SOL-GEL SYNTHESIS OF UNDOPED AND Er~(3+) - DOPED GeO_2 GLASSES AND THEIR SPECTROSCOPIC PROPERTIES INCLUDINGUPCONVERSION FLUORESCENCE

摘要

Transparent glassy dried and heated gels of undoped and Er~(3+)-doped GeO_2 were prepared by the sol-gel method and characterized by fundamental properties including DTA, density, specific surface area, IR and XRD. These gels showed interesting spectroscopic properties regardless of Er~(3+) : a weak ESR signal of g=2.003, a broad fluorescence which has peaks at 460 and 500 nm under excitation of 310 nm, and a prolonged green afterglow (only in the heated gel). Under excitation with an 805-nm diode laser, the Er~(3+)-doped heated gel exhibited upconversion fluorescence in the green and red regions. A broad ESR signal of g≒6 due to Er~(3+) was observed in the doped dried gel, which was turned into a peak-less signal accompanying zero field absorption in the heated gel.