Photonic Crystal Fibers (PCF) have drawn a lot of interest due to their potential to produce a distinctive spectrum of optical properties that are just not feasible in common fiber types, whereas PCF can work in both conditions if the refractive index (RI) of the core is higher than the refractive index of the cladding In this case light is guided through total internal reflection (TIR), while in the second condition ,the refractive index (RI) of the core is lower than the refractive index of the cladding, the light is guided through a photonic bandgap effect, which is not possible with conventional fibers. The surface plasmon resonance (SPR) is used in the sensor design. In this overview, an analysis of current advancements in photonic crystal fiber sensor design for sensing applications is presented, as also the effect of gold and silver nanoparticles and other types of material used to coat optical crystal fibers for sensors, the focus of this article uses of PCF for various sensing applications. such as thermal sensors, gas sensors, and biosensors. These PCFs are available in two types solid core and hollow core. Solid core photonic PCF has traditionally been utilized for sensing applications because the cladding channels can be filled with gas or liquid, acting as a useful form of evanescent wave sensing and also can coat the outer surface with plasmonic material depending on the surface plasmonic resonance phenomenon. Hollow core PCF delivers significant gains because of the presence of samples in the core. Hollow core PCF is used for sensor purposes by s filling the core with different types of liquid or gases where the majority of the light is contained, increasing the interaction between light and matter. Due to the exceptional properties that such photonic crystal fiber can give, more sensors are anticipated to be created in the future. The development of various optical sensing methods, their advantages, disadvantages, and potential for point-of-care applications are all thoroughly covered.
