Reconfigurable and frequency-tunable optical nonreciprocity via quantum-critical polariton-assisted Autler-Townes effect
Phys. Rev. A 114, 033733 – Published 25 September, 2026
DOI: https://doi.org/10.1103/sc6z-sdtq
Abstract
Optical nonreciprocity with both reversible transmission direction and broad frequency tunability is highly desirable for flexible control of light propagation in integrated photonic systems. Here, we propose a scheme to realize reconfigurable and frequency-tunable optical nonreciprocity in a coupled dual whispering-gallery-mode resonator with optomechanical interactions. A strong directional driving field is selectively applied to the clockwise mode of one cavity and kept fixed for both probe propagation directions. For forward propagation, the probe excites the counterclockwise mode of the adjacent cavity coupled to the strongly driven clockwise mode. Near the quantum critical point, the resulting strong coupling between the lower polariton and the adjacent cavity mode induces Autler-Townes (AT) splitting, enabling nearly perfect forward-direction transmission. In contrast, for backward propagation, the probe couples to the oppositely propagating mode without the same pump-enhanced optomechanical interaction, so that the AT effect is absent and the resonant probe is strongly absorbed. By tuning the incident-light frequency to the AT-split resonances, the transmission and absorption directions can be reversed, realizing reconfigurable optical nonreciprocity. Moreover, the operating frequency can be continuously tuned by varying the effective polariton-cavity coupling, which shifts the AT-split resonances. A tuning range exceeding 25 times the optical-cavity linewidth can be achieved. Numerical results agree well with the derived analytical frequency-matching conditions. This work provides a feasible theoretical strategy for the design of tunable nonreciprocal integrated photonic devices.
