The Establishment Of The Integrating Sphere Fluorescent Test System And Its Application In Measuring Absolute Spectral Parameters Of Rare-earth Doped Optical Glasses

RE ions doped luminescence and laser materials have attracted considerable attention,due to potential applications in areas such as color display, optical storage, optical detectors,bulk lasers, waveguide lasers and optical amplification. Therefore, it is essential to reveal theoptical properties. An integrating sphere coupled with a CCD detector has been applied toabsolute measurements, and the method was applied to characterize optical parameters andquantum yield of materials. A standard halogen lamp was used to calibrate measurementsystem and it was considered as an accurate way to characterize luminescence parameters forluminescence and laser material. Of the oxide glasses, tellurite glasses represent acompromise between the demand for proper mechanical strength and good chemicaldurability and the desire for a low-phonon-energy host, which hold great promise for thecommercial use of special-band signal amplifiers traditionally taken up by non-oxide glasses.Meanwhile, germanium-containing glasses show sufficient photosensitivity that cancontribute to the precise control of refractive index change, demonstrating the attractiveapplication prospect in gain-flatten amplifier by long-period grating UV-writing. Withaddition of lead oxide, the density and refractive index increase almost linearly, therefore largerstimulated emission cross-section, lower non-radiative decay rate and higher radiative quantumefficiency in visible and NIR wavebands are expected. Based on this consideration, theintegrating sphere fluorescent test system was established and Dy3+doped heavy metalgermanium tellurite glasses were designed, and the optical and spectral properties of Dy3+were studied, and the integrating sphere-method was applied to measure absolute spectralparameters of the glasses. The followings are results this work achieved:1. The integrating sphere fluorescent test system was successfully established. Thismeasurement route was considered as a repeatable and reliable way and the test procedurewas mastered. An integrating sphere coupled with a CCD detector has been applied to absolutemeasurements, and the method maked it possible to obtian fluorescence absolute spectralpower distribution of weak luminescence samples. A standard halogen lamp was used tocalibrate measurement system and it was considered as an accurate way to characterize luminescence parameters for luminescence and laser material.2. Thermodynamic properties of the heavy metal germanium tellurite (NZPGT) core andcladding glasses have been investigated. The refractive index of rare earth doped fiber core isgreater than that of the cladding, which is in the required range of the relative refractive index.The temperature difference values (ΔT) of crystallization temperatures and transitiontemperatures in Dy3+doped heavy metal germanium tellurite core and cladding glasses arecalculated to be97and101°C, respectively, indicating that the heavy metal germaniumtellurite glasses exhibit good stability against crystallization, and it can be considered a goodcandidate for fiber drawing.3. Based on optical absorption, Judd-Ofelt parameters Ω2, Ω4and Ω6have been derivedto be7.34×1020,2.75×1020and1.45×1020cm2, respectively. Then the radiative transitionprobabilities, radiative lifetimes and fluorescence branch ratios of Dy3+in NZPGT glasseswere calculated. The maximum stimulated emission cross-sections σem-maxwere derived to be0.33×1021,3.66×1021, and0.67×1021cm2for conventional visible emissions assigned to4F9/2â†'6HJ(J=15/2,13/2,11/2) transitions, respectively. Infrequent multi-peak NIR emissionswere recorded in the spectral range of9001500nm, among which the values of σem-maxweresolved to be1.05×1022and1.56×1022cm2for～1.02and～1.18μm emission bands.Internal quantum efficiency for the4F9/2level of Dy3+was determined to be88.44%. Effectivemultichannel radiative emissions reveal a potential in developing fiber-lighting sources,tunable lasers, and NIR optical amplifiers.4. Fluorescence spectra of Dy3+-doped germanium tellurite (NZPGT) glasses have beendeterminedusing an integrating sphere, which connected to a CCD detector. Under thepumping of a violet light emitting diode (LED), the total radiant flux and total luminous fluxhave been calculated to be1172μW and34mlm, respectively. The radiant flux for the fourvisible emission bands of Dy3+was derived to be86μW, which occupied7.34%of the whole.The total quantum yield for the visible fluorescence of Dy3+has been calculated to be12.38%.Under the pumping of a blue LED, the total radiant flux and total luminous flux have beencalculated to be875μW and426mlm, respectively. The radiant flux for the three visibleemission bands of Dy3+was derived to be181μW, which occupied2.17%of the whole. Thetotal quantum yield for the visible fluorescence of Dy3+has been calculated to be7.10%. Theabsolute spectral parameters provide a valuable reference for further development of rare-earth ions doped solid-state luminescent materials.