Patent ID: 8433169

Claim:
An optical fiber comprising: a core region having a longitudinal axis and a refractive index, and a cladding region surrounding said core region, said core and cladding regions configured to support and guide the propagation of signal light in a fundamental transverse mode in said core region in the direction of said axis, said cladding region including an outer cladding region, a pedestal region having a refractive index higher than that of said outer cladding region, an annular inner trench region disposed between said core region and pedestal region, said inner trench region having a refractive index less than that of said outer cladding region, and said pedestal region being configured to resonantly couple at least one transverse mode of said core region, other than said fundamental mode, to at least one transverse mode of said pedestal region; and an annular outer trench region disposed between said pedestal region and said outer cladding region, said outer trench region having a refractive index less than that of said outer cladding region, wherein the refractive indices of said core region and said pedestal region are within approximately 0.003 of one another.