Energy transfer and upconversion in Yb:YAG and Yb:Er:YAG

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7197265

Lacovara, P

Energy transfer and upconversion have been studied in ytterbium, and ytterbium-erbium doped YAG (yttrium-aluminum garnet Y[sub 2]Al[sub 5]O[sub 12]). The energy-transfer probabilities were calculated for Yb-Yb, Yb-Er, and Er-Yb interactions, as well as for Er-Er and Yb-Er upconversion. The transfer of excitation from ytterbium to erbium was found experimentally to be efficient at Er concentrations above about 1%, with an Yb concentration of 6.5%. The Burshtein hopping model for donor migration-assisted transfer was applied to the Yb-Er system for different Er concentrations. Fitting the decay predicted by the Burshtein model to the Yb fluorescence gave a value for the Yb-Er dipole-dipole interaction strength which was in very close agreement with the calculated value, but discrepancies were noted for the donor-donor interaction. Upconversion was observed during pulsed measurements, and studies in detail with intense CW pumping. The Yb-Er upconversion was observed to dominate the Er-Er upconversion in the Yb-Er samples. Values for the Yb-Er and Er-Er ([sup 4]I[sub 1 1/2]) upconversion coefficients were determined from quantitative measurements of the [sup 4]S[sub 3/2] fluorescence which these processes generate, and measurements of the change in [sup 4]I[sub 1 1/2] population with increasing pump density. The quenching of nominally pure Yb:YAG by trace rare-earth impurities was also studied. The time dependence of the Yb fluorescence decay in some high-concentration samples suggested a fast quenching process active at high excited-ion densities, and a slower one at lower excited-ion densities. Study of the cooperative luminescence emitted by excited Yb pairs suggested a quenching mechanism acting preferentially on pairs. Sensitive Ar[sup +]-ion laser-pumped fluorescence measurements showed the presence of high ppm levels of several impurities, including Er, Tm and Cr. Pumping the ytterbium at 940 nm using pulsed and CW lasers revealed Er and Tm upconversion.

• Research Organization: Boston Coll., Chestnut Hill, MA (United States)
• OSTI ID: 7197265
• Country of Publication: United States
• Language: English

Related Subjects

664100* -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHROMIUM
DOPED MATERIALS
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
ERBIUM
EXCITED STATES
FERRITE GARNETS
MATERIALS
METALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RARE EARTHS
SILICATE MINERALS
THULIUM
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YTTERBIUM
YTTRIUM COMPOUNDS