Electrical Control of Linear Dichroism in Black Phosphorus from the Visible to Mid-Infrared

TL;DR

This paper demonstrates the first electrically tunable linear dichroism in black phosphorus, enabling dynamic control of light polarization across visible to mid-infrared wavelengths through quantum-confined effects.

Contribution

It introduces black phosphorus as a new material for electrically tunable linear dichroism in photonic devices, expanding tunable optical functionalities.

Findings

Active modulation of linear dichroism from visible to mid-infrared

High absorption modulation strengths approaching unity

Tunable effects driven by quantum-confined Stark and Burstein-Moss phenomena

Abstract

The incorporation of electrically tunable materials into photonic structures such as waveguides and metasurfaces enables dynamic control of light propagation by an applied potential. While many materials have been shown to exhibit electrically tunable permittivity and dispersion, including transparent conducting oxides (TCOs) and III-V semiconductors and quantum wells, these materials are all optically isotropic in the propagation plane. In this work, we report the first known example of electrically tunable linear dichroism, observed here in few-layer black phosphorus (BP), which is a promising candidate for multi-functional, broadband, tunable photonic elements. We measure active modulation of the linear dichroism from the mid-infrared to visible frequency range, which is driven by anisotropic quantum-confined Stark and Burstein-Moss effects, and field-induced forbidden-to-allowed optical transitions. Moreover, we observe high BP absorption modulation strengths, approaching unity for certain thicknesses and photon energies.