Photonic crystal reflex klystron using cold cathode

In this paper, we report a photonic crystal reflex klystron which can potentially radiate at submillimeter wave when the proper current density(∼kA/cm ) of electron beam is supplied. Using the property of photonic band gap, we are able to design photonic crystal resonator in which a high order TM_mno mode can be stably supported and coupled to an external system without distortion of the high order resonance mode, where the output power can be increased by m×n compared with conventional reflex klystron at the same frequency.