Optically Readable Waveguide-Integrated Electrochromic Artificial Synaptic Device for Photonic Neuromorphic Systems

Abstract

Despite advances in numerous artificial synaptic devices, the search for a new functionalized synaptic device remains the subject of rigorous investigation for constructing neuromorphic systems. Optical readout functionality in artificial synapses is interesting as on-chip photonic integration technology could increase bandwidth and signal transmission, stop signal interference, reduce power loss, and provide degrees of freedom that complete the photonic neuromorphic system using light rather than electrons. Here, a waveguide-integrated electrochromic artificial synaptic device in which the electrolyte-gated electrical synaptic signal is read by optical means is demonstrated. The optically readable electrochromic synaptic device successfully imitates essential synaptic functions, such as short-and long-term plasticity, excitatory and inhibitory postsynaptic potentiation, and paired-pulse facilitation. In addition, randomly accessible nonvolatile multilevel optical memories are also demonstrated based on electrolyte ion dynamics that enable electrical switching of the transparency of the electrochromic material in a nonvolatile manner. This optically readable artificial synapse approach based on photonic integration circuit technologies provides insight into an exact reading of the emulation of the biological synapse in an optical manner and is a key step toward the implementation of non-conventional photonic neuromorphic systems with tunable bio-inspired synaptic functions.

Realization of Enhanced Long‐Term Visual Memory for Indium–Gallium–Zinc Oxide‐Based Optical Synaptic Transistor

“…[ 14–17 ] Therefore, in order to improve the visual information processing efficiency, optical synapses are also developed where it has both the synaptic functions and the photo‐sensing abilities. [ 18–33 ]…”

“…[14][15][16][17] Therefore, in order to improve the visual information processing efficiency, optical synapses are also developed where it has both the synaptic functions and the photo-sensing abilities. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Different types of devices, such as memristors, field-effect transistors, and phase change memories, have been studied for the application of artificial synapses. [16,18,19,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]44] Additionally, numerous materials including but not limited to low-dimensional materials, perovskites, oxide semiconductors, and organic materials have been applied to artificial synapses.…”

Flexible Artificial Synapses with a Biocompatible Maltose–Ascorbic Acid Electrolyte Gate for Neuromorphic Computing

“…As an important component of artificial neural systems, synaptic transistors that can simulate synaptic behavior and implement synapse calculations have gradually attracted the attention of researchers. − Electrolyte-gated synaptic transistors (EGSTs), as a form of artificial synapses, have attracted a great deal of research interest in recent years. − EGSTs have a number of advantages over transistors with a silicon oxide dielectric layer. The main motivation for using an electrolyte gate in transistors is the huge capacitance of the electrolyte, which allows transistor operation at low voltage (<2 V).…”

“…The human brain is mainly composed of a neural network consisting of around 10 11 neurons and around 10 15 synapses, making it robust, plastic, and fault-tolerant, and it has extremely low energy consumption (<20 W). 1−3 Enlightened by the working mechanism of the brain, there have been many attempts to fabricate artificial neuromorphic electronics to imitate the behaviors of biological neural systems.…”

On-chip high ion sensitivity electrochromic nanophotonic light modulator

“…On the other hand, electrochromic waveguide technology makes use of the ion concentration dependency of the EC effect for pH sensing, 17,18 ion concentration sensing in gases and liquids, 19,20 and the design of artificial synapses. 21 The coloration effect in EC materials (e.g. WO 3 ) are found to correlate with the concentration of ionic species within the solution.…”