• T. Denis, K.-J. Boller, P.J.M. van der Slot
  Mesa+, Enschede

Compact, slow-wave, low energy electron beam radiation sources, like Cerenkov free-electron lasers (FELs), emit high power microwaves. However, they seriously degrade in output power, when scaled towards the THz range (0.1-10 THz). This prevents industry from applying THz radiation, although it would allow many new applications, like chemical selective security surveillance. The photonic free-electron laser (pFEL) is a promising concept for a handheld, tunable and Watt-level THz laser. In a pFEL several electron beams stream through a photonic crystal (PhC) leading to the emission of coherent Cerenkov radiation. The beams emit phase-locked due to the transverse scattering inside the PhC, which allows increasing the output power by increasing the number of beams streaming through the PhC. Therefore, scaling the pFEL’s operating frequency towards THz frequencies can be done without loss in output power. Furthermore, compact, low energy electron sources (< 15 keV) can drive the laser, due to the strong deceleration of the light by PhC’s. As a proof of principle, we developed the setup for a pFEL operating at 20 GHz to study the interaction between a single electron beam and the PhC.