Experimental Study Of Photonic Crystal Fiber Doped With PbS Quantum Dots

Photonic crystal fibers(PCFs)have attracted great attention due to its unique optical properties and features that ordinary fibers do not possess(such as single-mode transmission without cut-off wavelength and good dispersion characteristics).Semiconductor nanocrystal quantum dots(QDs)have also been widely studied due to their high quantum yield and tunable absorption-radiation peak wavelength.Using the special optical properties of PCFs,we could fabricate QDs-doped PCFs by filling QDs into hollow hole of PCFs.Then we study the optical transmission characteristics to develop new or unique optical fiber devices.This is a subject that has not been carried out before and is of great significance for fiber optical fiber transmission.In this dissertation,we first experimentally fabricate a PbS quantum-dots-doped photonic crystal fiber(QD-PCF)working in near infrared 1400~1650 nm.The fluorescence transmission loss,photoluminescence(PL)spectrum and bandgap of QD-PCF in near infrared range of 1400~1650 nm are studied experimentally.We measure the absorption of QD-PCF for 980-nm pump and 1550-nm signal light.Upon the excitation of 980-nm pump,the photoluminescence(PL)spectra of QD-PCF are measured.and the doping concentration and the fiber length are determined,which has the strongest PL intensity at the central wavelength of 1550 nm.There is evidence to show that the PL intensity of QD-PCF is much higher than that of the QD doped single-core fiber(QDF),appearing multiple intensity peaks spacing a short distance related with the doping concentration.A comparison between the QD-PCF and un-doped PCF shows that the bandgap hasn't been changed by the QD doping.The threshold and saturated pumping power of QD-PCF are also measured.The threshold power is close to that of QDF.In this dissertation,we fabricate a kind of QD-PCF that QDs are uniformly attached on the inner wall of PCFs holes,while we retain the original photonic bandgap structure of PCFs.This brings benefits and convenience to the experiment and work.According to the need of experiment,we could control the density of QDs attaching onthe inner wall of PCFs holes by adjusting the concentration of QDs-doped solution.So that we can select the optimum doping concentration conveniently.In addition,PL generated by QDs propagates in the bandgap of PCFs with less transmission loss and higher gain.It has positive significance for further studies on near infrared optical fiber devices based on PCFs.