Electrodynamic modeling of strong coupling between a metasurface and intersubband transitions in quantum wells

摘要

Strong light-matter coupling has recently been demonstrated in sub-wavelengthvolumes by coupling engineered optical transitions in semiconductorheterostructures (e.g., quantum wells) to metasurface resonances via nearfields. It has also been shown that different resonator shapes may lead todifferent Rabi splittings, though this has not yet been well explained. In thispaper, our aim is to understand the correlation between resonator shape andRabi splitting, and in particular determine and quantify the physicalparameters that affect strong coupling by developing an equivalent circuitnetwork model whose elements describe energy and dissipation. Because of thesubwavelength dimension of each metasurface element, we resort to thequasi-static (electrostatic) description of the near-field and hence define anequivalent capacitance associated to each dipolar element of a flatmetasurface, and we show that this is also able to accurately model thephenomenology involved in strong coupling between the metasurface and theintersubband transitions in quantum wells. We show that the spectral propertiesand stored energy of a metasurface/quantum-well system obtained using our modelare in good agreement with both full-wave simulation and experimental results.We then analyze metasurfaces made of three different resonator geometries andobserve that the magnitude of the Rabi splitting increases with the resonatorcapacitance in agreement with our theory, providing a phenomenologicalexplanation for the resonator shape dependence of the strong coupling process.