So, to cut right to the chase, you can generally tell if fiber is multimode or singlemode by examining the cable's jacket color, looking for printed markings on the jacket, checking the connector type, and if all else fails, by measuring the core diameter or using an optical. So, to cut right to the chase, you can generally tell if fiber is multimode or singlemode by examining the cable's jacket color, looking for printed markings on the jacket, checking the connector type, and if all else fails, by measuring the core diameter or using an optical. Choosing the right type of fiber optic cable is essential for reliable and cost-effective network performance. The two main types — Single Mode (SM) and Multimode (MM) — differ in construction, performance, and application. 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. There are two main types of fiber optic cables: single mode and multimode. Fiber optic cables transmit data as pulses of light through. Multimode fiber (MMF) is an optical fiber designed to carry multiple light propagation paths—or modes—simultaneously. This is made possible by its relatively large core diameter, typically 50 or 62. 5 microns, compared to the ~9-micron core in single-mode fiber.