Ultra-fast terahertz Schottky diode detector

An ultra-fast terahertz Schottky diode detector with a response time less than 20 ps is presented in the paper. The detector allowed us to measure not only the duration of the light pulses in the Novosibirsk terahertz free electron laser (NovoFEL) but also the time structure of these pulses in unstable regimes. This is important for determining the NovoFEL impulse power and for studying and suppressing its different instabilities.