Development of new technologies based on optic fiber is one of the most studied topics in photonics branch in recent decades. Advantages offered by optical fibers overcome those offered by other technologies making it the mainstay not only for new advances in technology of telecommunications, but also for developing new applications in sensing technologies. Optical fiber sensors have been widely used in sensing applications of various physical, chemical, and even biological measurements; due to their inherent features such as small size, high resolution, high sensitivity, and immunity to electromagnetic interference [1, 2, 3]. Fiber grating optical technologies, including fiber Bragg gratings (FBG) and long-period fiber gratings (LPFG), have attracted a lot of attention during the past decades. Grating-based sensors (FBG, LPFG) possess high sensitivity and multiplexing capability, these features have allowed their use to sense strain, pressure, temperature, refractive index (RI), polarization, among other variables [4, 3]. Despite all the advantages offered, grating-based sensors are difficult and expensive to manufacture, on top of that most Bragg gratings lose performance near 700 °C [5, 6]. Another sensing technology using optical fibers is based on interferometry. Optical fiber interferometric (OFI) devices operate on the interference between two beams that propagate along different optical paths of a single fiber or simply by two different fibers. Beam splitting and recombining the components are required in any configuration of an OFI device [7]. To date, four typical interferometers including: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac, have been demonstrated in optical fibers. Fiber optics interferometer sensors are able to operate at higher temperatures than grating-based sensors. This feature combined with a high sensitivity, multiplexing capabilities, and an easy and inexpensive fabrication, have made OFI devices widely used for sensing temperature and RI [7]. Most OFI devices found in the literature are refractometers, this means they measure RI of the surrounding medium as an indirect measurement of other variables of interest related to it, such as temperature [6, 8, 9, 10], Viscosity [11], and species concentration [12, 13, 14]. Temperature OFI sensors also apply the thermal expansion undergone by the material of which the optical fiber is made of when temperature changes. This expansion causes a change in the overall length of the fiber which will affect the interference patterns [15]. One of the issues of OFI sensors could exhibit cross-sensitivity. In other words, the response from the device will depend on the RI of the surrounding medium. This situation becomes more complicated in cases where the RI of the external medium changes as temperature changes. It is, therefore, necessary to develop OFI sensors of temperature that are RI insensitive, but that preserve desirable features such as low cost, compactness, and multiplexing abilities. This project aim is then, using numerical computational software, to design OFI sensors for temperature which measurement is RI insensitive.