Er~(3+) and Yb~(3+) doped phosphate glasses for eye-safe laser systems

摘要

Erbium doped optical glasses are effective media for active lasers generating eye safe radiation of a wavelength 1.53÷1.55μm. Development of erbium glass laser systems requires investigations aimed at improvement in glass properties and increases in effectiveness of laser radiation generation. Phosphate glass samples with various Cr_2O_3, Yb_2O_3, and Er_2O_3 contents based upon P_2O_5-Al_2O_3-BaO-PbO-K_2O 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~(3+) and sensitizers Cr~(3+), Yb~(3+) 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~(3+), Yb~(3+) and Cr~(3+)-doped glasses were measured in spectral range 190nm÷25μm at room temperature. The excitation and luminescence spectra were also recorded at room temperature on a spectrofluorometer using a diode laser as an excitation source. The presence of hydroxyl groups (OH~-) is important factor influencing glass structure. In glasses having high concentration of hydroxyl ions, strong attenuation of a lifetime of excited Er~(3+) ions was stated. In such a case the absorption band around 3.3μm 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.