# Tuning 2D hyperbolic plasmons in black phosphorus

## TL;DR

This paper demonstrates that atomically thin black phosphorus can be engineered as a hyperbolic material across a broad spectrum, with tunable plasmonic properties influenced by gain and loss mechanisms.

## Contribution

It introduces the concept of tuning 2D hyperbolic plasmons in black phosphorus through engineering and gain, expanding its potential for plasmonic applications.

## Key findings

- Black phosphorus can operate as a hyperbolic material from visible to ultraviolet spectrum.
- Introduction of optical gain creates a new hyperbolic region in the infrared.
- Hyperbolic plasmon characteristics depend on gain-loss interplay along crystalline directions.

## Abstract

Black phosphorus presents a very anisotropic crystal structure, making it a potential candidate for hyperbolic plasmonics, characterized by a permittivity tensor where one of the principal components is metallic and the other dielectric. Here we demonstrate that atomically thin black phosphorus can be engineered to be a hyperbolic material operating in a broad range of the electromagnetic spectrum from the entire visible spectrum to ultraviolet. With the introduction of an optical gain, a new hyperbolic region emerges in the infrared. The character of this hyperbolic plasmon depends on the interplay between gain and loss along the two crystalline directions.