Patent ID: 8374472

Claim:
An optical fiber comprising: a core region having a longitudinal axis, said core region including: an inner core region, and an annular outer core region surrounding said inner core region, the refractive index of said outer core region being less than that of said inner core region and the thickness of said outer core region being less than a width of said inner core region, 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 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 inner trench region disposed between said core region and pedestal region, said inner trench region having a refractive index less than that of said pedestal region.