Induced Transparency by Intersubband Plasmon Coupling in a Quantum Well

We study coupling of two intersubband plasmons associated with dipole-allowed cascading transitions in a quantum well. We show that the coupling can lead to the disappearance of the lower-energy resonance accompanied by an anticrossing behavior. Such coupling induced anomalies are of collective and resonant nature and provide the first example of Coulomb interaction induced transparency. Our numerical results from a microscopic theory are confirmed by an analytical model.

Figure 1

Intersubband spectra of a GaAs quantum well. Different curves, offset for clarity, correspond to $E_{32}$ (upper subband separation at $\mathit{k}=0$) tuned from 20 to 80 meV with a 5 meV interval. Inset shows peak energy as a function of $E_{32}$. The open circle indicates where an induced transparency occurs at the lower-energy resonance. Parameter values used: $m_1=0.068m_e$, $m_2=0.073m_e$, $m_3=0.080m_e$; $d_{12}=-33.5\mathrm{e}Å$ and $d_{23}=-37.6\mathrm{e}Å$.

Figure 2

Absorbance associated with individual polarization components $P_{12}$ and $P_{23}$. The inset shows absorbance in linear-log scale: single-particle (SP) spectrum (dashed curve) consisting of two nearly degenerate transitions, Hartree-Fock (Full) result (solid curve) showing a narrowed and blue shifted single-resonance spectrum, and the Hartree (ISP) spectrum (long dashed curve).