Lasers polarization characteristics

Spin polarization transfer via SPINOE requires effective adsorption of laser-polarized 2 Xe on the sample under study. Figure 63 shows the - Xe MAS NMR spectra of laser-polarized - Xe adsorbed on fullerenes at 150 K. The spectra exhibit narrow signals at ca 0 ppm due to gaseous xenon and broad signals centered at 100-120 ppm (50-80 ppm wide), characteristic of adsorbed xenon. The intensity of the latter signals is 4-5 times higher for C70 than for Ceo, because the specific surface of the C70 sample was approximately twice the specific surface of Ceo and the mass of the C70 sample was 2.5 times the... 

Fig. 2.31 Different two-photon transitions in an atom, depending on the polarization characteristics e and 2 of the two laser fields...

Fig. 7.22 Schematic of the laser-frequency switching apparatus for observing photon echoes and coherent optical transients. The intracavity ADP crystal is oriented in such a way that it changes the refractive index n and therefore the laser frequency without altering the polarization characteristics of the laser beam when a voltage is applied...

Polarization characteristics of the ASE intensity were measured using a single crystal of BPIT as shown in Figure 10.8a [7]. The polarization angle of the excitation laser ((p x) was changed in the range 90° with respect to the perpendicular using a half-wave plate and the emission spectra were observed as a... 

Since the matrix elements Rik i and Rkf 2 depend on the polarization characteristics of the incident radiation, it is possible to select the accessible upper states by a proper choice of the polarization. While for single-photon transitions the total transition probability (summed over all M sublevels) is independent of the polarization of the incident radiation, there is a distinct polarization effect in multiphoton transitions, which can be understood by applying known selection rules to the two matrix elements in (7.53). For example, two parallel laser beams, which both have right-hand circular polarization, induce two-photon transitions in atoms with AL = 2. This allows, for instance, s — d transitions but not s s transitions. When a circularly polarized wave is reflected back on itself, the right-hand circular polarization changes into a left-hand one and if a two-photon transition is induced by one photon from each wave, only AL = 0 transitions are selected. Figure 7.27 illustrates the different atomic transitions which are... 

Khan AZ, Stanbridge AB, Ewins DJ (2000) Detecting damage in vibrating structures with a scanning LDV. Opt Lasers Eng 32(6) 583-592 Kim SB, Sohn H (2007) Instantaneous reference-free crack detection based on polarization characteristics of piezoelectric materials. Smart Mater Struct 16(6) 2375... 

The population changes aN(J,M) induced by the optical pumping process depend on the intensity Ip of the pump laser, its polarization characteristics, its spectral line profile, and also on possible relaxation processes, such as fluorescence or collision-induced transitions which try to restore the equilibrium population. The rate equation for the depopulation dN (M)/dt of a lower sublevel M is... 

Zak] Ribbons of (Cro.iFeo.9)g5Bi5 composition prepared with spinning and then laser treated were studied with angular elhpsometry. Optical polarization characteristics were obtained. 

The importance of laser light, in brief, is tliat its base characteristics, coherence, spectral and polarization purity, and high brilliance allow us to manipulate its properties. Gain switching [i, 10] and mode locking [16] are prime examples of our ability to very specifically control tire laser output. It is easy to see why lasers are tire ideal sources for optoelectronic applications. 

In order to develop the dyes for these fields, characteristics of known dyes have been re-examined, and some anthraquinone dyes have been found usable. One example of use is in thermal-transfer recording where the sublimation properties of disperse dyes are appHed. Anthraquinone compounds have also been found to be usehil dichroic dyes for guest-host Hquid crystal displays when the substituents are properly selected to have high order parameters. These dichroic dyes can be used for polarizer films of LCD systems as well. Anthraquinone derivatives that absorb in the near-infrared region have also been discovered, which may be appHcable in semiconductor laser recording. 

Figure 10-15. Output vs. input energy characteristic of our laser device. The horizontal dashed curve indicates the zero line. A clear laser threshold behavior at an excitation pulse energy ol 1.5 nJ is observed. Below the lasing threshold only isotropic phololuminesccncc is entitled. Above threshold the device emits low divergence single mode laser emission perpendicular to the surface, as schematically shown in the inset. The laser light is polarized parallel to the grating lines.

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