Giant enhancement of interlayer electric field at terahertz plasma resonance in an asymmetric bilayer of two-dimensional electron strips

We study theoretically the terahertz (THz) response of a bilayer of two-dimensional electron strips modeling the double-quantum-well electron channel of a grid-gated field-effect transistor, in which strong THz photoresponse was recently observed. We have shown that the mixing between optical and acoustic plasmons hugely increases at the anticrossing of optical-like and acoustic-like plasma resonances excited by incoming THz radiation in such a bilayer. As a result, the amplitude of interlayer THz electric field also increases dramatically in the anticrossing regime. This strong interlayer THz electric field must strongly enhance the interlayer electron tunneling which, in turn, may contribute to the physical mechanism underlying the strong THz photoresponse observed in recent experiments.