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This paper describes the investigation of autoionizing states near the first ionization limit of rare-earth element Dy. The 62, 51, 97 and 25 new autoionizing states resulting from the states of 4f10(5I8)6s6p(3P20) 3I70, 4f9(6H0)5d2(3F) (8G0)6s9G70, 4f9(6F0)5d6s2 7H70 and 4f95d6s2 7K70, respectively, were found by using a laser resonance ionization time-of-flight mass spectrometer (LRI-TOFMS). The photoionization efficiencies for different channels were compared with each other. In addition, the Shore-Fano parameters of autoionizing states were determined by a nonlinear fitting program.

This paper describes the investigation of high-excited states of Dy, which includes the measurement of high Rydberg states and autoionizing states, by means of laser resonance ionization spectroscopy (LRIS). Two high Rydberg series (n> 40), 4f10(5I8) 6sns and 4f10(5I8) 6snd, have been obtained by exciting the state of 4f10(5I8) 6s6p (3P20)5I80 using two-step laser excitation-electric field ionization method. With the data obtained, we determined the first ionization potential of Dy. It is 47901.7 ± 0.6 cm-1, that is, about one order more accurate than the results given in the literature. Using the same technique, we found 97 autoionizing states by exciting the state of 4f95d6s (7H70).

We observe the phenomenon of priority oscillation of the unexpected σ-polarization in high-power Nd:YVO4 ring laser. The severe thermal lens of the σ-polarized lasing, compared with the π-polarized lasing, is the only reason for the phenomenon. By designing a wedge Nd:YVO4 crystal as the gain medium, the unexpected σ-polarization is completely suppressed in the entire range of pump powers, and the polarization stability of the expected π-polarized output is enhanced. With the output power increasing from threshold to the maximum power, no σ-polarization lasing is observed. As a result, 25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated.