Patent ID: 9709731
Date: 2017-07-18
CPC Classifications: G02B

Claim:
1. An optical fiber, comprising: a graded-index core and a surrounding cladding, wherein the cladding comprises a ledge surrounding the graded-index core, a down-doped trench surrounding the ledge, and an undoped cladding region surrounding the trench, wherein the core and cladding have a refractive index profile that is structured to support propagation of a spatially multiplexed optical signal comprising a plurality of desired signal-carrying modes, while suppressing undesired modes, wherein the undesired modes comprise leaky modes, comprising modes having respective effective indices that are lower than the cladding index, so as to be unguided, and one or more lossy modes, comprising high-loss guided modes having respective effective indices that are close to the cladding index, wherein the index spacing between the desired mode having the lowest effective index and the undesired mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween, wherein the optical fiber is structured to support nine desired modes, divided into five mode groups: a first mode group comprising the LP wherein the graded-index core has wherein the ledge has wherein the trench has wherein the undoped cladding region has