Er3+- and Yb3+- doped phosphate glasses for eye-safe laser systems

Abstract

Erbium doped optical glasses are effective media for active lasers generating eye safe radiation of a wavelength 1.53 divided by 1.55 micrometers . Development of erbium glass laser systems requires investigations aimed at improvement in glass properties and increase in effectiveness of laser radiation generation. Phosphate glass samples with various Cr<SUB>2</SUB>O<SUB>3</SUB>, Yb<SUB>2</SUB>O<SUB>3</SUB> and Er<SUB>2</SUB>O<SUB>3</SUB> contents based upon P<SUB>2</SUB>O<SUB>5</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB>-BaO-PbO- K<SUB>2</SUB>O oxide system were prepared. The obtained phosphate glasses are characterized by advantageously low thermal expansion coefficient what is important for increase of glass resistance to thermal shock, especially when they are applied as rods for lamp pumped lasers. The effect of changing concentrations of Er<SUP>3+</SUP> and sensitizes Cr<SUP>3+</SUP>, Yb<SUP>3+</SUP> as well as glass base compositions on luminescence properties were investigated. The spectral and spectroscopic properties were measured for these glasses. Absorption spectra of these Er<SUP>3+</SUP>, Yb<SUP>3+</SUP> and Cr<SUP>3+</SUP>-doped glasses were measured in spectral range 190 nm divided by 25 micrometers at room temperature. The excitation and luminescence spectra were also recorded at room temperature on a spectro fluorometer using a diode laser as an excitation source. The presence of hydroxyl groups is an important factor influencing glass structure. In glasses having high concentration of hydroxyl ions, strong attenuation of a lifetime of excited Er<SUP>3+</SUP> ions was stated. In such a case the absorption band around 3.3 micrometers was observed. Concentration of OH groups was reduced due to adequate special melting process of glass. Carried out investigations on thermal, optical, and spectroscopic properties of the obtained glasses showed their good quality, ensuring possibility of their application in laser systems.