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  • Robust and efficient wireless power transfer using a switch-mode implementation of a nonlinear parity-time symmetric circuit NATURE ELECTRONICS Assawaworrarit, S., Fan, S. 2020
  • Dynamics for encircling an exceptions point in a nonlinear non-Hermitian system OPTICS LETTERS Wang, H., Assawaworrarit, S., Fan, S. 2019; 44 (3): 638–41

    Abstract

    We study the dynamics near an exceptional point in a nonlinear non-Hermitian system consisting of a pair of resonators. One of the resonators has a linear loss, and the other resonator has a saturable gain. We show that the system dynamics exhibit chiral characteristics. And moreover, unique to the nonlinear system, such dynamics allow one to adiabatically switch between bistable states at the same system parameter. Such bistable switching is potentially interesting in optical memory based on coupled laser systems.

    View details for DOI 10.1364/OL.44.000638

    View details for Web of Science ID 000457292400044

    View details for PubMedID 30702698

  • Robust wireless power transfer using a nonlinear parity-time-symmetric circuit NATURE Assawaworrarit, S., Yu, X., Fan, S. 2017; 546 (7658): 387-+

    Abstract

    Considerable progress in wireless power transfer has been made in the realm of non-radiative transfer, which employs magnetic-field coupling in the near field. A combination of circuit resonance and impedance transformation is often used to help to achieve efficient transfer of power over a predetermined distance of about the size of the resonators. The development of non-radiative wireless power transfer has paved the way towards real-world applications such as wireless powering of implantable medical devices and wireless charging of stationary electric vehicles. However, it remains a fundamental challenge to create a wireless power transfer system in which the transfer efficiency is robust against the variation of operating conditions. Here we propose theoretically and demonstrate experimentally that a parity-time-symmetric circuit incorporating a nonlinear gain saturation element provides robust wireless power transfer. Our results show that the transfer efficiency remains near unity over a distance variation of approximately one metre, without the need for any tuning. This is in contrast with conventional methods where high transfer efficiency can only be maintained by constantly tuning the frequency or the internal coupling parameters as the transfer distance or the relative orientation of the source and receiver units is varied. The use of a nonlinear parity-time-symmetric circuit should enable robust wireless power transfer to moving devices or vehicles.

    View details for PubMedID 28617463