Radiative decay of optically excited coherent plasmons in a two-dimensional electron gas

Abstract

We report on the observation of coherent submillimeter-wave emission from optically excited plasmons in a two-dimensional electron gas. Phase-synchronous plasma oscillations are induced by femtosecond optical pulses generating electron–hole pairs in the accumulation channel of an AlGaAs/GaAs heterostructure. The radiative decay of the grating-coupled plasmons is traced in time by terahertz-emission spectroscopy. An analysis of the data suggests that ultrafast thermalization and current surges are the plasmon-driving mechanism.