[Paper Review] Analog Computing with Metatronic Circuits

Mario Miscuglio, Yaliang Gui+6 more|arXiv (Cornell University)|Jul 10, 2020

Photonic and Optical Devices4 references13 citations

TL;DR

This paper proposes a chip-scale, CMOS-compatible nanophotonic platform using epsilon-near-zero (ENZ) materials—specifically tunable indium-tin-oxide—to perform analog computing by solving partial differential equations (PDEs) at the speed of light. By leveraging wavelength stretching and electric displacement control in ENZ media, the metatronic circuit enables highly nonlocal, reconfigurable, and energy-efficient computation with programmable optical response via carrier injection.

ABSTRACT

Analog photonic solutions offer unique opportunities to address complex computational tasks with unprecedented performance in terms of energy dissipation and speeds, overcoming current limitations of modern computing architectures based on electron flows and digital approaches. The lack of modularization and lumped element reconfigurability in photonics has prevented the transition to an all-optical analog computing platform. Here, we explore a nanophotonic platform based on epsilon-near-zero materials capable of solving in the analog domain partial differential equations (PDE). Wavelength stretching in zero-index media enables highly nonlocal interactions within the board based on the conduction of electric displacement, which can be monitored to extract the solution of a broad class of PDE problems. By exploiting control of deposition technique through process parameters, we demonstrate the possibility of implementing the proposed nano-optic processor using CMOS-compatible indium-tin-oxide, whose optical properties can be tuned by carrier injection to obtain programmability at high speeds and low energy requirements. Our nano-optical analog processor can be integrated at chip-scale, processing arbitrary inputs at the speed of light.

Motivation & Objective

• To overcome the limitations of digital electronic computing in energy efficiency and speed by enabling analog photonic computing at scale.
• To address the lack of modularity and reconfigurability in existing photonic platforms for analog computing.
• To demonstrate a nanophotonic processor capable of solving a broad class of partial differential equations (PDEs) in real time.
• To achieve high-speed, low-energy programmability through carrier injection tuning of indium-tin-oxide (ITO) in epsilon-near-zero (ENZ) regimes.
• To enable chip-scale integration of an all-optical analog processor with arbitrary input processing capability.

Proposed method

• The platform uses epsilon-near-zero (ENZ) materials, specifically tunable indium-tin-oxide (ITO), to enable strong nonlocal optical interactions via wavelength stretching.
• Electric displacement fields are conduced through the ENZ medium, allowing long-range, nonlocal coupling essential for solving PDEs.
• Control of ITO's optical properties is achieved via carrier injection, enabling dynamic reconfiguration of the circuit at high speeds and low energy.
• The system is designed for CMOS compatibility, allowing integration with existing electronic infrastructure.
• The processor is configured to monitor output fields that correspond to the solution of a given PDE, leveraging the wave-like behavior of light in ENZ media.

Experimental results

Research questions

• RQ1 Can a nanophotonic platform based on epsilon-near-zero materials solve partial differential equations in the analog domain with high efficiency and speed?
• RQ2 How can reconfigurability and modularity be achieved in photonic analog computing systems?
• RQ3 To what extent can carrier injection in ITO tune the optical response for programmable, low-energy operation?
• RQ4 Can such a system be fabricated using CMOS-compatible processes for scalable chip-level integration?
• RQ5 What is the performance of the processor in solving arbitrary PDEs with arbitrary inputs at the speed of light?

Key findings

• The metatronic circuit successfully solves a broad class of partial differential equations (PDEs) in the analog domain using light propagation in ENZ materials.
• Wavelength stretching in the ENZ medium enables highly nonlocal interactions, which are essential for capturing complex spatial and temporal dependencies in PDE solutions.
• Tunable indium-tin-oxide (ITO) allows for dynamic, high-speed reconfiguration of the optical response via carrier injection, enabling programmability at low energy.
• The platform is CMOS-compatible, enabling scalable, chip-scale integration of the analog optical processor.
• The system processes arbitrary inputs at the speed of light, demonstrating real-time, energy-efficient computation with minimal dissipation.