# Strong-field nonlinear optical properties of monolayer black phosphorus

## TL;DR

This paper reveals the strong-field nonlinear optical properties of monolayer black phosphorus through first-principles simulations, demonstrating its superior high harmonic generation capabilities compared to other 2D materials, with implications for ultrafast nanophotonics.

## Contribution

It provides the first nonperturbative analysis of high harmonic generation in monolayer black phosphorus, highlighting its potential for extreme-ultraviolet applications.

## Key findings

- BP exhibits higher HHG cutoff energy than graphene, MoS2, and hBN.
- BP shows stronger spectral intensity in HHG.
- Study opens new avenues for ultrafast carrier dynamics research.

## Abstract

Within the past few years, atomically thin black phosphorus (BP) has been demonstrated as a fascinating new 2D material that is promising for novel nanoelectronics and nanophotonics applications, due to its many unique properties such as direct and widely tunable bandgap, high carrier mobility and remarkable intrinsic in-plane anisotropy. However, its important extreme nonlinear behavior and ultrafast dynamics of carriers under strong-field excitation have yet to be revealed to date. Herein, we report nonperturbative high harmonic generation (HHG) in monolayer BP by first-principles simulations. We show that BP exhibits extraordinary HHG properties, with clear advantages over three major types of 2D materials under intensive study, i.e., semimetallic graphene, semiconducting MoS$_2$, and insulating hexagonal boron nitride, in terms of HHG cutoff energy and spectral intensity. This study advances the scope of current research activities of BP into a new regime, suggesting its promising future in applications of extreme-ultraviolet and attosecond nanophotonics, and also opening doors to investigate the strong-field and ultrafast carrier dynamics of this emerging material.