There are two types of optical fibers based on the refractive index, and those can be divided into two subcategories. Its cladding has a lower index of refraction. Used in telecommunication and internet services. The choice of optical fiber materials and fiber design depends on operating conditions. Fiber Optics is the communications medium that works by sending optical signals down hair-thin strands of extremely pure glass or plastic fiber. In terms of material, the classification is as. Classification by refractive index distribution of optical fiber profile According to the different refractive index distributions of optical fiber profiles, optical fiber can be divided into step-index optical fiber and graded-index optical fiber.