All-fiber optical sensors have established themselves in the market for a decade. Among different categories of these sensors is the intensity-based type whose advantages make it suitable for many practical applications. Frustrated Total Internal Reflection (FTIR) is a phenomenon that shows a great potential to be used as a transduction mechanism in this type of sensors. Although physical interpretation of the phenomenon itself is rather complicated, it can be mathematically formulated in a non-extensive manner. The first attempt is to build a physical understanding of the phenomenon as well as a simple mathematical model based on planar waves. Then, it will be expanded it to waves inside a waveguide structure like optical fibers in a concrete way based on computer simulations and actual experiments, a task that has never been done before. This would make it possible to address the practical issues involved afterwards. Again, the obtained experimental results as well as simulations help analyze advantages and disadvantages of our basic structure and move on to design a practically viable all-fiber FTIR sensor. A prototype vacuum pressure sensor has been designed and tested to show the potential in this category of optical sensors. Some other applications are also briefly discussed to give us a good feeling of the restrictive problems and future prospective of the ongoing related research. / Master of Science