Mn(II) Ions Assisted Near-Infrared Single-Mode Lasing from an Individual Mn-Doped CdS Nanobelts

Tunable single-mode lasers are attractive for their potential applications in signal processing, optical communication, and displays. Here we present the Mn(II) ions assisted single-mode lasing occurring at near-infrared (NIR) band instead of the green emission band of CdS nanobelts (NBs) for the first time. Successful substation of Mn(II) ions at the tetrahedral Cd²⁺ cites in the CdS matrix were confirmed by EPR. Light Mn(II) doping (≤1%) in CdS belts not only red-shifted the Raman modes but also increased crystallinity compared to pure CdS NBs due to strong excitons-phonon couplings. Up to 3 µJ · cm^-2 pumping fluence of ns laser, lightly doped CdS:Mn NBs show two photoluminescence (PL) emissions. First emission centered at 514.2 nm (green) corresponds to band-edge of CdS and an in-gap emission centered at 771.4 nm (NIR) corresponds to Mn(II) ions aggregates. After using intense excitation pulse, these NBs exhibited lasing at 791.4 nm with the lowest laser thresholds at 4.2 µJ · cm^-2 in the CdS system. This lasing action is further confirmed by lifetime kinetics. The results indicated that the lasing in these NBs involves the localised excitons magnetic polarons and Farby-Perot (F-P) optical resonant processes at room temperature.