[演講公告]12/24(三)10:30～11:30 :DR. YA-LUN HO專題演講
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Ultrathin Photonic Membrane for 2D Material Light–Matter Interaction
Dr. Ya-Lun HO
Research Center for Electronic and Optical Materials National Institute for Materials Science (NIMS), Japan
12/24(三)10:30～11:30 R546, Engineering Building 5, NYCU (GuanFu Campus) 工程五館5樓546室
※Host : Prof. Guo-En Chang 張國恩教授 (Department of Microelectronics)
Abstract:
Atomic-layer and two-dimensional (2D) materials show great promise for controlling light–matter interactions at the atomic scale. However, their ultrathin geometry limits the interaction volume and reduces optical coupling. To fully realize their potential, photonic structures that concentrate light into atomic-scale regions with minimal loss are required. Here, an ultrathin freestanding photonic membrane tailored for integrating atomic-layer and 2D materials is introduced. Owing to its substrate-free geometry, the membrane provides strong field confinement, restores out-of-plane symmetry, and suppresses radiative leakage. The design also enables Å-level tuning of high-Q resonances, where even a single ALD cycle produces a clearly measurable shift, demonstrating sensitivity to atomic-scale dielectric thickness variations.
Due to the strong field confinement and substrate-free geometry, the membrane effectively serves as a platform for transition metal dichalcogenide (TMD) monolayers such as WS2, WSe2, and MoS2, enabling their excitonic and nonlinear responses to couple efficiently to the membrane resonances. The membrane supports quasi-bound states in the continuum (quasi-BICs) that confine light around the monolayer and enhance exciton–photon coupling, resulting in clear increases in photoluminescence and second-harmonic generation (SHG) across a large area. The stronger SHG further enables polarization-resolved mapping of crystal orientation and grain boundaries. SHG spectroscopy also reveals several narrow peaks associated with different quasi-BIC modes, confirming resonant nonlinear enhancement on this freestanding membrane and demonstrating Å-level resonance engineering and large-area uniform enhancement—opening pathways toward advanced 2D material nanophotonic, quantum, and nonlinear photonic devices.
