Nano Optics and Plasmonics
Nano optics or nanophotonics explores of the behavior of light at the nanometer scale. Dielectric-based nanophotonics, especially silicon nanophotonics, has manifested a wide range of novel phenomena and applications. However, it still suffers the conventional diffraction limit. Recently, metal-based nano plasmonics has emerged as a new research paradigm in nano optics, which allows us to break the fundamental diffraction limit and confine light into the deep subwavelength scale. Meanwhile, the field intensity can be significantly enhanced due to the strong confinement. We are interested in the nonlinear and quantum optical properties and novel optical devices based on the plasmonic platform.
Nano Materials and Metamaterials
The emerging field of electromagnetic metamaterials offers an entirely new route to design material properties at will. Different from natural materials, the physical properties of metamaterials are not primarily dependent on the chemical constituents, but rather on the internal, specific structures of the building blocks of metamaterials. These building blocks function as artificial “atoms” and “molecules”, in analogy to those in natural materials. Through regulated interactions with electromagnetic waves, metamaterials can produce remarkable properties that are difficult or impossible to find in naturally occurring or chemically synthesized materials. We are investigating 3D and 2D metamaterials with appropriate architecture design at deep subwavelength scale, and studying the extraordinary wave propagation behavior originating from the symmetry, topology, anisotropy, chirality and nonlinearity of metamaterials.
Ultrafast Control of Magnetism
Recent research has shown that ultrafast lasers can control magnetization in certain magnetic materials without any external magnetic fields, potentially leading to high-rate data storage for the Big Data era. However, the underlying mechanisms remain elusive. We have been developing unique techniques, such as pump-probe spectroscopy, transient MOKE, and a multiphysics simulation framework, to better understand and manipulate magnetization using purely optical methods. Furthermore, combing all-optical switching with nano plasmonics, we may realize spin manipulation at the nano and even quantum level.
Nano Devices and Applications
Plasmonics simultaneously combines the fast dynamics of photonic processes and the capability of tight optical confinement well beyond the diffraction limit. It is considered as one of the most candidates for the next generation of ultra-fast and ultra-compact photonic circuits. We have demonstrated important nano optical devices including the plasmonic generator, lens, waveguide bend, etc. In addition, we have been working on other aspects of plasmonics applications ranging from biomedical sensing, near-field microscopy and spectroscopy to energy harvesting. We are also interested in the hybridization of plasmonics and nanoelectronics, which may allow for simultaneous transport of light and electric information, and active control of both of them.
Interfacing Photonics with Artificial Intelligence
Our group and a few others have pioneered to apply artificial intelligence, including deep learning, in photonic design tasks. In sharp contrast with the conventional physics- guided or rule-based approaches, the unique advantages of deep learning lie in its nature of data-driven methodology that allows the deep learning model to automatically discover the highly nonlinear and non-intuitive structure-property relationship from a huge amount of data. Therefore, it offers an alternative yet powerful tool to rationally design various photonic structures, devices, and systems with on-demand spectral, temporal, angular, nonlinear, and quantum responses. By interfacing photonics with artificial intelligence, we can push the capacity of all-optical computing, communications, encryption, and data storage to an unprecedented level.