In contrast, multimode fiber uses a much larger core, commonly 50 or 62. 5 micrometers, allowing many spatial modes to propagate simultaneously. Singlemode and the latest innovations and developments in multicore, hollow core, and bend-insensitive fiber. I remember the researchers at Bell Labs who introduced me to fiber optics in the late 1970s telling me. Multimode Fiber (MMF) has a core diameter, typically 50–100 micrometers, has ability to transfer multiple modes of light through the fiber core, uses lower-cost electronics (LED, VCSEL) operates at the 850 nm and 1300 nm wavelength and is used for short distance interconnections (up to 550m). Single mode fiber optic cable is made up of a small diameter glass or plastic core surrounded by cladding, which is a layer of reflective material. This small diameter core, typically around 9 microns in diameter, allows only one mode of light to pass through, resulting in a narrower beam of light. Multi-mode optical fiber is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. Multi-mode links can be used for data rates up to 800 Gbit/s. In this way the guided light is largely decoupled from the solid fibre material, greatly reducing material contributions to fibre non-linearity, damage thresholds and absorption [1,2]. Let's take a brief look at both types of fiber.