Optical photoluminescence spectroscopic method for detection of impurities, hazardous materials, pesticides, and
pollutants in water resources, both qualitatively and quantitatively, is presented. The method is based on synchronous
fluorescence spectroscopy (SFS) of organic aromatic compounds, or poly-aromatic hydrocarbons (PAH), and is carried
out by following simultaneously their excitation and emission spectra. The full excitation emission matrix (EEM)
generated in this way provides a 2-D and 3-D fluorescence map of the tested sample and the diagonals through the axes
origin provide the synchronous fluorescence spectra at a constant wavelengths differences between the emission and
excitation wavelengths, thus enabling multitude components identification. This map contains all the relevant
spectroscopic information of the tested sample, and serves as a unique "fingerprint" with a very specific and accurate
identification. When compared with pre-determined spectra and calibration curves from a "databank", there is a one-toone
correspondence between the image and the specific compound, and it can be identified accurately both
qualitatively and quantitatively. This method offers several significant advantages, and it provides a sensitive (ppm
detection level), accurate and simple spectroscopic tool to monitor impurities and pollutants in water. The design and
performance of the spectrofluorimeter prototype, as well as the software development and analysis of chemical organic
compounds and mixtures in water will be discussed in this paper.
KEYWORDS: Weapons, Fiber lasers, Chemical lasers, High power lasers, Semiconductor lasers, Solid state lighting, Solid state lasers, Laser development, Airborne laser technology, Gas lasers
We review the status and applications of a defensive weapon based on high-power lasers in the battlefield. The laser weapon is a novel concept that utilizes a high-power laser beam to traverse the distance into incoming objects at the speed of light and then destroys or disables it. Various types of lasers and configurations are discussed in this review, including gas lasers, solid state lasers, fiber lasers, and the free-electron laser. We discuss various configurations, such as an airborne laser, diode pumped crystals, and disk lasers as well as heat-capacity lasers. Recent applications of ultrafast solid state lasers for nonlethal or low-collateral-damage applications are also presented.
This paper summarizes the physics and experimental results pertaining saturable absorbers based on Cr4+ doped crystals,
in several types of diode-pumped Nd and Yb - doped solid state lasers. The paper focuses on the understanding and on
analyzing the saturation curves of several Cr4+ garnets and other crystals (such as forsterite). Several systems of passively
Q-switched diode-pumped lasers and microlasers were also described, and their performance in terms of average output
power, pulsewidth and repetition rates were described and analyzed. Analytical models which use some measured
physical constants were used to predict the Q-switched laser performance.
We report the operation of passively Q-switched diode-end-pumped Nd:YAG and Nd:YVO4 lasers by employing Cr4+-doped garnets with Ca2+ or Mg2+ as charge compensators. We found that the laser performance improved significantly, mainly in the Nd:YVO4 system when (Cr4+,Mg2+):YAG sample was used as a passive Q-switching. For example, in the Nd:YVO4 and Nd:YAG lasers, the maximum peak power using (Cr4+,Mg2+):YAG saturable absorber was higher by a factor of 8.5 and 2.6, respectively, relative to (Cr4+,Ca2+):YAG. This fact is attributed to better optical quality of the (Cr4+,Mg2+):YAG sample, as a result of improved dopant distribution and reduced internal stresses inside the saturable absorber crystals. Similar passively Q-switched laser performance can be obtained by using other garnets with an open structure, and hence, with low internal stresses, such as (Cr 4+,Ca2+):GGG. We also compared the laser performance of Nd:GdVO4 with the same saturable absorbers and obtained both passive Q-switching and passive mode locking. By using an analytical model with the relevant physical parameters of the laser crystals and saturable absorbers it is possible to optimize the laser performance.
We investigated the CW free-running and repetitive modulation in the kHz frequency domain of a passively Q-switched, diode-pumped Yb:YAG, Yb:GGG and Yb:KYW lasers, by using Cr4+:YAG as a saturable absorber. The results presented here are focused towards the design of a passively Q-switched Yb doped garnets or Yb doped tungstates microlaser. The free-running performance of Yb:YAG, Yb:GGG, Yb:KGW and Yb:KYW were characterized, and experimental parameters such as gain and loss were evaluated. We carried out a fit between our experimental results and an existing numerical model, which relates the experimental and the physical parameters of the ytterbium diode-pumped system to the minimal threshold pumping power. The best performance among the laser crystals was obtained for Yb:YAG laser. A maximum peak power of ≈4.5-kW, at an average output power of 1.32-W, were extracted with of ≈25 % extraction efficiency.
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