent on the biasing positions but also controlled by the intensity of the input perturbations. Additionally, we explore the ability of RTD-PDs to perform optical signal transmission and neuromorphic spike generation simultaneously. These versatile functions indicate the possibility of making use of RTD-PDs for innovative applications, such as optoelectronic neuromorphic circuits for spike-encoded signaling and data processing.

This paper represents the experimental results of optical modulation characteristics of a resonant tunneling diodephotodiode (RTD-PD) device and novel microwave oscillators employing such RTD-PD. Different from a pure electronic RTD oscillator, the RTD-PDs in this work contain photoconductive layers which make it able to operate in optical conditions. A beam of intensity modulated light with a wavelength of 1310 nm was sent to the free running oscillator via an optical fiber whilst the RTD device was biased in the oscillation condition, and the corresponding electrical data can be extracted from the output port of the oscillator. A square wave signal at data rates up to 10 Gbit/s, and a pseudo random binary sequence (PRBS) signal with a data rate of 100 Mbit/s were preliminarily implemented for modulation.

Optoelectronic spiking neurons are regarded as highly promising systems for novel light-powered neuromorphic computing hardware. Here, we investigate an optoelectronic (O/E/O) spiking neuron built with an excitable resonant tunnelling diode (RTD) coupled to a photodetector and a vertical-cavity surface-emitting laser (VCSEL). This work provides the first experimental report on the control of the amplitude (weighting factor) of the fired optical spikes directly in the neuron, introducing a simple way for presynaptic spike amplitude tuning. Notably, a very simple mechanism (the control of VCSEL bias) is used to tune the amplitude of the spikes fired by the optoelectronic neuron, hence enabling an easy and high-speed option for the weighting of optical spiking signals in future interconnected photonic spike-processing nodes. Furthermore, we validate the feasibility of this layout using a simulation of a monolithically-integrated, RTD-powered, nanoscale optoelectronic spiking neuron model, confirming the system’s potential for delivering weighted optical spiking signals at very high speeds (GHz firing rates). These results demonstrate the high degree of flexibility of RTD-based artificial optoelectronic spiking neurons and highlight their potential towards compact, high-speed and low-energy photonic spiking neural networks for use in future, light-enabled neuromorphic hardware.