Abstract
Calculations and experimental data are reported on the optical coupling to the Bernstein modes of a two-dimensional electron gas (2DEG) in a perpendicular magnetic field using an overlaid grating coupler. The Bernstein modes are harmonics of the cyclotron resonance and are observed indirectly through their interaction with the 2DEG magnetoplasmon. The optical response of a grating-heterojunction structure is calculated using a modal expansion technique, with the Bernstein modes included semiclassically through non-local corrections to the 2DEG conductivity tensor. Dispersion curves deduced from the calculated spectra show the expected anticrossing behaviour at magnetic fields for which the Bernstein and magnetoplasmon modes have similar frequencies. This calculated dispersion behaviour is in excellent agreement with experimental data on a GaAs/AlGaAs heterojunction sample, underlining the importance of using the full electromagnetic response of the structure, including the periodic screening effects of the coupling grating, in comparisons between theory and experiment. The strength of the coupling to the Bernstein modes is also extremely well modelled.
Published Version
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