Optical fiber transmission is based on the principle of total internal reflection, where light signals are transmitted through a thin glass or plastic fiber with a core and cladding. In fiber-optic communication, a single-mode optical fiber, also known as fundamental- or mono-mode, is an optical fiber designed to carry only a single mode of light - the transverse mode. Modes are the possible solutions of the Helmholtz equation for waves, which is obtained by combining. What is the condition for single-mode guidance in step-index fibers? How does the mode radius change with core size for a constant numerical aperture? How much do mode intensity profiles extend beyond the fiber core? What factors influence efficient light launching into a single-mode fiber? What. To meet demand of increase in the telecommunication data transmission. Higher bandwidth (extremely high data transfer rate). For abrupt fiber, n1 is the refractive index of the core medium, n2 is the.