Stimulated emission in a CuInS₂/ZnS core-shell quantum-dot-doped liquid-core optical fiber

We fabricated QD liquid-core optical fibers by doping C u I n S ₂/Z n S (CIS/ZnS) core/shell QDs with cladding times of 90 and 60 min, respectively, and compared and analyzed their emission properties with those of bare core C u I n S ₂ QDs. For CIS/ZnS core/shell QDs (with cladding time of 90 min) doped fibers, their emission transmits the longest distance in the fiber, and the emission intensity is approximately 4.73 times that of bare-core QD-doped fibers. Additionally, the fact that the full-width at half-maximum is narrowing and the spectral intensity is rapidly increasing superlinearly with excitation power indicates that stimulated emission happens in the fiber. The optical performance was compared and showed good agreement with a theoretical two-level system model for the QDs confined in an optical waveguide.