Magneto-optical Terahertz emission from plasmons in parabolic quantum wells

We report far-infrared emission from coupled plasmons in a parabolically gr aded AlGaAs/GaAs single quantum well driven by an inplane electric field. A magnetic field tilted at different angles with respect to the sample's gro wth axis is applied to couple the intersubband resonance to the cyclotron r esonance. The measured mode dispersion shows an anticrossing as calculated in a simple centre of mass picture and confirms the Kohn theorem. For measu red optical powers up to 10(-7) W temperatures of the hot electron gas up t o 70 K are found. At inplane magnetic fields a small satellite peak indicat es deviations from ideal parabolicity.