Lasers Characteristics

Ayyangar NR, Srinivasan KV, Daniel T (1991) Polycyclic compounds Part VII. Synthesis, laser characteristics and dyeing behaviour of 7-diethylamino-2H-l-benzopyran-2-ones. Dyes Pigm 16 197-204... 

The special laser characteristics outlined in the last chapter indeed make the laser a very attractive light source for spectroscopists and many of the applications discussed below were proposed soon after the first successful operation of an optical maser " . Meanwhile many laboratories are working in this field, and a selection from the numerous spectroscopic experiments will be presented in the following sections. 

Yariv and colleagues (74) studied the fluorescence and laser characteristics of praseodymium in calcium tungstate. For the G4 metastable state with a doping level of 0.5 per cent, they report a fluorescent decay time of 50 /nsec. This data was taken at 77°K and was obtained using an analog technique (74). 

The procedure that we propose to enhance the concentration of a particulap enantiomer when starting with a racemic mixture, that is, to purify the mixture) is as follows [259], The mixture of statistical (racemic) mixture of L and irradiated with a specific sequence of three coherent laser pulses, as described below. These pulses excite a coherent superposition of symmetric and antisymmetric vibrational states of G. After each pulse the excited system is allowed to relax bg t to the ground electronic state by spontaneous emission or by any other nonradiativ process. By allowing the system to go through many irradiation and relaxatio cycles, we show below that the concentration of the selected enantiomer L or can be enhanced, depending on tire laser characteristics. We call this scenario lat distillation of chiral enantiomers. 

In order to determine the influence of various discharge processes on laser characteristics, gas temperature, electron density, and average electron energy were taken as independent modeling parameters [8]. In reality this cannot be achieved under ordinary dc discharge conditions. However, by using this approach it is possible clearly to identify the discharge parameters that have major influence on laser performance characteristics. 

In the first part, emphasis will be put on the linear optical properties of dielectric media doped with noble metal nanoparticles. Indeed, the study of the linear response is definitely needed to further explore the nonlinear one. We will then introduce the fundamentals of the theoretical tools required to understand why and how people inquire into the third-order nonlinear properties of nanocomposite materials. In the second part, experimental results will be presented by first examining the different nonlinear optical phenomena which have been observed in these media. We will then focus on the nanoparticle intrinsic nonlinear susceptibility before analysing the influence of the main morphological factors on the nonlinear optical response. The dependence of the latter on laser characteristics will finally be investigated, as well as the crucial role played by different thermal effects. 

Fig. 12.10 PL and first-order DFB laser spectra for different grating periods based on a Spiro-60T thin-film doped with 1.1% of Spiro-DPVBi (a) and laser characteristics for a sample at a wavelength of 478 nm.

Fig. 12.15 Absorption, photoluminescence and ASE spectrum of MeLPPP (a) and spectrum of first-order DFB laser structure and laser characteristic (inset) (b).

Srio(V04)6F2 Mn showed ideal laser characteristics with emission at 1160 nm. Mn doped into Sr fluorapatite and other phosphates for laser applications has also been examined by Copobianco et al. (1992), and the luminescence properties of Mn in a... 

Shoji I, Kurimura S, Sato Y, Taira T, Ikesue A, Yoshida K (2000) Optical properties and laser characteristics of highly Nd3 -doped Y3AI5O12 ceramics. Appl Phys Lett 77 939-941... 

Dong J, Ueda K, Yagl H, Kaminskii AA, Cai Z (2009) Comparative study the effect of Yb concentrations on laser characteristics of Yb YAG ceramics and crystals. Laser Phys Lett 6 282-289... 

Recently, an extensive effort has been made to improve the laser characteristics for the industrial application for laser lithography. Improvement in the high-repetition rate frequency, high average power, narrow linewidth, and operational long gas lifetime continues. 

Raju, B. B. and Varadarajan, T. S. 1995. Photophysical properties and energy transfer dye laser characteristics of 7-diethylamino-3-heteroaryl coumarin in solution. Laser Ghent. 16(2) 109-120. 

The novel electronic and photonic properties of thiophene-based oligomers have been described, using examples of FET device applications and laser characteristics. Thiophene-based oligomers were shown to be one of the most promising materials. 

Laser-welding method Type of laser Characteristics... 

Figure 14.5 Absorption signalofthe RbOj-line, using a tuneable diode Laser. Top linearabsorption signal, revealing th e diode s noise and amplitude variations with wavelength. Bottom same absorption, but normalized forthe diode laser characteristics using a balanced detector minor signal features (here diode laser side bands) are revealed due to the largely improved S/Nratio...

The quantitative aspects of LIBS even for laboratory applications may be considered its Achilles heel, first due to the complex nature of the laser-sample interaction processes, which depends upon both the laser characteristics and the sample material properties, and second due to the plasma-particle interaction processes, which are space and time dependent. All those parameters influence strongly on plasma conditions and, consequently, on emission lines intensities. Consequently it may sound correct, that LIBS is a mix of great potential and severe limitation, that one of the major problems that precludes its more quantitative use is a lack of reproducibility of spectra at a given wavelength on a shot to shot basis, and that the sensitivity remains modest, precision mediocre and matrix dependence strong (Hahn and Omenetto 2012). 

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