Search

We report the results of a direct search for the 229Th (Iπ = 3/2+← 5/2+) nuclear isomeric transition, performed by exposing 229Th-doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s ≲ τ ≲ (2000-5600) s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches. [ABSTRACT FROM AUTHOR]

Laser operation at 2.8 microm in BaY(2)F(8) with erbium concentrations of 7.5% and 20% is investigated under laser-diode pumping at 967 nm. Output powers as high as 250 mW and slope efficiencies as high as 24% are obtained. Results are comparable with those of Er(3+):LiYF(4) under the same pump conditions. Slope efficiencies above 30% are predicted for optimized erbium concentrations.

Relatively fast self-pumped phase-conjugate and four-wave-mixing rise times are reported in n-type cobalt-doped barium titanate. With the crystal oriented in a 45 degrees cut as compared with the same crystal in a 0 degrees cut we find a factor of 3 decrease in the 0-90% rise time to 800 ms with 25-mW input power at 514.5 nm. Also, the self-pumped phase-conjugate reflectivity increases from 20% to 40%. We deduce that the phase conjugation is from internally seeded stimulated photorefractive backscattering. The four-wave-mixing rise time of the 45 degrees -cut crystal is 4 ms with a reflectivity of 48% when the pumping beams are derived from self-pumped phase conjugation that has an input power of 25 mW.