Spectroscopy properties of aluminosilicate and fluoreide glasses doped with Nd3+ and Pr3+ and Pr3+/Yb3+

Author(s)

Édison Pecoraro

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 1999-04-26

Examining board members

Luiz Antonio de Oliveira Nunes; Hermi Felinto de Brito; Marian Rosaly Davolos; Máximo Siu Li; Maria Cristina Terrile

• Advisor: Luiz Antonio de Oliveira Nunes

Abstract

This work presents the spectroscopic study results of the glass matrices CASM (47,4% CaO, 41,5% Al2O3, 7,0% SiO2 and 4,1% MgO doped with Nd3+) and PbF (30PbF2-20GaF3-15InF3-15ZnF2-20CaF2 doped with Pr3+ and Pr3+/Yb3+). The objective was to evaluated theses matrices as four level lasers active media, with laser emissions in 1076nm (4F3/2 &#8594 4I11/2 of the Nd3+), 1300nm (1G4 &#8594 3H5 of the Pr3+) visible and near UV spectral regions. The results are discussed based on spectra of transmittance, absorption, infrared, visible and upconversion. Besides the lifetime of 4F3/2 (Nd3+) and 1G4 (Pr3+</sup), the Raman spectra, the phenomenological parameters calculation of Judd-Ofelt theory to Nd3+ and Pr3+ and energy transfer between Pr3+ &#8594 Yb3+ are discussed too. Both, the CASM matrix and the samples doped with Nd3+, show infrared edge at 4,5&#956m. The absorption spectra show broad and strong bands at 800 and 590nm, ideal for pumping it with diode and dye lasers, respectively. The emission in 1076nm show luminescence quenching from 1.0% of Nd2O3, for the pumping at 514nm (300 and 77K), and from 2,5% for the pumping at 800nm (300 and 77K). Due to the cross-relaxation process and multi phonos decay. The emissions in the visible spectral region are observed only by upconversion way. Calculated quantum efficiency of 0.5% Nd2O3 sample for 1076nm emission by Judd-Ofelt model was 95%. The radiative lifetime of 4F3/2 (1076nm) is 320#956s and the experimental one is 300&#956s, for the same sample. From these spectroscopic results and other properties such as microhardness (800MPa), glass transition temperature (750&#176C), waterless samples preparation and chemical stability, the CASM glasses can be considered as an appropriate to laser active medium or windows to optical applications. Laser action at 1076nm was observed with pumping in 514 and 800nm with a Ti:Saphire laser. The efficiency is higher when the pumping is 800nm. Both, the PbF matrix and the Pr3+ and Pr3+ /Yb3+ doped samples, show infrared adge at 8,8&#956m. The emission at 1300nm (Pr3+) is weak due to the low absorption coefficient at 980nm. Was not observed emission at 1300nm with the pumping at 514 and 800nm. The Yb3+ inclusion in the 1% Pr3+ sample increase 40 times the integrated área under the emission banda t 1300 nm compared with the samples without Yb3+. Calculations of energy transfer probabiblity show that the process Yb3+ &#8594 Pr3+ is 8 times more probable than Pr3+ &#8594 Yb3+. The Judd-Ofelt calculations to Pr3+ result in negatives values to &#9372. Only when the Florez and Malta approximations are taken into account the values are positives and the calculated oscillator strength error is minimized. From the emission at 1300nm and chemical stability, the PbF glasses doped with Pr3+/ Yb3+ are candidates to be employed in optical amplifiers. (AU)