The experimental part of this work describes a new method to determine the electrical characteristics of a single ZnO varistor grain-to-grain junction. The experimental results are described in statistical terms because each single barrier has been found to present its own electrical characteristics. There are ‘‘good’’ and ‘‘bad’’ barriers. On the basis of our experimental observations, we present an original approach to describing the current-voltage characteristics of ZnO varistors from the characteristics of individual junctions (series or parallel models). Finally, this work demonstrates that a ZnO sample having a low thickness and a large nonlinear coefficient value requires only ‘‘good’’ junctions.
A passively mode-locked Er3+-doped ZBLAN fiber laser around 3 μm with a wide wavelength tuning range is proposed and demonstrated. The laser cavity was comprised of a semiconductor saturable absorber mirror and a blazed grating to provide a wavelength tunable feedback. The central wavelength of the mode-locked fiber laser can be continuously tuned from 2710 to 2820 nm. The pulse train had a maximum average power of higher than 203 mW, a repetition rate of 28.9 MHz and a pulse duration of 6.4 ps, yielding a peak power of exceeding 1.1 kW. To the best of our knowledge, this is the first demonstration of a wavelength-tunable passively mode-locked mid-infrared fiber laser at 3 μm.
Adsorption behaviors of methane on four Sichuan Basin
shales at
different temperatures (318, 338, and 358 K) were experimentally investigated.
The adsorption equilibrium data were best fitted by using the modified
Hill-monolayer model, in which statistical physics theory was used.
Four physicochemical parameters of the number of CH4 molecules
per site (n), the density of receptors (N
m), total adsorbed quantity (Q
a), and energetic parameter (ΔE) were estimated.
The thermodynamic potential functions, including entropy (S
a), internal energy of adsorption (E
int), and Gibbs free energy (G
a), were derived. The results showed multianchorage manner occurs
during the adsorption process of CH4 on shale, and the
interactions between CH4 molecule and shales are Van der
waals forces or hydrophobic bond forces. The adsorption of CH4 on shale is spontaneous and globally exothermic. Besides,
the analysis of site energy distribution theory based on statistical
physical model showed methane molecules first occupied the high-energy
adsorption sites and then diffused and adsorbed on the low-energy
sites on shale, and the higher temperature resulted in the higher
heterogeneity.
A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.
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