Terahertz laser diode using field emitter arrays

High-power and broad-tunable terahertz wave generating source on chip, which has broad application prospects, remains an unachieved goal of researchers after decades of pursuing. Here, we propose a concept of terahertz laser diode, which is a dc-biased self-excited microelectronic laser oscillator using collectively modulated free electrons emitted by field-emitter-arrays as the active medium and using an inherent Fabry-Pérot interferometer formed by port reflections as the frequency selector. It is sub-millimeter to centimeter in size and can generate continuous-wave coherent terahertz radiation with several watts of power per square millimeter. Its frequency can be tuned to cover a wide terahertz band by changing the cathode-to-anode distance and the bias voltage. It has the potential to outperform the conventional free-electron or solid-state terahertz devices in terms of portability, tunability, and output power, signifying a promising class of tunable and high-power terahertz source on chip.