| Colloidal PbSe quantum dot is a hot material of scientific research workers inrecent years just because it has unique electrical and optical properties comparedwith the corresponding bulk materials. For example, they have relatively broadabsorption spectrum, narrow emission spectrum, high photoluminescence quantumyield (PL QY) and well optical stability. What’s more, the absorption andphotoluminescence (PL) of QDs present strong size dependent properties due tothe quantum confinement effect. Among many types of QDs, PbSe QDs have beengaining increased attention because of PbSe’s large Bohr radius (about46nm),strong size confinement effect, and tunable emission range. In addition, in opticalfiber communication, the fiber has many advantages such as large capacity, smallfiber loss, small volume and good anti jamming performance; in the aspect ofoptical fiber sensing, the fiber has advantages of compact structure and highsensitivity. So the fiber attracted much attention. This paper combined PbSe QDsand fiber, and made into PbSe QDs liquid-core fiber successfully. Studied thespectral (we called the GSE spectra (guided spontaneous emission)) properties ofthe PL of PbSe QDs after transmitted through the fiber. Included the spectralproperties when the fiber parameters and the temperature changes. Under the threelevel system approximation, we established the theoretical model and obtained theevolution equation of the optical power in the fiber. The result is consistent withthe experimental data which provides certain theoretical support for the experiment.Finally, the temperature depended GSE properties were studies in detail. Theresearch has a certain application perspective in the aspect of fiber communications,fiber amplifiers and fiber sensors. Our main work is arranged as follows.1. a series of PbSe QDs with different size was synthesized using colloidalchemical synthesis method. The PL QY can reach to89%. The absorption (Abs) and photoluminescence (PL) spectra were recorded for different size QDs. Theband gap of PbSe QDs were approved to be size depended.2. the absorption and emission in the PbSe QDs can be approximated to be athree level system. The theory model was established through solving the rateequations and the power propagation equations in the fiber. Simulated theproperties of the spectra under the influence of fiber parameters, included the fiberlength, the fiber diameter, the doping concentration and the pump power. Moreimportantly, many influence factors were considered in our simulations. Such asnon-radiative transition (Auger recombination), luminescence efficiency of PbSeQDs and the mode leakage of the fiber and so on. F inally, our theoretical resultswere compared with the experimental data reported by Hreibi, et al. and wereproved to be a good practicability.3. PbSe QD-doped liquid-core fiber worked in the1.55μm communicationwindow was studied. The PbSe QD solution with diameter of4.5nm were filledinto hollow core fiber and sealed up seriously. After that, we designed theexperimental method, set up the light path and recorded the GSE spectra underdifferent fiber parameters, including fiber length, doping concentration and pumppower. In addition, we compared the influence of the two solvent to the propertiesof the GSE spectra and explained the reasons for the phenomenon in detail. In thelast, the theory result was obtained using the theory model in chapter4and fittedwell with the experimental data.4. the GSE properties of PbSe QD-doped liquid-core fiber under theinfluence of the temperature for the two QD size was studied. We focused on thechange of the peak position and peak intensity of the spectra when the temperatureincreased. Finally, the reasons of the experimental phenomena were analysized bytheory. This study has a certain application value in the fiber temperature sensor. |
PDF Full Text Request