Dark-State Luminescence of Macroatoms at the Near Field

Abstract

We theoretically analyze the optical near-field response of a semiconductor macroatom induced by local monolayer fluctuations in the thickness of a semiconductor quantum well, where the large active volume results in a strong enhancement of the light-matter coupling. We find that in the near-field regime bright and dark excitonic states become mixed, opening new channels for the coupling to the electromagnetic field. As a consequence, ultranarrow luminescence lines appear in the simulated two-photon experiments, corresponding to very long lived excitonic states, which undergo Stark shift and Rabi splitting at relatively small field intensities.

Optical near-field mapping of bright and dark quantum dot states

“…The essentials of these findings are expected to prevail for dot confinements with lower symmetry [17].…”

“…with Γ0 the usual Wigner-Weisskopf decay rate, M0x and M xb the optical far-field matrix elements, which are obtained by integrating the elements (7) over the entire space [17], and Γ ph accounting for additional phonon scatterings [22] described in Lindblad form. The steady-state solutions, which results from the interplay of excitation and relaxation, and the luminescence spectra are finally obtained from Eq.…”

“…Throughout we assume a cw excitation with a single frequency ω. The coherent time evolution is then given by the master equation [15,17] …”

Near‐field control of the light emission properties of a symmetric semiconductor quantum dot

“…As pointed out in Ref. [16], this is a quite reasonable assumption since the photons can be emitted into any solid-angle direction, and the slightly modified photon density of states in the presence of the SNOM tip is not expected to be of great importance. Within these assumptions, recently [8] it has been shown that the nearfield spectrally resolved PL signal collected by the tip can be expressed as…”

“…The most striking manifestation of these effects is the breaking of the usual optical selection rules and the possibility to excite dark states whose optical excitation is forbidden by symmetry in the far field. Spatial maps of dark states in semiconductor nanostructures were simulated for high-resolution SNOM in absorption and two-photon experiments [7,9,[14][15][16]. Moreover, dark states are not able to emit light in the far-field, for they generate only fields with high in-plane wavevectors corresponding to evanescent waves.…”