High-spin states in 190 Tl have been studied experimentally by using the 160 Gd( 35 Cl,5n) fusion-evaporation reaction at beam energies of 167 and 175 MeV. A rotational band built on the πh 9/2 ⊗ νi 13/2 configuration with oblate deformation has been established for 190 Tl. Spin values are assigned by adopting the results from α-γ decay work for 194 Bi found in the literature. With the configuration and spin-parity assignments, the low-spin signature inversion has been revealed for the πh 9/2 ⊗ νi 13/2 oblate band in 190 Tl. It is the first experimental observation of low-spin signature inversion for a band associated with the oblate πh 9/2 ⊗ νi 13/2 configuration. The low-spin signature inversion for the oblate πh 9/2 ⊗ νi 13/2 band can be interpreted by the two-quasiparticle-plus-rotor model including a J-dependent p-n residual interaction.

A 10 kW peak power, 10 ns duration, and 6 kHz repetition rate fiber laser system at 1553 nm based on an Er/Yb co-doped large-mode-area fiber, is demonstrated experimentally. The seed laser is provided by a DFB laser switched with a semiconductor optical amplifier. Its optical spectrum, linewidth, and beam quality are measured and discussed. This pulsed laser with short pulse duration and high peak power could be a candidate for the laser source of time-of-flight light detection and ranging (LIDAR).

The cross-section is crucial for quantitative characterization and analysis of the absorption process. A model on the absorption cross-section of the simultaneous two-photon excitation in Rb-vapor four-wave mixing process is established by using the coupled-wave equation. Taken into account of the hyperfine structures for Rb andRb, the third-order susceptibility and hyperfine line strength are calculated respectively. Then, the influences of hyperfine transition on cross section are investigated and simulation results agree well with the experiment results. The calculated results suggest that high pumping power intensity is essential in Rb two-photon excitation, while narrow linewidth is the limiting factor of high absorption efficiency by comparing normalized absorption profile between pumping beam and two-photon excitation process. Additionally, two approaches to improving absorption efficiency, linewidth narrowness of the pumping beam and absorption linewidth broadening, are proposed.

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