Difração em fibra de cristal fotônico como metodologia para medição de índice de refração

Abstract

This work describes the development, results and application of a technique for the evaluation of phase change processes in a fluid of interest, by spectrographic analysis, using single-mode Slim core wide area mode and polarization-maintaining PCF, filled with water. Changes in the physical state of the liquid from liquid to solid, it becomes possible to measure the spectrum changing of the transmitted portion of the light that crosses the fiber. The motivation of this research was to evaluate a new method to infer the refractive index of substances when phase changes occur through spectrographic analysis. Variations on the physical state of the substance change the transmittance by the variation of diffraction in the PCF at certain wavelength ranges and, whose property, can be harnessed for the development of sensors for phase shift detection. This measurement methodology, as well as the results obtained, will assist the investigation of substances in frozen forms and their formation processes, in order to monitor their appearance conditions and, then, it could be possible to activate dissolution devices for them. The tests performed made it quite clear that there is an effective wavelength range for measurement and the conditions for the freezing phenomenon occurrence and others associated, such as transmittance increasing and "cut-off' wavelength variation of the substance filled in the holes.