Evaluation of zero-threshold optical gain in quantum dots based on size-controlled electron doping
Phys. Rev. B 111, 235302 – Published 12 June, 2025
DOI: https://doi.org/10.1103/mp9t-wfq7
Abstract
The multiexciton optical gain that stems from the multiple degeneracies of quantum dot (QD) band-edge states, along with the rapid multiexciton Auger recombination, results in a high lasing threshold for colloidal QD lasers, limiting their practical applications. In this article, we propose an approach to achieving a “zero-threshold” optical gain by controlling doping concentration via the QD size. By using , HgSe, and HgS QDs, zero-threshold optical gain was achieved across most wavelengths in the near-infrared and short-wave infrared regions. We established kinetic equations to describe a coupled QD-light-field system, which consists of QDs with varying doping concentrations. Based on this, we calculated the lasing thresholds for the three types of QDs with specific diameters. The results show that by significantly suppressing Auger recombination with the core/alloy/shell structure, pulsed lasing with an average QD occupancy threshold of approximately 0.17, and continuous-wave lasing with a threshold pump intensity of approximately can be achieved. This work presents an air-stable approach to realize “zero-threshold” optical gain and develops a theoretical model to confirm the feasibility of this approach.
