An optical fiber comprising: a core region having a longitudinal axis, said core region including: an inner core region (12.1) having an inner core region index of refraction (n core) and an inner core width, wherein 8 μm ≤ D ≤ 11μm, and an annular outer core region (12.2) surrounding said inner core region (12.1), the outer core region (12.2) having an outer core region index of refraction (n shlf) and an outer core region thickness (t shlf), wherein n shlf < n core and t shlf < D, wherein 1.0 μm ≤ t shlf ≤ 4.0 μm and a cladding region surrounding said core region, said core and cladding regions (12, 14) 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 (14.4) having an outer cladding region index of refraction (nout), wherein 0.003 ≤ (n core - n out) ≤ 0.006, a pedestal region (14.1) having a pedestal index of refraction (n ped), said pedestal region (14.1) being configured to resonantly couple at least one other transverse mode of said core region to at least one transverse mode of said pedestal region (14.1), wherein n ped > n out, and wherein n ped is comparable to n core such that |n core - n ped | < 0.003, and an annular inner trench region (14.2) disposed between said core region and pedestal region (14.1), said inner trench region (14.2) having an inner trench index of refraction (n tri), wherein n tri < n out, wherein |n tri - n core | > 0.007; an annular outer trench region (14.3) disposed between said pedestal region (14.1) and said outer cladding region (14.4), said outer trench region (14.3) having an outer trench index of refraction (n tro), wherein n tro < n out and |n tro - n core | > 0.007, and wherein a) 0.5 < [(n tri -n out)t tri]/[(n tro -n out)t tro] < 2.0, wherein t tri is the thickness of the annular inner trench region (14.2) and t tro is the thickness of the annular outer trench region (14.3), and/or b) 0.4 μm ≤ t tri ≤ 9.2 μm and 6.8 μm ≤ t tro ≤ 12.1 μm. a core region having a longitudinal axis, said core region including: an inner core region (12.1) having an inner core region index of refraction (n core) and an inner core width, wherein 8 μm ≤ D ≤ 11μm, and an annular outer core region (12.2) surrounding said inner core region (12.1), the outer core region (12.2) having an outer core region index of refraction (n shlf) and an outer core region thickness (t shlf), wherein n shlf < n core and t shlf < D, wherein 1.0 μm ≤ t shlf ≤ 4.0 μm and an inner core region (12.1) having an inner core region index of refraction (n core) and an inner core width, wherein 8 μm ≤ D ≤ 11μm, and an annular outer core region (12.2) surrounding said inner core region (12.1), the outer core region (12.2) having an outer core region index of refraction (n shlf) and an outer core region thickness (t shlf), wherein n shlf < n core and t shlf < D, wherein a cladding region surrounding said core region, said core and cladding regions (12, 14) 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 (14.4) having an outer cladding region index of refraction (nout), wherein 0.003 ≤ (n core - n out) ≤ 0.006, a pedestal region (14.1) having a pedestal index of refraction (n ped), said pedestal region (14.1) being configured to resonantly couple at least one other transverse mode of said core region to at least one transverse mode of said pedestal region (14.1), wherein n ped > n out, and wherein n ped is comparable to n core such that |n core - n ped | < 0.003, and an annular inner trench region (14.2) disposed between said core region and pedestal region (14.1), said inner trench region (14.2) having an inner trench index of refraction (n tri), wherein n tri < n out, wherein |n tri - n core | > 0.007; an annular outer trench region (14.3) disposed between said pedestal region (14.1) and said outer cladding region (14.4), said outer trench region (14.3) having an outer trench index of refraction (n tro), wherein n tro < n out and |n tro - n core | > 0.007, and an outer cladding region (14.4) having an outer cladding region index of refraction (nout), wherein 0.003 ≤ (n core - n out) ≤ 0.006, a pedestal region (14.1) having a pedestal index of refraction (n ped), said pedestal region (14.1) being configured to resonantly couple at least one other transverse mode of said core region to at least one transverse mode of said pedestal region (14.1), wherein n ped > n out, and wherein n ped is comparable to n core such that |n core - n ped | < 0.003, and an annular inner trench region (14.2) disposed between said core region and pedestal region (14.1), said inner trench region (14.2) having an inner trench index of refraction (n tri), wherein n tri < n out, wherein |n tri - n core | > 0.007; wherein a) 0.5 < [(n tri -n out)t tri]/[(n tro -n out)t tro] < 2.0, wherein t tri is the thickness of the annular inner trench region (14.2) and t tro is the thickness of the annular outer trench region (14.3), and/or b) 0.4 μm ≤ t tri ≤ 9.2 μm and 6.8 μm ≤ t tro ≤ 12.1 μm. a) 0.5 < [(n tri -n out)t tri]/[(n tro -n out)t tro] < 2.0, wherein t tri is the thickness of the annular inner trench region (14.2) and t tro is the thickness of the annular outer trench region (14.3), and/or b) 0.4 μm ≤ t tri ≤ 9.2 μm and 6.8 μm ≤ t tro ≤ 12.1 μm.