Flexible generation of structured terahertz fields via programmable exchange-biased spintronic emitters

TL;DR

This paper introduces a programmable spintronic emitter capable of flexibly generating various structured terahertz waves by precisely programming magnetization patterns, enabling advanced applications in microscopy, communication, and quantum information.

Contribution

The work presents a novel, high-resolution, programmable spintronic device for generating diverse structured terahertz fields through laser-assisted magnetization patterning.

Findings

Successfully generated various structured terahertz polarization states

Demonstrated control over spatially separated circular polarizations

Enabled design of complex far-field terahertz patterns

Abstract

Structured light, particularly in the terahertz frequency range, holds considerable potential for a diverse range of applications. However, the generation and control of structured terahertz radiation pose major challenges. In this work, we demonstrate a novel programmable spintronic emitter that can flexibly generate a variety of structured terahertz waves. This is achieved through the precise and high-resolution programming of the magnetization pattern on the emitter surface, utilizing laser-assisted local field cooling of an exchange-biased ferromagnetic heterostructure. Moreover, we outline a generic design strategy for realizing specific complex structured terahertz fields in the far field. Our device successfully demonstrates the generation of terahertz waves with diverse structured polarization states, including spatially separated circular polarizations, azimuthal or radial polarization states, and a full Poincare beam. This innovation opens a new avenue for designing and generating structured terahertz radiations, with potential applications in terahertz microscopy, communication, quantum information, and light-matter interactions.