Patent ID: 9671552
Date: 2017-06-06
CPC Classifications: G02B,H04J

Claim:
1. An optical fiber, comprising: a core and a cladding surrounding the core, wherein the core and cladding have a refractive index profile that is structured to support propagation of a plurality of desired signal-carrying modes, while suppressing undesired modes, wherein the core comprises a graded-index core, wherein the cladding comprises a ledge abutting the core, wherein the cladding further comprises a down-doped trench abutting the ledge, and an undoped cladding region abutting the trench, wherein the core, and cladding are configured to support propagation of a spatially-multiplexed optical signal comprising a plurality of desired modes, while suppressing undesired modes, wherein the core and surrounding cladding are configured such that undesired modes have respective effective indices that are close to or less than the cladding index so as to result in leaky modes that leak into the outer cladding region, wherein the index spacing between the desired mode having the lowest effective index and the leaky mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween, and wherein the optical fiber is a few-mode fiber that carries 9 desired signal-carrying modes and the maximum relative refractive index of the core is less than or equal to approximately 0.5%.