Predictive wavelength tailoring of uniform GaSb-based quantum dots for emission at 1.55 um

Abstract

A detailed study of emission wavelength tailoring of GaSb-based QDs formed by InGaSb-filling of droplet-etched nanoholes in AlGaSb is presented. The study shows that the emission wavelength can be modified from 1.48 um to the center of the telecom C-band at 1.55 mm by independently varying the QD composition and size. More specifically, the optical transition energy shifts linearly as a function of In-content of the QD material at a rate of -4.4 meV/In-percentage, and with the number of monolayers (ML) of material used for filling the nanoholes, at -2.0 meV/ML. These experimentally observed energy shifts are well predicted by simulations yielding rates of -4.3 meV/In-percentage and -2.1 meV/ML, respectively. For the simulation, a uniform In composition, low intermixing, and microscopically measured QD geometry is considered. Additionally, excellent ensemble QD uniformity, with unprecedented inhomogeneous broadening well-below 7 meV across all samples is demonstrated. Finally, photoluminescence of single-QDs reveals narrow excitonic emission lines of 13.8+/-6.7 ueV and low fine-structure splitting values reaching <10 ueV. These results identify GaSb-based LDE QDs as a tunable telecom platform for scaling quantum-photonic applications over long-haul optical fiber networks.