Observation of grating diffraction radiation at the KEK LUCX facility.

The development of linac-based narrow-band THz sources with sub-picosecond, [Formula: see text]-level radiation pulses is in demand from the scientific community. Intrinsically monochromatic emitters such as coherent Smith-Purcell radiation sources appear as natural candidates. However, the lack of broad spectral tunability continues to stimulate active research in this field.