The potential of field effect cathode transferred-electron device (FECTED) oscillator based optronic applications is investigated theoretically and experimentally. The modeling relies on time-domain circuit simulation including a quasi-bidimensional hydrodynamic FECTED model. The work reported here is focused on a 33 GHz GaAs FECTED oscillator. The possibilities of an optical/mm-wave up-conversion; optical/RF mixing and optical injection-locking are demonstrated theoretically. FECTED devices and circuits have been realized. The feasibility of a simple FECTED oscillator based optical/mm-wave link is confirmed experimentally.