# Near-perfect absorber as a subwavelength thickness spatial frequency filter for optical image processing

## TL;DR

This paper demonstrates an on-chip, all-optical spatial frequency filter using a near-perfect absorber, enabling efficient edge enhancement and phase gradient conversion without bulky equipment or computational processing.

## Contribution

It introduces a novel thin-film perfect absorber structure for on-chip, all-optical spatial frequency filtering, reducing the need for bulky optical systems or computational methods.

## Key findings

- Successful experimental demonstration of on-chip spatial frequency filtering
- Effective edge enhancement in amplitude images
- Conversion of phase gradients into intensity modulations

## Abstract

Spatial frequency filtering is a fundamental enabler of information processing methods in biological and technical imaging. Most filtering methods, however, require either bulky and expensive optical equipment or some degree of computational processing. Here we experimentally demonstrate on-chip, all-optical spatial frequency filtering using a thin-film perfect absorber structure. We give examples of edge enhancement in an amplitude image as well as conversion of a phase gradient in a wave field into an intensity modulation.