Optical phenomena

We now embark on a more fonnal description of nonlinear optical phenomena. A natural starting point for this discussion is the set of Maxwell equations, which are just as valid for nonlinear optics as for linear optics. 

Altliough a complete treatment of optical phenomena generally requires a full quantum mechanical description of tire light field, many of tire devices of interest tliroughout optoelectronics can be described using tire wave properties of tire optical field. Several excellent treatments on tire quantum mechanical tlieory of tire electromagnetic field are listed in [9]. 

Worrall had made similar claims regarding theories of light developed in the seventeenth century and in particular, the case of Fresnel whose dramatic and subsequently confirmed predictions had not been as influential as his accommodation of already known optical phenomena. Meanwhile, Stephen Brush had turned his attention to chemistry and the periodic table, given that this seemed to be a case for which successful predictions made by Mendeleev are widely held to have been the reason for the acceptance of the periodic... 

Microscopy methods based on nonlinear optical phenomena that provide chemical information are a recent development. Infrared snm-frequency microscopy has been demonstrated for LB films of arachidic acid, allowing for surface-specific imaging of the lateral distribution of a selected vibrational mode, the asymmetric methyl stretch [60]. The method is sensitive to the snrface distribntion of the functional gronp as well as to lateral variations in the gronp environmental and conformation. Second-harmonic generation (SHG) microscopy has also been demonstrated for both spread monolayers and LB films of dye molecules [61,62]. The method images the molecular density and orientation field with optical resolution, and local qnantitative information can be extracted. 

A nano-light-source generated on the metallic nano-tip induces a variety of optical phenomena in a nano-volume. Hence, nano-analysis, nano-identification and nanoimaging are achieved by combining the near-field technique with many kinds of spectroscopy. The use of a metallic nano-tip applied to nanoscale spectroscopy, for example, Raman spectroscopy [9], two-photon fluorescence spectroscopy [13] and infrared absorption spectroscopy [14], was reported in 1999. We have incorporated Raman spectroscopy with tip-enhanced near-field microscopy for the direct observation of molecules. In this section, we will give a brief introduction to Raman spectroscopy and demonstrate our experimental nano-Raman spectroscopy and imaging results. Furthermore, we will describe the improvement of spatial resolution... 

Nonlinear optical phenomena, as well as near-field optics, provide us with super resolving capability [20]. The probability of nonlinear optical phenomena is proportional to the number of photons which participate in the phenomenon. For example, the intensity distribution of two-photon excited fluorescence corresponds to the square of the excitation light. Thus, we proposed a combination of the field... 

Tichonov EA, Shpak MT (1979) Nonlinear optical phenomena in organic compounds. Naukova Dumka, Kijiv (in Rus)... 

The adsorption or inclusion of solvent molecules may lead to spectacular optical phenomena, as observed for the trinuclear crystalline gold(i) carbeniate complex [Au(N(Me)=C(OMe)]3.24,255... 

Since almost all optical phenomena at sensing surfaces (e.g. adsorption, fluorescence, luminescence, scatter or refractive index, etc.) can be used for biochemical sensing... 

Two straightforward third-order nonlinear optical phenomena which are used to characterize ft and y are EFISH and THG (2)... 

Butcher, P. N. "Nonlinear Optical Phenomena" Ohio State University Engineering Columbus, 1965-... 

Nonlinear ion traps, 15 662 Nonlinear materials, 14 680 Nonlinear optical materials, 17 442-460 advantage of, 17 448 classification of, 17 443—444 economic aspects of, 17 457-458 photorefractive materials, 17 457 second-order, 17 444r-453 third-order, 17 453—457 Nonlinear optical phenomena, 17 443 Nonlinear optics... 

Brewster, D. (1863). On the structure and optical phenomena of ancient decomposed glass. Philosophical Transactions of the Royal Society of Edinburgh 23 193-204. 

Bredas J-L, Comil J, Beljonne D, Santos DAD, Shuai Z (1999) Excited-state electronic structure of conjugated oligomers and polymers a quantum-chemical approach to optical phenomena. Acc Chem Res 32 267-276... 

Newton (...) assumed that all luminous molecules had two poles analogous to those of a magnet (...). Thus, according to this illustrious man, all luminous molecules possess polarity, and it is this hypothesis which led to the designation of polarization as applied to optical phenomena.]... 

Thin epitaxial layers display a rich variety of X-ray optical phenomena which can be exploited for materials characterisation. Superlattice structures in... 

One result of studying nonlinear optical phenomena is, for instance, the determination of this susceptibility tensor, which supplies information about the anharmonicity of the potential between atoms in a crystal lattice. A simple electrodynamic model which relates the anharmonic motion of the bond charge to the higher-order nonlinear susceptibilities has been proposed by Levine The application of his theory to calculations of the nonlinearities in a-quarz yields excellent agreement with experimental data. 

Another important optical phenomena that relies on light interference and diffraction is holography, the process by which holograms (interference patterns) are produced. Whilst holograms are best known for the reproduction of near perfect 3D images of an object in the graphic arts, they also find apphcations in newer areas such as laser eye protection, LCDs, diffractive optical elements, optical processing... 

Iridescence is the colour produced by the phenomena of light interference and diffraction involves these two optical phenomena in combination with reflection. 

We will see that a number of important optical phenomena are functions of the wavelength of light. This is probably a good time to review the various categories... 

Light is absorbed by two basic mechanisms electronic polarization and electronic excitation. Electronic polarization and its effect on refractive index were described in the previous section and will not be elaborated npon here. The process of electronic excitation is an important one, however, and has implications to a nnmber of optical phenomena such as lasing and luminescence. 

Although we admit that these effects must surely appear in small particles, we cannot countenance the uncritical invocation of vague and esoteric quantum size effects, as is sometimes done, to dispose of optical phenomena in small particles that are not understood. Often the correct interpretation may be much simpler particle shape, for example, which we shall discuss in Sections 12.3 and 12.4. Our best advice, based on calculations (Martin, 1973 Chen et... 

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