Photonics Research, Volume. 11, Issue 11, 1945(2023)
Broadband infinite-Q plasmons enable intense Smith–Purcell radiation
Fig. 1. Illustration of intense Smith–Purcell radiation from symmetry-protected BICs. By elaborately customizing the depth-modulated grating, the BICs are constructed from SSPs over a broad frequency range and are then employed to emit intense Smith–Purcell radiation. Compared with the conventional one, the radiation intensity of BIC-enhanced SPR is increased by several orders of magnitude.
Fig. 2. Formation of SSP-based BICs induced by the asymmetry of the depth-modulated grating. When the asymmetry parameter
Fig. 3. Validation of symmetry-protected BIC from SSPs. (a) Dispersions of symmetry-broken grating and plane wave with incident angle
Fig. 4. Broadband presence verification for symmetry-protected BIC. (a), (c) Dispersion relations of symmetry-broken gratings when
Fig. 5. Validation of intense Smith–Purcell radiation from SSP-based BIC. (a) Dispersions of symmetry-broken grating and 40-keV
Fig. 6. Broadband enhancement verification for intense Smith–Purcell radiation from SSP-based BICs. (a) Dispersion relations of symmetry-broken gratings and
Fig. 7. Demonstration for SSP-based BIC from ultrathin plasmonic metasurface. (a) Schematic drawing of the unit cell of the ultrathin plasmonic metasurface (periodic in
Fig. 8. Experimental setups and verification. (a), (b) Plasmonic antennas fabricated in the microwave band with
Fig. 9. Illustration and structural description of the plasmonic antenna. (a) Hybrid CPW-SSP plasmonic antenna. (b) Segment of CPW, where the inner conductor is narrow to wide for phase compensation. (c) Matching transition with gradient grooves and flaring ground. (d) Ultrathin plasmonic grating with modulated depths.
Fig. 10. Theoretical and experimental results of plasmonic antenna. (a), (b) Dispersion relations of ultrathin plasmonic metasurface when
Fig. 11. Dispersion curves of SSPs under different modulation periods. The dispersion curves and BIC distribution of SSPs with two, three, four, and five propagation periods within one modulation period are shown in (a), (b), (c), and (d), respectively. The solid black lines represent conventional SSPs, while the dashed red lines represent BIC modes resulting from resonant SSPs’ transformation.
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Zi-Wen Zhang, Chao-Hai Du, Yu-Lu Lei, Juan-Feng Zhu, Pu-Kun Liu, "Broadband infinite-Q plasmons enable intense Smith–Purcell radiation," Photonics Res. 11, 1945 (2023)
Category: Surface Optics and Plasmonics
Received: Jul. 5, 2023
Accepted: Sep. 1, 2023
Published Online: Nov. 3, 2023
The Author Email: Chao-Hai Du (duchaohai@pku.edu.cn)