Optically driven field emission array for THz amplifiers

We present the first steps for the validation of a field emission array (FEA) adapted to the modulation of electron beams at THz frequencies. This specific cathode relies on the coupling of an infrared dual-frequency laser (Deltaf~1THz) with a field emitter array composed of Multi-Wall Carbon Nanotubes. Thanks to the pre-modulation of the electronic beam, increased powers are expected for the Traveling Wave Tube (TWT) configuration. To maximize the coupling efficiency, a 1D metallic grating is used to localized and magnify the incident energy laser beam around each field emitter. Numerical optimization as well as the experimental validation of the grating performances are presented.