Generation of 103 fs mode-locked pulses by a gain linewidth-variable Nd,Y:CaF2 disordered crystal

We have demonstrated a diode-pumped passively mode-locked femtosecond Nd,Y:CaF2 disordered crystal laser for the first time to our knowledge. By choosing appropriate Y-doping concentration, a broad fluorescence linewidth of 31 nm has been obtained from the gain linewidth-variable Nd,Y:CaF2 crystal. With the Nd,Y:CaF2 disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration as short as 103 fs, average output power of 89 mW, and repetition rate of 100 MHz. To our best knowledge, this is the shortest pulse generated from Nd-doped crystal lasers so far. The research results show that the Nd,Y:CaF2 disordered crystal will be a potential alternative as gain medium of repetitive chirped pulse amplification for high-peak-power lasers.

[Synthesis and bacteriostatic activity of 2-furanthiocarboxyhydrazones and their transition metal complexes]

In this paper, 9 compounds of 2-furanthiocarboxyhydrazones and 13 of their transition metal complexes have been synthesized and tested for bacteriostatic activity against several kinds of bacteria. The results showed that all the compounds tested possessed antibacterial activity. The complexes of Cu(II), Ni(II) and Zn(II) ions display higher activity against gram-positive bacteria than 2-furanthiocarboxyhydrazones and the other complexes. The complex of Ag(I) ion is more active against gram-negative bacteria, as compared to 2-furanthiocarboxyhydrazones and the other complexes. The results are also in accord with the earlier idea that the "NCS" group is the active site and that their activity has certain relation with their complexing ability.