Cavity-Enhanced Linear Dichroism in a van der Waals Antiferromagnet

TL;DR

This paper demonstrates tunable linear dichroism in a van der Waals antiferromagnetic insulator using cavity coupling, enabling potential applications in quantum materials diagnostics and integrated photonic devices.

Contribution

It introduces a method to induce and control large in-plane optical anisotropy and linear dichroism in FePS3 via cavity coupling, a novel approach in this material class.

Findings

Achieved near-unity linear dichroism in visible-near infrared range.

Demonstrated spectral and magnitude tuning of LD through cavity parameters.

Derived dispersion relations of LD as a function of cavity length and material thickness.

Abstract

Optical birefringence is a fundamental optical property of crystals widely used for filtering and beam splitting of photons. Birefringent crystals concurrently possess the property of linear dichroism (LD) that allows asymmetric propagation or attenuation of light with two different polarizations. This property of LD has been widely studied from small molecules to polymers and crystals but has rarely been engineered per will. Here, we use the newly discovered spin-charge coupling in van der Waals antiferromagnetic (AFM) insulator FePS3 to induce large in-plane optical anisotropy and consequently LD. We report that the LD in this AFM insulator is tunable both spectrally and magnitude-wise as a function of cavity coupling. We demonstrate near-unity LD in the visible-near infrared range in cavity-coupled FePS3 crystals and derive its dispersion as a function of cavity length and FePS3 thickness. Our results hold wide implications for use of cavity tuned LD as a diagnostic probe for strongly correlated quantum materials as well as opens new opportunities for miniaturized, on-chip beam-splitters and tunable filters.