RESEARCH

The discovery of new materials or new technologies designates a new era, for instance, the Bronze Age and the Iron Age. At the turn of this century, a new technology emerged to design materials by artificially arranging structures at a subwavelength scale. Instead of obtaining material properties by chemical compositions, this new technology relies more on geometrical designs that are readily achievable through modern semiconductor fabrication facilities. As a result, this technology has considerably extended materials space beyond the scope of natural materials, and it is named metamaterial (from the Greek word μετά meta, meaning “beyond”). Exploring these areas is of great importance for both fundamental physics and practical applications. We are particularly interested in this exciting frontier in optics and photonics. For example, we have applied a thin metamaterial to enable augmented reality on contact lenses towards dramatically reduced device footprint. With optical functionalities by design, it is arguably safe to say that photonics enters a new era named “metaphotonics.”

Nature Comm. 13 (2022), ACS Photonics 6 (2019),  Nano Letters 17 (2017), Nature Comm. 8 (2017), Advanced Materials 27 (2015), Advanced Materials 26 (2014), Nano Letters 14 (2014)

For a scientist, nothing is more exciting than contributing to human knowledge by finding and breaking a limit. One such limit in optics is the “diffraction limit,” which indicates that it is impossible to distinguish two objects with a distance smaller than half of the optical wavelength. Excluding super-resolution microscopy playing with the time, a possible solution is to use plasmonics on the surfaces of metals (typically gold and silver) by harvesting the near-field momenta. Unfortunately, like eating fish while dealing with the fishbone, the plasmonics needs to deal with the Ohmic loss of metals. Many applications temp to live with it, and they look at the bright side that the loss is not necessarily harmful. We are optimistic about plasmonics for recognizing the conventional role of a plasmonic metal as a conductor to conduct electric signals. And hence, the plasmonic device can simultaneously have dual optical and electrical functionalities, which is promising in nanoscale plasmonic circuitry that potentially extends Moore’s law governing modern electronics based on semiconductors. We have found some niche applications in nonlinear optics, plasmoelectronics, desalination, and energy conversion.

Desalination 532 (2022), Advanced Composites and Hybrid Materials (2022), Laser & Pho. Rev. 11 (2017), Nano Letters 16 (2016), Nature Materials 14 (2015), Nature Comm. 5 (2014)

The strong in-plane bonding and relatively weak out-of-plane van der Waals forces have enabled exfoliating layered 2D materials down to only one or a few atoms thick. At this atomic scale, many exotic physics and phenomena emerge. We are interested in the fundamental study of photon-matter interactions and related quantum information science in 2D materials. A critical factor in advancing this research field is to modulate material properties beyond what they traditionally offer. Rather than modifying 2D materials directly, we surround them with an engineered electromagnetic environment or meta-environment. We investigate local and topological effects in both weak and strong coupling regimes. For instance, we utilized photonic crystals that support bound states in the continuum (BICs) to demonstrate coherent, directional emission from dark excitons otherwise optically forbidden. We also translate and explore 2D materials for future technologies with a small device scale, fast operating speed, and low energy consumption.  

Nature Comm. 13 (2022), Nature Comm. 12 (2021), Nanophotonics 10 (2021), ACS Nano 14 (2020), Nano Letters 20 (2020), Advances in Optics and Photonics 8 (2016), ACS Photonics 3 (2016)