Fluorescence of Samarium Ions in Strontium Bismuth Borate Glasses Lucas Elliott Mark S. Boley, P. K. Babu, Saisudha B. Mallur

Overview Introduction Experimentation Results Summary The importance and uses of rare earth doped glasses Explanation of fluorescence Experimentation Samples Laser excitation and fluorescence measurements Origin analysis Results Summary

Rare Earth Doped Glasses Promising in many industrial and research applications Including: Windows Camera lenses Lasers Waveguides Optical Fibers Research focuses on glasses doped with Sm3+

Host Glass Borate glasses are used as the host material for the samarium ions This experiment uses strontium bismuth borate glass These were bismuth borate glasses A portion of borate is replaced with equal parts strontium This replacement occurred in 5 mol percentage increments

Fluorescence Luminescence is a general term to describe the emission which can be excited in various ways. Photoluminescence relates to excitation by photons. Fluorescence is a type of photoluminescence characterized by an exponential afterglow when excitation is removed. The emitted photon energy is generally lower than that of excitation.

Fluorescence of Sm3+ Ions Emits a strong reddish orange light This fluorescence is due to transitions from the 4G5/2 state Two of these transitions are especially important: 4G5/26H7/2 is an electric dipole (ED) transition 4G5/26H9/2 is a magnetic dipole (MD) transition

Term Symbols Expressions used in the previous slides, such as 4G5/2, are known as term symbols. These symbols are of the of the form 2S+1LJ. L indicates the total orbital angular momentum. Letters S,P,D,F,G, and H corresponds to 0,1,2,3,4, and 5. The superscript term refers the terms multiplicity, where S is the total spin quantum number. The subscript term is given by J = L+S, L+S-1,…,L-S.

Dipole Transitions The transition corresponding to the electric dipole (ED) is very sensitive to environmental changes of the Sm3+ ions. However, the magnetic dipole (MD) transition is not sensitive to these changes surrounding the ions. The ratio of the area under these spectral peaks shows the distortion of symmetry of these rare earth ions. Therefore, it points to structural changes within the glass matrix.

Samples The experiment uses four samples. Formula: xSrO : (69-x) B2O3: 30 Bi2O3: 1.0 Sm2O3 Each of samples was prepared using the melt quench technique. Sample 1 X=0 Sample 2 X=5 Sample 3 X=10 Sample 4 X=15

Excitation Three excitation wavelengths: 405.0 nm 457.9 nm 488.0 nm 457.9 and 488.0 nm laser lines were obtained using an Ar ion laser 405.0 was obtained with a diode laser.

Ar ion laser Located in CH 524 More powerful of the two lasers used in this experiment Data collected using LabVIEW software

Diode Laser Located in CH 109 Less powerful Similar configuration as the Ar ion laser with fewer filters

Experimental Methods Emission spectra was measured for each sample using each excitation wavelength. Spectra was collected across a range of 500 to 750 nm. The corresponding spectrometer and PC recorded the data in an Excel file. This data was then transferred to the program Origin. The emission spectra was decomposed by fitting with Gaussian curves.

Experimental Methods The emissions are the result of Stark split transitions. Therefore, the area of the Gaussian curves were added to obtain the area under each transition peak. Finally, these areas were used to obtain the ED/MD ratio. This ratio shows the symmetry of the rare earth ions in the glass matrix.

405.0 nm Sample 1 Sample 2 Sample 3 Sample 4

405.0 nm

457.9 nm Sample 1 Sample 2 Sample 3 Sample 4

457.9 nm

488.0 nm Sample 1 Sample 2 Sample 3 Sample 4

488.0 nm

ED/MD Sample 405.0 nm 457.9 nm 488.0 nm 1 2.227 ± 0.035 1.714 ± 0.036 1.795 ± 0.067 2 2.208 ± 0.033 1.617 ± 0.036 1.736 ± 0.069 3 2.172 ±0.089 1.628 ± 0.030 1.316 ± 0.059 4 2.163 ± 0.089 1.824 ± 0.034 2.150 ± 0.023

Results For the 488.0 nm excitation, the ED/MD ratio decreases before increasing drastically. This excitation wavelength has the largest variance of the ED/MD ratio as concentration changes.

Results For the 457.9 nm excitation the ED/MD ratio decreases initially, then increases with increased concentration.

Results For the 405.0 nm excitation, the ED/MD ratio remains constant as the concentration of SrO increases. The highest ED/MD ratio is for 405.0 nm excitation This implies that this excitation wavelength is an efficient wavelength for increased fluorescence intensity.

Summary The importance and uses of rare earth doped glasses Explanation of fluorescence Samples Laser excitation and fluorescence measurements Origin analysis Results