Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Photonics technology,laser technology > Optical waveguide and integrated optics > Fiber optic components

CdSe/ZnS Quantum Dot Doped Fibers and the Gain Performance

Author LinYanGuo
Tutor ChengCheng
School Zhejiang University of Technology
Course Optics
Keywords CdSe/ZnS quantum dot quantum dot doped fiber re-absorption/excitation effect photoluminescence spectra red shift
Type Master's thesis
Year 2011
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In recent years, semiconductor nanocrystals (quantum dots) and the applications have been investigated widely. This dissertation focuses on the three hands as follows.(1) We develop several experimental methods to fabricate the QD doped fibers in the laboratory, including direct tip-drawing progress and an injection method. CdSe/ZnS quantum dot doped fibers (QDFs) are prepared in this study. By measuring the photoluminescence (PL) spectra of the QDFs with various doped concentrations and fiber lengths, we observe the red shift of the PL-peak wavelength of the QDFs, which is dependent on the doped concentration and the fiber length. The red shift as a function of fiber length in four fiber-core background materials (toluene, ultraviolet curable adhesive, hexane, and decane) is determined. Although the increased/decreased rate of the red shift depends on the core material and the doped concentration, the maximum red shift even with the FWHM of the first absorption peak of the QD.(2) The CdSe/ZnS quantum dot doped fibers (QDFs) are fabricated choosing an ultraviolet (UV) curable adhesive as fiber-core background materials. The PL spectra are measured in different fiber lengths and with different doping concentrations. The absorption coefficient of the QD in such a background is also determined. There is evidence to show that the PL-peak intensity depends on both the doping concentration and the fiber length. The UV curable adhesive can be a desirable choice for preparing the QDF in laboratories due to small absorption, low shrinkage factor, matching fiber-cladding refractive index, and steady optical property.(3) A CdSe/ZnS quantum dot doped fiber amplifier is initially builtup in the laboratory. The signal gain is measured with different doping concentrations and fiber lengths by adopting a longitudinal pumping formation. At the fiber length of 7cm and with the doping concentration of 0.038mg/mL, a gain of 3.8dB is obtained for 658nm signal under the pumping laser of 100mW and 473nm.As a initial research of the quantum dot doped fiber amplifier, the study presented in this dissertation provides useful experimental methods of the QD doped fiber and a theoretical analysis for the QD. The obtained results can be advantageous to realization of the QD doped fiber amplifier with desirable performance on the bandwidth, gain and noise in the future.

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