Well-aligned and randomly grown multiwall nanotubes (MWNTs) fabricated by the radio-field-induced self-bias hot-filament chemical vapour deposition method demonstrate that the growth mechanisms are either 'tip growth' or 'base growth' depending on the size of the catalyst metal particles involved. The carbon nanotubes (CNTs) can also be successfully grown on iron-like bulk alloys when preceded by hydrogen plasma etching. The high yield of CNT fabricated on oxidized metal alloys is attributed to the high active surface area that ensues from etching. The change in field emission currents of MWNTs with temperature is not sensitive but is detectable within the range 300-20 K. This is interpreted to be due to the high aspect ratio of CNTs.
We report a single-longitudinal-mode CW diode-pumped Nd:YVO(4) laser emitting at both 1064 and 1342 nm with 10% optical efficiency at 20-W pump power. The measured spectral widths at 1064 and 1342 nm were less than 450 MHz and 400 MHz, respectively. The two emission wavelengths can be independently tuned over the lasing bandwidths of the dual-wavelength laser.
We report a low-threshold, narrow-line THz-wave parametric oscillator with an intra-cavity grazing-incidence grating and a 1-mm thick, 45-mm long lithium-niobate planar waveguide. When pumped by an actively Q-switched Nd:YAG laser, the threshold energy and intensity of the parametric oscillator were about 2.2 mJ and 70 MW/cm(2), respectively. The linewidths of the output THz wave were 12 and 134 GHz with and without the intra-cavity grating, respectively.
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