# Ideal optical antimatter using passive lossy materials under complex frequency excitation

## TL;DR

This paper shows that passive, lossy materials can act as optical antimatter when illuminated with light at complex frequencies, overcoming previous limitations.

## Contribution

The novel contribution is using complex frequency excitation to enable optical antimatter with positive-index materials.

## Key findings

- Passive, lossy materials can realize optical antimatter under complex frequency excitation.
- Materials with a positive index at real frequencies can behave as negative-index materials under complex excitation.
- Numerical demonstrations include double focusing and superscattering using the proposed approach.

## Abstract

The original concept of left-handed material has inspired the possibility of optical antimatter, where the effect of light propagation through a medium can be completely canceled by its complementary medium. Despite recent progress in the development of negative-index metamaterials, losses continue to be a significant barrier to realizing optical antimatter. In this work, we show that passive, lossy materials can be used to realize optical antimatter when illuminated by light at a complex frequency. We further establish that one can engineer arbitrary complex-valued permittivity and permeability in such materials. Strikingly, we show that materials with a positive index at real frequencies can act as negative-index materials under complex frequency excitation. Using our approach, we numerically demonstrate the optical antimatter functionality, as well as double focusing by an ideal perfect lens and superscattering. Our work demonstrates the power of temporally structured light in unlocking the promising opportunities of complementary media, which have until now been inhibited by material loss.

Passive, lossy materials with positive index at real frequencies can be used to realize optical antimatter under complex frequency excitation. Our approach enables arbitrary complex \documentclass[12pt]{minimal}
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