Single carbon nanotubes as ultrasmall all-optical memories

TL;DR

This paper demonstrates an all-optical memory device using individual carbon nanotubes, where molecular adsorption and desorption induce optical bistability, enabling ultra-small, reversible, and reproducible memory operation at the nanoscale.

Contribution

It introduces a novel nanoscale all-optical memory based on carbon nanotubes exploiting molecular adsorption effects, surpassing the diffraction limit for device miniaturization.

Findings

Reversible optical switching between adsorbed and desorbed states.

Memory rewriting speed determined by molecular adsorption/desorption times.

Potential for photonic devices significantly smaller than optical wavelengths.

Abstract

Performance improvements are expected from integration of photonic devices into information processing systems, and in particular, all-optical memories provide a key functionality. Scaling down the size of memory elements is desirable for high-density integration, and the use of nanomaterials would allow for devices that are significantly smaller than the operation wavelengths. Here we report on all-optical memory based on individual carbon nanotubes, where adsorbed molecules give rise to optical bistability. By exciting at the high-energy tail of the excitonic absorption resonance, nanotubes can be switched between the desorbed state and the adsorbed state. We demonstrate reversible and reproducible operation of the nanotube optical memory, and determine the rewriting speed by measuring the molecular adsorption and desorption times. Our results underscore the impact of molecular-scale effects on optical properties of nanomaterials, offering new design strategies for photonic devices that are a few orders of magnitude smaller than the optical diffraction limit.