Amphiphilic Polymer-modified PbS Quantum Dot Optical Fiber Amplifiers

Fiber amplifier is one of the key components of the next generation optic fibercommunication system. With the increasing development of FTTH services, somehigher demands such as ultra-high-speed, large-capacity and ultra-long-range havebeen imposed upon fiber amplifiers. Because commercial rare earth doped opticalfiber amplifiers have limitation of narrow working bandwidth, quantum dot dopedoptical fiber amplifiers have emerged in recent years, due to their wide and tunablebandwidths.This paper presents a PbS quantum dot (QD) optical fiber amplifier withenhanced thermal stability, which combines the high quantum yield and thermalstability of oleic acid capped PbS QDs (OLA-QD). It is proved that carboxyl group ofOLA-QDs is more stable than amido group of OLAm-QDs, where oleic acid ligandsare tightly attached to the quantum dot surface. All the above features have greatadvantages to improve the thermal stability of optical fiber amplifier.We can conclude of this thesis: firstly, synthesis and characterization of PbS QDsand their optical properties are presented. Then OLAm-QDs are ligand exchangedwith oleic acid. Under the same conditions, fluorescence intensity of the QDs beforeand after ligand exchange is compared. Enhanced fluorescence intensity had beenfound from the OLA-QDs.Secondly, the temperature characteristics of the two kinds of QDs in the sameenvironment were tested. The fluorescence intensity of OLAm-QDs decreased withincreasing temperature, while a temperature antiquenching fluorescence of OLA-QDswas observed, which further verified the enhanced stability of OLA-QDs.Thirdly, the characteristics of optical fiber amplifiers based on OLAm-QDs andOLA-QDs were compared by studying the amplification performance and thermalstability of two QDs optical fiber amplifiers under the same conditions. The opticalfiber amplifier based on OLAm-QDs showed a continuous reduction in amplification on heating, while the optical fiber amplifier based on OLA-QDs exhibited fairlystable and reversible amplification signals during a heating-cooling cycle.Finally, a connection between quantum dot optical fiber amplifier and pumppower was studied, we found that the gain of QD optical fiber amplifier increased tosaturate with pump power. At the end of this article, a conclusion on the researchwork is given, and some suggestions to improve the performance of QDs basedoptical fiber amplifiers are proposed.