Optical structuring

In contrast to metals, most studies have concentrated on insulators and semiconductors where the optical structure readily lends itself to a straightforward interpretation. Within certain approximations, the imaginary part of the dielectric fiinction for semiconducting or insulating crystals is given by... 

Polarized light photomicrographs were taken of the green and calcined cokes, as well as their corresponding test graphites. The untreated extract cokes are characterized by very small amsotropic domains on the order of 3 microns or less. This type of optical structure is believed to be highly desirable for nuclear graphite applications. 

Headache and compromised visual function (loss of peripheral vision and blurred vision) caused by the actual tumor mass and its close proximity to the optic structures. 

The simplest Integrated Optical structure is the slabguide consisting of three layers of which the middle one has to have the largest refractive index (see Figure 2). 

Many classical optical sensing principles, which are well known from free space optics can be implemented in integrated optical structures, while integrated optics at its turn can act as source of new principles. Many types of integrated optical sensors have been investigated and demonstrators have been realized, mostly at universities and other research institutes. And also at... 

Optical circuits will not simple mimic electronics, but will exploit in a complementary way the unique phenomena offered by light. For example THz bandwidth amplification is straightforward in optical structures with... 

Chu, S.T. and Chaudhuri, S.K., 1989, A finite-difference time domain method for the design and analysis of guided-wave optical structures, J. Lightwave Technol. 7 2033-2038. 

Melloni, A., Morichetti, F., and Martinelli, M., 2003, Linear and nonlinear pulse propagatiou in coupled resonator slow-wave optical structures. Opt. Quantum Electron. 35 365-379. 

Consider a one-dimensional optical structure that consists of nonlinear layers. The structure is illustrated in Fig. 1. Assuming no field variation in the X and z directions and the convention exp(icot) for the time dependence of the fields, Maxwell s equations take the form... 

To demonstrate the method an example of a slow-wave optical structure is modelled. Such structures consist of a cascade of directly coupled optical resonators in order to enhance the nonlinear effects. The structure used here was recently defined within Working Group 2 of the European Action COST Pll (http //w3.uniromal.it/energetica/slow waves.doc). One period of the structure consists of one-dimensional Fabry-Perot cavity placed between two distributed Bragg reflectors (DBR) and can be described by the sequence... 

A. Melloni, F. Morichetti, and M. Martinelli, "Linear and nonlinear pulse propagation in coupled resonator slow-wave optical structures," Opt. Quant. Electron. 35, 365-379 (2003). 

S. Tanev, D. Feng, V. Tzolov, and Z. J. Jakubczyk, Finite-difference time-domain modeling of complex integrated optics structures. Technical Digest, Integrated Photonics Research Conference Edition (Optical Society of America, Washington, 1999), pp. 202-204. 

The electronic structure of fluorenes and the development of their linear and nonlinear optical structure-property relationships have been the subject of intense investigation [20-22,25,30,31]. Important parameters that determine optical properties of the molecules are the magnitude and alignment of the electronic transition dipole moments [30,31]. These parameters can be obtained from ESA and absorption anisotropy spectra [32,33] using the same pump-probe laser techniques described above (see Fig. 9). A comprehensive theoretical analysis of a two beam (piunp and probe) laser experiment was performed [34], where a general case of induced saturated absorption anisotropy was considered. From this work, measurement of the absorption anisotropy of molecules in an isotropic ensemble facilitates the determination of the angle between the So Si (pump) and Si S (probe) transitions. The excited state absorption anisotropy, rabs> is expressed as [13] ... 

It is my contention that the optical and physical properties and the optical structure produced during the destructive distillation or thermal decomposition of vitrinite is closely related to mode of carbonization and, in the case of pitch, is intimately related to the method of pitch preparation. For instance, a pitch may be produced from a high or low temperature tar, from a primary cooler tar, or from a flushing liquor tar. In addition, it may be air blown, thermally or chemically treated, straight distilled, or cut back, just to mention a few. Under similar carbonization conditions almost any one of these pitches will produce a coke which has certain characteristics that are related to the parent pitch. Even pitches similarly processed from the tar can differ in the content of quinoline- and benzene-insoluble material and P-resin, and can contain more than one distinct liquid phase. None of these points of difference has been discussed by Dr. Taylor or even recognized in the preparation. To interpret the structure of pitch coke divorced from a knowledge of the pitch source and/or carbonization conditions can lead to erroneous conclusions. These are pertinent data omitted by the authors. 

By incorporating these three material phenomena for chemical measurements with fiber optic structures creates a basis for a fiber optical chemical sensor or FOCS. Two classes of FOCS have been reported in the literature ... 

The electronic structure is similar within each group as far as optical properties are concerned. For example, at the photon energy used in our experiments the optical response of the noble metals is entirely due to intraband optical transitions [22, while that of Ti, Zr, and Hf is dominated by interband transitions [23,24], The optical structures of Ni and Pd are more complicated, and both interband and intraband transitions can contribute [24,25. This interpretation is supported by the observation that the signals of largest and smallest magnitude occur in Zr and Ag, respectively. 

Before optical structure recognition methods can be applied to a document, the chemical images in the document must be identified and separated from the rest of the document so subsequent processing stages can operate exclusively on the... 

Though far from perfect, at least some of the various recognition methods described in this chapter can yield impressive recognition results. Figure 4.20 shows some structure diagrams that are correctly interpreted by optical structure recognition within a few seconds. Manual reproduction of these structures would require considerably more time and be error prone. 

---