Modulation of Spin Angular Momentum of Emission in Symmetric 1D Plasmonic Crystals by Cathodoluminescence
Yuxin Yang, Izzah Machfuudzoh, Qiwen Tan, Takumi Sannomiya
TLDR
This paper shows how symmetric 1D plasmonic crystals can generate and dynamically modulate circularly polarized light using an electron beam.
Key contributions
- Symmetric 1D plasmonic crystals are shown to generate controllable circularly polarized light (CPL).
- Electron beam excitation in STEM coherently excites plasmonic modes, producing energy- and momentum-resolved CPL.
- Reveals CPL dispersion and spatial dependence at nanoscale, guiding manipulation and plasmonic device design.
- Demonstrates CPL generation efficiency modulation by varying electron beam excitation position.
Why it matters
This research overcomes limitations of traditional chiral systems by enabling CPL modulation in symmetric structures. It provides fundamental insights into light-matter interactions at the nanoscale, crucial for next-generation photonic technologies. The findings offer a new pathway for designing dynamically tunable plasmonic devices.
Original Abstract
The spin angular momentum (SAM) of light has become a cornerstone of numerous photonic applications, including optical communication and chiral photonics. Because SAM is inherently associated with circularly polarized light (CPL), the ability to modulate CPL in a controlled and efficient manner is essential not only for advancing fundamental studies of light-matter interactions but also for enabling next-generation photonic technologies. However, such modulation is commonly realized by structurally chiral systems, which inherently limits the feasibility of dynamic tuning. Here, we demonstrate that one-dimensional plasmonic crystals (1D PlCs), despite their structural symmetry, can serve as a platform for controllable CPL generation. By employing an electron beam in scanning transmission electron microscopy (STEM), we coherently excite transition radiation and emission from 1D PlC modes. Their interference produces energy- and momentum- (emission angle-) resolved CPL, which clearly reveals its dispersion and spatial dependence at the nanoscale, providing direct guidance for its manipulation and offering insights into the design of plasmonic devices including the phase information. Furthermore, interference with surface plasmon polariton scattering at the structural boundary enables the efficiency modulation of CPL generation via the excitation position along the terrace.
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