Downconversion luminescence studies in Er3+activated P2O5+Gd2O3+NaF+AlF3 glasses for 1.54 pm NIR laser applications

A series of PGNAEr:(60-x)P2O5 + 7Gd2O3 + 25NaF + 8AlF3 + xEr2O3 (here, x = 0.1, 0.5, 1.0, 2.0 and 4.0 mol%) glasses have been successfully fabricated using the melt quenching technique. X-ray diffractometer has been used to study the amorphous-like structure of the PGNAEr glasses. Spectral measurements of optical absorption and excitation of PGNAEr glasses are studied in both visible and near-infrared wavelength range. The density (2.87-3.16 (g/cm3)) and refractive index (1.535-1.544) are found to increase with Er2O3 concentration, and the absorption spectrum of PGNAEr20 glass plays a vital role in evaluating omega lambda (lambda = 2, 4, 6) and laser parameters. The down conversion emission process of PGNAEr glasses is examined in the near-infrared (1400-1700 nm) range upon the radiations at 522 nm (visible) and 980 nm (near-infrared) wavelengths. The emission at 1.54 pm (1545 nm) is observed to be enhanced by a factor of 7 when excited at 522 nm compared to the 980 nm laser source. The observed near-infrared emission from the PGNAEr glass system covers the C + L (1530-1600 nm) bands and third telecommunication window (1440-1530 nm). Using the McCumber's theory, the emission cross-section is calculated to be around 4.20 x 10-20 cm2 from the absorption cross-section of 2.70 x 10-20 cm2 for the PGNAEr glass system. The calculated gain bandwidth (636 x 10- 28 cm3) and gain cross-section (6.93 x 10-21 cm2) indicate that PGNAEr glasses are a promising candidate for optical gain media in the 1.54 pm wavelength region.