The resulting solutions are the linearly polarized (LP) modes, denoted LP ℓ m , whose transverse fields are well approximated as having a nearly uniform linear polarization across the core. It details the LP ℓ m notation and clarifies that this simplified scalar treatment assumes a. In fiber optics, polarization-maintaining optical fiber (PMF or PM fiber) is a single-mode optical fiber in which linearly polarized light, if properly launched into the fiber, maintains a linear polarization during propagation, exiting the fiber in a specific linear polarization state; there is. I present here quickly the expression of the modes of a step-index multimode fiber and the so-called linearly polarized modes, that are convenient for manipulation using shaping techniques. This post is largely inspired by Chapter 3 of [Fundamentals of Optical Waveguides] by K. The. 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.