Optical And Spectral Properties Of Praseodymium Ions Doped Germanium Tellurite Glasses

Extensive interests have been paid to the investigation on spectral properties of rare earth(RE) ions and the preparation of RE doped luminescence glasses, attributing to theirfasinating applications in solid state lighting, full-color displays, laser communication, opticaldata storages, and biomedical instruments. Among various RE ions, praseodymium ions (Pr3+)have been researched extensively, since Pr3+hold multi-emissions in both visible (VIS) andnear-infrared (NIR) wavelength regions, possess colorful luminescence, and can be excited bycommon UV and VIS lighting source. However, due to the small energy gap of Pr3+, efficientradiation transition was unlikely to be achieved in high phonon energy host materials. Mostresearches of Pr3+were concentrated on non-oxide glasses. Middle-low phonon energyheavy-metal germanium tellurite (HGT) glass, which hold favourable chemical and thermalstability and was promising to be draw into optical fiber, have been prepared in this work.Colorful VIS luminescence and ultra-broadband NIR emission covering from1300nm to1700nm of Pr3+in HGT glass have been achieved. The optical spectral behaviors of Pr3+inHGT glass have been systematacially studied, which demonstrating that Pr3+doped HGTglass hold great applications in ultra-broadband optical communication and photodynamiccancer treatment. The followings are results this work achieved:1. In this work, Pr3+doped HGT glasses with different concentrations have beendesigned and fabricated using high tempreture fusion method. The difference value betweentransformation temperature and crystallization temperature of Pr3+doped HGT glassesexceeded100°C, indicating a favorable crystallization stability and wide fiber drawingoperation temperature range.2. The emission spectral of Pr3+doped HGT glass, due to3P03H5,3P03H6,3P03F2,3P03F3and3P03F4radiation transition, has been recorded. The excitation spectral coveredthe420nm500nm wavelength region, which indicated that Pr3+doped HGT glass can beeffectively obtained by muitiple excitation and produced a series of dynamical colorfluorescence. The average lifetime of645nm and613nm emissions were calculated to be12.35s and14.59s, and the maximal emission cross-section of3P0â†'3F2,3P0â†'3H6and1D2â†'3H4transitions were drived to be127.16×1021cm2,15.09×1021cm2and4.95× 1021cm2。3. Adoping the integrating sphere fluorescent test system, the absolute spectralparamenters, such as power distribution, photon number distribution, and radiation flux, wereobtained. The highest flurescence intensity is3.29W/nm, the total radiant flux in the570720nm orangish-red region was219μW, and the quantum yield of Pr3+are solved to be11.80%, respectively. Pr3+doped HGT glass holds great promising for photodynamic therapy(PDT) treatment and clinical trials.4. The ultra-broadband1.5m near-infrared emission from1D21G4energy transitionof Pr3+doped HGT glass was recorded, the emission covered1300nm1700nm wavelengthregion and possess the full width at half maximum (FWHM) of140nm. The excitationspectral covered from420nm to460nm. The lifetime of1.5m emission was deprived to be68.98s, and the maximal emission cross-section was derived to be7.46×1021cm2. Thus, itis safe to say that, effective ultra-broadband signal amplification at O-, S-, C-, L-and U-bandis reasonable to be expected in Pr3+doped HGT glass.5. Judd-Ofelt (J-O) analysis was carried out based on the absorption spectrum. The J-Ointensity parameters t(t=2,4,6) are derived to be3.141020cm2,10.671020cm2and3.951020cm2, respectively. Besides, the spontaneous emission probability, fluorescencebranching ratios, and lifetime were also been calculated.