Tunable integrated photonic devices working at the visible and near infrared (NIR) regions are needed in a variety of applications ranging from consumer market to DoD sector and space. From a large selection of materials which can provide tunability to optical components, phase change materials stand out due to their reliable phase transitions and relatively large change in their optical and electrical properties as they go through crystallographic phase transition. Specifically, Germanium Telluride-based compounds, such as Germanium Telluride (GeTe), exhibit very different optical and electrical properties when they undergo phase transitions. Compared to the more commercialized GST material, GeTe has a much simpler fabrication process, more reliable phase transitions and lower loss at the visible wavelength. Two stable phases of GeTe exist at room temperature: amorphous (a-GeTe) and crystalline (c-GeTe), which have drastically different optical and electrical properties at NIR and noticeable differences in the visible range. These unique properties of GeTe are used in our work to implement components with application in novel displays, reconfigurable metamaterials-based devices, and acousto-optic diffraction grating. This talk goes over some of the fundamental design principles used to overcome the challenges posed by limitations of the material in the NIR regime and shows some of the first-of a kind electro-optical device implemented for space and DoD applications using GeTe.