Optical frequency doubling, molecular

According to (3.12), the Raman scattering cross section increases considerably if the laser frequency co matches a transition frequency coij of the molecule (resonance Raman effect) [310, 311]. With tunable dye lasers and optical frequency doubling this resonance condition can often be realized. The enhanced sensitivity of resonant Raman scattering can be utilized for measurements of micro-samples or of very small concentrations of molecules in solutions, where the absorption of the pump wave is small in spite of resonance with a molecular transition. 

New properties such as nonlinear optical activity (frequency doubling) of the nanofibers are created due to intrinsic nonzero hyperpolarizability of the nonsymmetrically substituted molecular building blocks. 

In this review, the focus is on electro-optic materials. Such materials are members of the more general class of second-order nonlinear optical materials, which also includes materials used for second harmonic generation (frequency doubling). The term second-order derives from the fact that the magnitude of these effects is defined by the second term of the power series expansion of optical polarization as a function of applied electric fields. The power series expansion of polarization with electric field can be expressed either in terms of molecular polarization (p Eq. 1) or macroscopic polarization (P Eq. 2)... 

If the molecule or the solid has a center of inversion symmetry, then the permanent dipole moment m0 vanishes, as do the even-rank tensors j8 and 8 and the even-rank tensors y<2), y<4), and All matter, with or without a center of inversion symmetry, has nonzero values for the odd-rank molecular tensors a and y, and all odd-rank tensors ytensor components is vastly reduced. The components have values that depend seriously on the frequency of the electromagnetic radiation used to probe them. A practical application of nonlinear optics is frequency-doubling of the high-powered... 

Li. D.. Ratner. M., Marks, T.J. Molecular and macromolecular nonlinear optical materials. Probing architecture/electronic structure/frequency doubling relationship via SCF-LCAO MECI ir electron formalism. J. Am. Chem. Soc. 110, 1707-1715 (1988)... 

Figure 2-2. A non-linear optical material, ammonium dihydrogen phosphate, displaying second-harmonic generation, the frequency doubling of light (infrared to blue). The origin of this physical phenomenon is entirely dependent on ionic displacement or molecular charge-transfer (see color plate...

Frequency doubling, or SHG, as illustrated in Figure 1, is of keen interest as a means of generating new laser sources. Frequency doubling of low power diode lasers from the red or infrared into the blue comprise a prime commercial application. Device outlets include higher capacity optical storage devices, as well as more sensitive laser printers and copiers. The objective is to increase not only the molecular response p, but of course the material response Be-... 

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