Lasers hosts for

Garnets are important gems, abrasives, microwave systems components, magnetic bubble memories, and laser hosts. For the latter, yttrium aluminum garnet is the most important. It also plays an important role in aircraft turbines where it forms a protective coating on the turbine blades. 

By the sol-gel-process, inorganic glassy and hybrid polymeric materials are accessible at comparatively low temperatures [1], Therefore, organic molecules or dyes can easily be incorporated into the oxide matrix. This combination is especially attractive for the development of the following devices optical filters, solid-state lasers, optical switches, nonlinear optical laser hosts, optical data storage media, and photoconductive devices and films [2]. 

Among the best-known garnets Y3Fe2Fe3012 (Y3Fe5012 yttrium-iron garnet YIG) for its magnetic properties and applications, Y3A15012 (YAG, important laser host material). 

According to spectral-kinetic parameters, the optimal conditions of luminescence excitation and detection, so called selection window (SW) parameters, were calculated in the following way. At optimal for the useful component excitation, the liuninescence spectra, decay time and intensity were determined for this mineral and for the host rock. After that, on the personal computer was calculated the proportion between useful and background signals for the full spectral region for each 50 ns after laser impulse. For calculation the spectral band was simulated by the normal distribution and the decay curve by the mono-exponential function. The useful intensity was multiplied by the weight coefficient, which corresponds to the concentration at which this component must be detected. 

Because the mineral scheelite and the related pyrochlore (Section 6.3.9) are important laser host materials for rare earth metal ions, many such compounds and their doped crystals have been investigated intensively. Compounds with the scheelite structure are given in Table 6.8. 

Selenium oxychloride is not the only inorganic solvent used for liquid lasers, several studies use as solvent phosphorus oxychloride, POCl3 (Blumenthal et al., 1968 Brecher and French, 1969 Brinkschulte et al., 1972). Although this solvent is a worse host for ionic salts due to its lower dielectric constant, it is much more attractive for liquid laser uses since it is far less toxic and corrosive than SeOCl2. The approach for the preparation of POCl3 solutions is slightly... 

The laser scheme is modified when neodymium is placed in other host environments in that the electronic levels have slightly different energies with different stimulated emission cross sections which may vary with the polarization of the stimulating radiation. As an example, Nd in lanthanum beryllate host (Nd BeL), the major laser transition is at 1079 nm and 1070 nm for two different polarizations. YAG is the most common and versatile host for neodymium but glass has advantages for high energy applications such as fusion research. Other crystal hosts such as YAP, YLF and BeL have some unique features. 

CaALiO has a stmctme that is composed of linked, distorted AIO4 tetrahedra and seven-coordinate calcium atoms. It is used in laser materials as a host for Nd +. 

Although the conductivity of the trivalent-ion / ""-aluminas is too low for solid electrolyte applications (e g. batteries, sensors), they have potential use in optics, phosphors, and lasers because they can serve as single crystal or powder hosts for the optically active lanthanide ions. For example, Eu +-/3""-alumina emits red luminescence when excited by UV rays. A Nd +-/3""-alumina single crystal shows luminescent... 

Main group oxides with three-dimensional stmctures or transition metal oxides with d° or d ° configurations are wideband gap materials and are colorless when pure. As such they may serve as transparent optical materials or hosts for such applications as lasers or luminescent materials when properly doped. Others that lack a center of symmetry may have ferroelectric or ferroic properties that make them useful for a variety of device applications. Some of these may have nonlinear optical properties so important to modem communication networks (see Sections 6.3 and 6.5 and see Luminescence and see Ferroelectricity). 

Since Cr is used as an ion in tunable near-infrared lasers, much work has also been done on the excited-state absorption of the Cr ion in lattices where the T2 level is situated below the level (see, e.g., 49). Due to the Jahn-Teller effect a complicated situation arises. It is now possible to suggest criteria for choosing Cr " hosts for which the effect of excited state absorption is minimized. These criteria are a large... 

Delayed emission and shift in frequencies constitute basic features of lasers (which is an acronym for Light Amplification by Stimulated Emission of Radiation) also. Glasses are used as hosts for lasers and Nd laser in phosphate glass hosts has been in wide use (Snitzer, 1989). The principle of operation of Nd laser is shown in Figure 11.12 and typifies a... 

Rare earth aluminates are also important commercially as ceramics and ceramic composites for scintillation applications. The importance of the optical properties of rare earth aluminates is underscored by the used of Nd-doped YAG as a laser host. 

Fig. 12.9 PL and second-order DFB laser spectra for different grating periods for neat thin films of Spiro-60T (a) Spiro-DPVBi (b). The laser threshold energy densities of the neat guest, neat host and an optimized G-H system are compared (c).

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