Optical Transmission Performance of Photonic Crystal Fiber Doped with Near-Infrared PbS Quantum Dots

We fabricated a PbS quantum-dot-doped photonic crystal fiber (QD-PCF) working in the near-infrared range of 1400-1650 nm and measured its absorption of 980 nm pump light and 1550 nm signal light. Upon the excitation of 980 nm pump light, we acquired the photoluminescence (PL) spectrum of the QD-PCF and determined the doping concentration (mass fraction) and fiber length that maximized the PL intensity at the central wavelength of 1550 nm. The PL intensity of the QD-PCF far exceeded that of the usual single-core quantum-dot-doped fiber (QDF), appearing multiple intensity peaks spacing a short distance. The intensities of these peaks were related to the doping concentration. Comparing the QD-PCF with the un-doped PCF, the bandgap was not found to be changed by quantum-dot doping. The threshold and saturated pump powers of the QD-PCF were also measured. The threshold pump power approximated that of the QDF, but the saturated pump power exceeded that of the QDF, owing to the larger fiber section and higher doping concentration in the QD-PCF.