Abstract

We systematically investigate the Smith–Purcell radiation emitted by electrons moving along a metal-plate array. Neglecting absorption loss, we show that Smith–Purcell radiation can be enhanced by leaky resonances near bound states in the continuum. When absorption loss is considered, by changing the period of metal plates so that the resonant frequency increases from microwave to terahertz, the amplitude of the resonance-enhanced Smith–Purcell radiation is found to decline in low frequencies (${\lt}5\;{\rm THz} $) and then remain relatively stable in high frequencies (5–15 THz). Our results reveal that despite the absorption loss in the metal, leaky resonances can still substantially enhance Smith–Purcell radiation in microwave and terahertz.

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