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Register a new userSuppression of off-resonant cavity feeding through quasi-resonant pumping in a strongly coupled cavity-quantum dot system
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We compare the photoluminescence spectrum of an indium arsenide (InAs) quantum dot (QD) that is strongly coupled to a photonic crystal cavity under above band excitation (ABE) and quasi-resonant excitation (QRE). We show that off-resonant cavity feeding, which manifests itself in a bare cavity emission peak at the strong coupling point, is suppressed by as much as 40% under QRE relative to ABE. We attribute this suppression to a reduced probability of QD charging because electrons and holes are created in pairs inside the QD. We investigate the pump power dependence of the cavity feeding and show that, below saturation, the ratio of the bare cavity emission to polariton emission for ABE is independent of pump power, while for QRE there is linear pump power dependence. These results suggest that the biexciton plays an important role in cavity feeding for QRE.
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We present a medium-dependent quantum optics approach to describe the influence of electron-acoustic phonon coupling on the emission spectra of a strongly coupled quantum-dot cavity system. Using a canonical Hamiltonian for light quantization and a photon Green function formalism, phonons are included to all orders through the dot polarizability function obtained within the independent Boson model. We derive simple user-friendly analytical expressions for the linear quantum light spectrum, including the influence from both exciton and cavity-emission decay channels. In the regime of semiconductor cavity-QED, we study cavity emission for various exciton-cavity detunings and demonstrate rich spectral asymmetries as well as cavity-mode suppression and enhancement effects. Our technique is nonperturbative, and non-Markovian, and can be applied to study photon emission from a wide range of semiconductor quantum dot structures, including waveguides and coupled cavity arrays. We compare our theory directly to recent and apparently puzzling experimental data for a single site-controlled quantum dot in a photonic crystal cavity and show good agreement as a function of cavity-dot detuning and as a function of temperature.
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Recent experiments have demonstrated that for a quantum dot in an optical resonator off-resonant cavity mode emission can occur even for detunings of the order of 10 meV. We show that Coulomb mediated Auger processes based on additional carriers in delocalized states can facilitate this far off-resonant emission. Using a novel theoretical approach for a non-perturbative treatment of the Auger-assisted quantum-dot carrier recombination, we present numerical calculations of the far off-resonant cavity feeding rate and cavity mean photon number confirming efficient coupling at higher densities of carriers in the delocalized states. In comparison to fast Auger-like intraband scattering processes, we find a reduced overall efficiency of Coulomb-mediated interband transitions due the required electron-hole correlations for the recombination processes.
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