# An Epsilon‐Near‐Zero‐Based Nonlinear Platform for Ultrafast Re‐Writable Holography

## TL;DR

This paper introduces a new ultrafast and re-writable holography platform using a thin ITO film that enables efficient optical modulation and computation.

## Contribution

The use of epsilon-near-zero materials for ultrafast re-writable holography with broad bandwidth and no complex nanofabrication.

## Key findings

- A subwavelength-thick ITO film achieves ultrafast re-writable holography with high diffraction efficiency.
- The platform operates over a 300-nm bandwidth and is six orders of magnitude faster than standard materials.
- Applications include spatial structuring of light and optical computation without complex fabrication.

## Abstract

We re‐examine real‐time holography for all‐optical structuring of light and optical computation using a contemporary material: a subwavelength‐thick, spatially unstructured film of indium tin oxide (ITO). When excited by spatially structured light at epsilon‐near‐zero frequencies, the film acts as an efficient and reconfigurable diffractive optical platform for all‐optical modulation of light such as spatial structuring and optical computations. We demonstrate a few percent of absolute diffraction efficiency over greater than 300‐nm‐bandwidth around telecom wavelengths using a film four orders of magnitude thinner than and up to six orders of magnitude faster than standard holographic materials. Our findings highlight the potential of using epsilon‐near‐zero‐based nanostructures for efficient modulation of spatially structured light and rapid prototyping without complex nanofabrication processes.

We show that an unstructured, sub‐wavelength thick epsilon‐near‐zero material, such as ITO, can be efficiently used for ultrafast re‐writable holography over a broad bandwidth range. We showcase two powerful applications of our scheme, that is, spatial structuring of light and optical computation.