Amplified Spontaneous Emission and Lasing from Zn-Processed AgIn₅S₈ Core/Shell Quantum Dots

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• I-III-VI ternary quantum dots (QDs) are promising alternatives to toxic II-VI QDs.
• Low fluorescence efficiency limits their use in optical gain media for microlasers.

Purpose of the Study:

• To demonstrate amplified spontaneous emission (ASE) and lasing from Zn-processed AgIn5S8 (AIS) colloidal QDs.
• To improve the optical properties of AIS QDs for photonic applications.

Main Methods:

• Passivation treatment of AIS QDs with Zn.
• Fabrication of AIS/ZnS core/shell QD films.
• Optical pumping (one- and two-photon) to achieve ASE.
• Fabrication of whispering-gallery-mode microlasers.

Main Results:

• A 3.4-fold enhancement in fluorescence quantum efficiency was achieved.
• A 30% increase in two-photon absorption cross-section was observed.
• Low ASE thresholds (∼84.5 μJ/cm2 for one-photon, 3.1 mJ/cm2 for two-photon) were obtained.
• A microlaser with a lasing threshold of ∼233 μJ/cm2 was demonstrated.

Conclusions:

• Passivated AIS QDs exhibit excellent optical gain properties.
• These QDs are comparable to Cd-based QDs in performance.
• AIS QDs show potential as efficient optical gain media for photonic devices.