Photochemical and electro-optic devices for neuromorphic photonics in silicon

Date
Aug 5, 2024, 1:00 pm2:30 pm
Location
EQUAD B327

Speaker

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Event Description

The training and usage of artificial neural networks forms an increasingly large fraction of total compute. Traditional Von-Neumann digital hardware, however, struggles to efficiently emulate neural computation models. Furthermore, it no longer offers guaranteed improvements due to the slowdown of Moore's Law. As such, there is renewed interest in developing neuron-like (neuromorphic) hardware. Neuromorphic photonics, the emulation of neural compute using photonic components, is particularly attractive due to the inherent suitability of light for communication. Photonic integrated circuits (PICs), and specifically silicon photonics, promises the manufacturing scale for its realization. This thesis consists of a collection of results related to neuromorphic photonics in silicon. It begins with a short survey of ``standard'' silicon photonic neurons, explored through a series of software, designs, and packages co-developed as part of this work. It is then followed by the demonstrations of new silicon photonic devices with built-in neuromorphic functionality. The first device presented is a microring resonator weight configured by the photochemical tuning of a photochromic cladding, an example of on-chip analog memory. To our knowledge, this constitutes one of the first demonstration of commercial-grade, backend compatible light molecule deposition enhancing a silicon PIC. We show interesting properties of this all-optical memory for a silicon photonics platform, including nonvolatility, low-loss in the optical C-band, and first-order photokinetics of the photoconversion leading to continuous, bidirectional, scalable actuation. The limitations of this device are also discussed, namely stability and speed. We then carefully show through computation that, operating in the visible band, this device fulfills the "fingerprints" for a generic memristive device. To our knowledge, this is the first ``bottom-up'' exploration of an optical memristive device. Finally, we discuss another device: a capacitively-driven silicon microring resonator colocated with a capacitive analog memory. Unlike the previous example, this memory is volatile, but offers higher reconfiguration speeds. 

Adviser: Paul Prucnal