Patent ID: 8472770

Claim:
An optical fiber comprising: a core region having a longitudinal axis, 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 having a refractive index less than that of said core region, an inner cladding region surrounding said core region and having a refractive index less than that of said outer cladding region, a pedestal region having a refractive index approximately equal to that of said outer cladding region, an inner trench region disposed between said inner cladding region and said pedestal region, the refractive index of said inner trench region being much less than that of said outer cladding region, and an outer trench region disposed between said pedestal region and said outer cladding region, said pedestal region having a refractive index greater than the refractive indices of said inner and outer trench regions, 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.