Slow light using semiconductor quantum dots

Abstract

A variable semiconductor optical buffer based on the electromagnetically induced transparency in a quantum dot waveguide is theoretically investigated with feasible parameters for applications to a 40 Gbps optical network. We show the refractive index and absorption spectra of the quantum dot waveguide at various pump levels, which exhibit an optimal pump power for maximum slow-down factor, in agreement with the previous experimental observation using a Pr-doped solid. The group velocity slow-down factor is theoretically analysed as a function of the pump intensity at different broadened linewidths. Inhomogeneous broadening in self-assembled quantum dots degrades the slowdown factor. In order to reduce the inhomogeneous broadening effects, we propose to use a resonant microcavity structure with quantum dots embedded in the active layer to enhance the slow-down factor.

Optical properties and optimization of electromagnetically induced transparency in strained InAs/GaAs quantum dot structures

“…28 EIT effects in quantum dots and wells have mostly been studied using models that are rooted in atomic physics assuming an archetypical EIT configuration in an ideal medium. 3,[6][7][8] These models truncate the number of active levels in the system to consider only the three levels being addressed by the laser fields. The generic EIT setup relies on a coupling and a probe laser driving separate transitions ͑see Fig.…”

“…Apart from Refs. 4 and 5 that focus on the many-body aspects of EIT operation most theoretical investigations of EIT induced slow light [6][7][8][9] have been based on simple quantum dot models that do not take into account important contributions from, e.g., biaxial strain.…”

Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules

“…With unique advantages, such as high nonlinear optical susceptibility, large electric-dipole moments of intersubband transitions, and great flexibility in designing devices [36][37][38], SQD system has wide applications in the fields of quantum optics and quantum information [39][40][41][42][43][44][45][46][47][48]. For example, the electromagnetically induced transparency (EIT) and the propagation of slow light have been realized in the SQD medium [43].…”

“…(i) The QDM medium studied here has widely adjustable parameters. For example, the transition energies and dipole moments of QDMs can be manipulated well by accurately tailoring their shapes and sizes [36][37][38]. However, such property can hardly be found in the atomic medium.…”

Reducing the impact of inhomogeneous broadening on quantum dot based electromagnetically induced transparency

“…1 The result has since then given rise to a number of impressive experiments based on EIT. 2 Quantum dots ͑QDs͒ are excellent candidates for EIT in semiconductor material due to their quantized energy levels and relatively low dephasing rates, 3 as well as the possibility for monolithic integration. In order to obtain a significant slowdown, it is necessary to interact with an ensemble of QDs.…”