Light-Enabled Nano-Systems

Ⅳ: Coherent Control of Dark Excitons

A double-edged sword in two-dimensional material science and technology is optically forbidden dark exciton. On the one hand, it is fascinating for condensed matter physics, quantum information processing, and optoelectronics due to its long lifetime. On the other hand, it is notorious for being optically inaccessible from both excitation and detection standpoints. Here, we provide an efficient and low-loss solution to the dilemma by reintroducing photonic bound states in the continuum (BICs) to manipulate dark excitons in the momentum space. The BICs could be an intriguing photonic platform to reshape light-matter interactions in the nearby quantum materials.

→ Nature Communications (2022)

Ⅲ: Universal AI for Ubiquitous Resonances

Resonance is ubiquitous in optics, physics, and mechanics. While one can use numerical simulations to sweep geometric and material parameters of structures, these simulations usually require a considerably long time and substantial computational resources. We developed a universal deep-learning strategy to design high-finesse resonances with ultrasharp spectral features. Applying them to photonic bound states in the continuum (BICs), we decomposed a spectrum into a relatively smooth background and multiple spectral extremes, followed by an adaptive data acquisition and a regulation with a classical Fano resonance equation.

→ Laser & Photonics Rev. (2022)

Ⅱ: Atomic-scale Magneto-chiral Effect

The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of a strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral anisotropy reaching a value of ~4%.

→ Nature Communications (2021)

Ⅰ: Monolithic Full-Stokes Polarimeter

The ability to detect the full-Stokes polarization of light is vital for a variety of applications that often require complex and bulky optical systems. Here, we report an on-chip polarimeter comprising four metasurface-integrated graphene–silicon photodetectors. The geometric chirality and anisotropy of the metasurfaces result in circular and linear polarization-resolved photoresponses, from which the full-Stokes parameters, including the intensity, orientation, and ellipticity of arbitrarily polarized incident infrared light (1550 nm), can be obtained. The design presents an ultracompact architecture while excluding the standard bulky optical components and structural redundancy.

→ ACS Nano (2020)