It typically consists of: Optical fiber section – single-mode fiber (SMF) is most common, but polarization-maintaining (PMF) or multimode fiber (MMF) can also be used. Miniature lens – such as a C-lens, aspheric lens, or GRIN lens. What is a Fiber Optic Collimator? Fiber optic collimators (also called fiber-optic collimators) are crucial optical components that convert the diverging output from an optical fiber into a collimated (parallel) beam, or conversely focus light from free space into a fiber. They can also be used in reverse to focus light into a fiber. In essence, a simple collimation lens is all that is needed for this purpose.