Overcoming optical loss in a polariton system with synthetic complex frequency waves
A collaborative research team co-led by Professor Shuang Zhang, the Interim Head of the Department of Physics, The University of Hong Kong (HKU), along with Professor Qing DAI from National Center for Nanoscience and Technology, ...
Their findings, recently published in Nature Materials, propose a synthetic complex frequency wave (CFW) approach to address optical loss in polariton propagation.
These findings offer practical solutions, such as more efficient light-based devices for faster and more compact data storage and processing in devices such as computer chips and data storage devices, and improved accuracy in sensors, imaging techniques, and security systems.
Surface plasmon polaritons and phonon polaritons offer advantages such as efficient energy storage, local field enhancement, and high sensitivities, benefitting from their ability to confine light at small scales. However, their practical applications are hindered by the issue of ohmic loss, which causes energy dissipation when interacting with natural materials.
Over the past three decades, this limitation has impeded progress in nanophotonics for sensing, superimaging, and nanophotonic circuits. Overcoming ohmic loss would significantly enhance device performance, enabling advancement in sensing technology, high-resolution imaging, and advanced nanophotonic circuits.
Figure 1. Schematic of polariton propagations under real frequency and synthesized complex frequency excitation. While polariton waves at real frequencies have limited propagation distance, combining propagation waves from different real frequencies based on complex frequencies of incidence can achieve nearly lossless propagation. Credit: Nature Materials (2024). DOI: 10.1038/s41563-023-01787-8
Figure 2. 1D Polariton propagation (from left to right) using hBN film operating at optical frequency. (a) Real frequency images show obvious decay field profile at propagation direction. (b) Complex frequency measurements provide almost non-dissipative propagation behavior. Credit: Nature Materials (2024). DOI: 10.1038/s41563-023-01787-8
Figure 3. Hyperbolic phonon polariton and elliptical phonon polariton propagation on α-MoO3 film. (a) AFM of an antenna placed on the α-MoO3 film. (b) Real frequency measurements of hyperbolic polariton in different real frequencies. (c) Complex frequency measurement provides an ultra-long distance propagation behavior. (d) AFM of two different spaced gold antennas. (e) The amplitude and real part of the measurements at real frequency f=990cm-1. (f) The amplitude and real part of measurements at complex frequency f=(990-2i)cm-1. Credit: Nature Materials (2024). DOI: 10.1038/s41563-023-01787-8