We present results from our Ho:YLF regenerative amplifier (RA) producing up to 6.9 mJ at a repetition rate of 1 kHz and up to 12.9 mJ at a repetition rate of 10 Hz. At 1 kHz, we observe strongly bifurcating pulses, starting with certain round trip number, but the measurements identify a highly stable operation point that lies “hidden” beyond the instability region. This operation point allows the extraction of highly stable and high energetic output pulses. Suppression of bifurcation in our system is presented for repetition rates below 750 Hz and Ho:YLF crystal holder temperatures of 2.5 °C. We furthermore present a stability optimization routine for our Ho:YLF RA that was operated close to gain depletion at a repetition rate of 100 Hz. By varying the Ho:YLF crystal holder temperature the gain depletion level could be fine adjusted, resulting in a highly stable RA system with measured pulse fluctuations of only 0.35 %.
Zinc Oxide nanoparticles and nanorods have been synthesized at an optimum temperature of 60°C using aqueous
solution of zinc acetate and potassium hydroxide in methanol. Particle and rod like structures were obtained by merely
varying the relative concentration of the reagents. A variety of techniques like UV-Vis absorption spectroscopy, X-ray
diffraction (XRD), photoluminescence, Fourier transform infrared (FTIR) spectroscopy and scanning electron
microscopy (SEM) were used to carry out structural and spectroscopic characterizations. FTIR confirms the preparation
of zinc oxide. XRD shows the formation of well crystalline nature and wurtzite structure of prepared zinc oxide samples.
Grain sizes were also calculated using XRD data and found to be in 11-15nm range for all preparations. Presence of one-dimensional
structures in the rod samples were confirmed by SEM images. Blue shift of the absorption peaks were found
due to quantum confinement of excitons. Capping action of polyvinyl pyrrolidone (PVP) was also studied. Use of PVP
leads to the decrement in aspect ratio of rods but provides spherical shaped nanostructures. Enhancement of UV-emission
intensity with suppression of green emission intensity was observed by the use of PVP during preparation.