Researchers develop compact superradiant Smith-Purcell device with an ultra-narrow and continuously tunable spectral linewidth

https://phys.org/news/2025-04-compact-superradiant-smith-purcell-device.html

"train of free electron radiation bunches passing over periodic grating... overcomes electron kinetic energy instability, coulomb effect, finite number of electron bunches worsening radiation linewidth, equipment's large size... ~0.3 THz pump-induced frequency, with radiation linewidth continuously tuned from 900 to 0.3 kHz... electron pre-bunching, electron-compression and harmonic-emission sections... on-chip electron acceleration for higher electron acceleration gradient... imaging, sensing, communication"