A Chiral Microcavity based on Apparent Circular Dichroism

TzuLing Chen^1,2*, Andrew Salij³, Katherine Parrish², Francesco Urraci⁴, Li-Zhi Lin¹, Yi-Jan Huang¹, Lorenzo Di Bari⁴, Roel Tempelaar³, Randall Goldsmith²

¹Department of Photonics, National Yang-Ming Chiao-Tung University, Hsinchu, Taiwan
²Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
³Department of Chemistry, Northwestern University, Evanston, IL, USA
⁴Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa, Italy

* Presenter:TzuLing Chen, email:tlc@nycu.edu.tw

Examining the disparity between left-handed and right-handed chiral optical modes in planar Fabry–Pérot (FP) microcavities presents a significant opportunity for a wide array of chiral light-matter phenomena, spanning applications in spintronics, polaritonics, and chiral lasing. Despite its potential, this symmetry breaking has remained largely unexplored, with most focus directed towards inventing mirrors, such as meta surface mirrors, where reflective properties can be altered.

In our study, we propose a direct approach to achieve chiral symmetry breaking in FP microcavities. We maintain low mode volumes by embedding organic thin films that display 'apparent circular dichroism' (ACD), an optical effect resulting from the interplay of linear birefringence and linear dichroism with offset optical axes. Importantly, ACD interactions exhibit opposing behaviors for counter-propagating light and strengthen with path length. Consequently, we have demonstrated substantial chiral asymmetry in cavity modes, surpassing the asymmetry observed in isolated thin films by over an order of magnitude.

Our investigation, employing both circular dichroism spectroscopy and simulations utilizing theoretical scattering matrix methods, comprehensively characterizes the spatial, spectral, and angular chiroptical responses of this innovative chiral microcavity configuration. This research illuminates new pathways for understanding and leveraging chiral light-matter interactions within microcavity systems.

Keywords: chiroptical spectroscopy, circular dichorism, micro-resonator, chiral polariton, Fabry–Pérot cavity