• Figueroba, Alberto
• Christodoulou, Sotirios
• Dalmases, Mariona
• Itskos, Grigorios
• Konstantatos, Gerasimos
• Ramiro, Iñigo
• Othonos, Andreas
• Özdemir, Onur

Abstract

Materials with optical gain in the infrared are of paramount importance for optical communications, medical diagnostics, and silicon photonics. The current technology is based either on costly III-V semiconductors that are not monolithic to silicon CMOS technology or Er-doped fiber technology that does not make use of the full fiber transparency window. Colloidal quantum dots (CQDs) offer a unique opportunity as an optical gain medium in view of their tunable bandgap, solution processability, and CMOS compatibility. The 8-fold degeneracy of infrared CQDs based on Pb-chalcogenides has hindered the demonstration of low-threshold optical gain and lasing, at room temperature. We demonstrate room-temperature, infrared, size-tunable, band-edge stimulated emission with a line width of ∼14 meV. Leveraging robust electronic doping and charge-exciton interactions in PbS CQD thin films, we reach a gain threshold at the single exciton regime representing a 4-fold reduction from the theoretical limit of an 8-fold degenerate system, with a net modal gain in excess of 100 cm-1.

Topics

• impedance spectroscopy
• thin film
• Silicon
• quantum dot
• III-V semiconductor