La fotónica se ha estudiado por más de dos décadas con el fin de trabajar en la construcción, desarrollo y manipulación de la luz especialmente de estructuras cristalinas a escala nanométrica para ser empleadas en las telecomunicaciones, computación, celdas solares hasta biosensores, y demás aplicaciones que han sido de gran utilidad en la actualidad como lo es en la biomédica. Por esta razón, en el presente artículo, expone un estudio retrospectivo de los cristales fotónicos, con el propósito de dejar como precedente un estado del arte que manifieste los fundamentos teóricos, aplicativos de cristales fotónicos en tratamientos médicos. Así mismo, se expone de manera descriptiva y comparativa el estudio de los cristales fotónicos según la física desde la perspectiva electromagnética por medio de las leyes de maxwell con una visión macroscópica del comportamiento de los cristales fotónicos y desde el punto de vista de la optoelectrónica. Por último, se expresan conclusiones cualitativas de la implementación de cristales fotónicos en tratamiento médicos.

Quantitative compositional information can be extracted from high-resolution Z-contrast images by comparison of simulated and experimental images. We developed a phenomenological method to determine quantitatively the composition of a material with atomic column spatial resolution directly from the analysis of local integrated intensities of aberration-corrected Z-contrast experimental images [1]. In this work we apply this method to high-resolution aberration-corrected Z-contrast images acquired at 100kV with a dedicated Nion UltraSTEM scanning transmission electron microscope, which is equipped with a Nion aberration-corrector and a Gatan Enfina EELS detector. Specimens for Z-contrast imaging were prepared by mechanical thinning and Ar + ion milling using a Precision Ion Polishing System (PIPS). A beam energy less than 3.5 kV has been selected to reduce amorphisation of the sample. As a final step, the sample was introduced in a Fischione ion mill at 12 o and 0.5 kV to reduce surface damage. The thickness of the analyzed region was determined from the analysis of the corresponding spatially resolved low-loss EELS signal [2].In order to estimate the composition in each column, we follow a procedure previously published [1] in which the first step is to detect pixels with the local intensity maxima associated; for that purpose we apply the Peak Pairs software [3]. Once these maxima intensity pixels are located, it is straightforward, with the help of the image processing software, to measure the intensities integrated within a selected area of the projected unit cell. In order to decide the best integration area, several measurements have been taken using different integration areas. A certain area of integration was finally selected that gives normalized integrated intensity ratios R as shown in equation (1). R values were determined following the procedure described in ref.[1], but taking whole unit cells in the present study. R values show some advantages when they are defined in this way: (a) R depends almost linearly on the composition, (b) R has a very low dependence on specimen thickness over a convenient thickness range, (c) R values are almost unaffected by surrounding dumbbells so that the signal is essentially due to just the atoms contained within the selected atomic column. R i = I column /I substrate (1) 1728