West Virginia University
Magnetic Field Free Magneto-optics and Chiral Plasmonics with Dirac Materials
Reciprocity is a fundamental concept in optics. Basically it says that if I can see you, then you can see me. It means that if a light ray can travel from A to B, then it can also follow this trajectory in the opposite direction, from B to A. However in optical communications, breaking this reciprocity is crucial to prevent interference and protecting optical sources. Non-reciprocal devices would allow the transmission of signals in one direction while blocking those propagating in the opposite direction.
Achieving non-reciprocity generally requires breaking time-reversal symmetry. This can be accomplished in magneto-optical materials under an external magnetic field. However, such devices tend to be bulky, costly and not CMOS compatible, motivating the on-going search for alternative strategies to break reciprocity for on-chip integration.
West Virginia University's approach is to explore a new class of material, gapped Dirac materials such as single layer transition metal dichalcogenides, where the breaking of inversion symmetry and large spin orbit coupling leads to valley-spin locking. Their intrinsic Berry curvature further acts as an effective magnetic field in momentum space, giving rise to chiral plasmons at mid IR and THz frequencies. Our goal is to achieve magnetic-field-free nonreciprocal light transport based on these properties.