Measuring Terahertz Radiation in Laboratory Simulations of Astrophysical Plasma Jets with Field-Effect Transistors

Experiments simulating astrophysical plasma jets at Caltech have densities of 10²¹ to 10²² m^-3, so the electron plasma frequency falls in the low terahertz regime. Because the upper hybrid frequency is dominated by the electron plasma frequency in this experiment, a strong terahertz radiation emission is expected from electromagnetic wave excitation at the upper hybrid resonance layer. However, measurement of this radiation is challenging because of the “terahertz gap” in detection technology, such that there is a dearth of suitable detectors.

Field-effect transistors (FETs) have been shown [1] to develop an internal plasma wave resonance when illuminated by terahertz electromagnetic radiation. Nonlinearity associated with this resonance produces a small tunable DC response which can be used to produce a relatively simple detector of terahertz radiation. We are constructing such a device from a commercially available FET and will attempt measurement of plasma radiation in this frequency regime from the jet experiment.



[1] M. Dyakonov and M. Shur, IEEE Trans. Electron Devices, 43, 380 (1996)