Patent ID: 8406594

Claim:
An optical fiber adapted for suppression of higher order modes (HOM) and/or for guiding light in a narrow spectral wavelength range, said optical fiber comprising: an axial direction, a cross section perpendicular to said axial direction, and a core region extending along said axial direction, said core region being adapted to guide an optical signal; a cladding region surrounding said core region, said cladding region comprising an inner cladding region comprising an inner cladding basis material in which inner cladding features extending along said axial direction are defined, said inner cladding features comprising a plurality of first inner cladding features comprising a first material and having a first refractive index profile, a first cross sectional shape and a first normalized frequency parameter relative to said inner cladding basis material, wherein said plurality of first inner cladding features forms a first cross sectional extending optical resonant structure connecting said core region to a first light sink, wherein said inner cladding features further comprises a plurality of second inner cladding features comprising a second material and having a second refractive index profile, a second cross sectional shape and a second normalized frequency parameter relative to said inner cladding basis material, wherein said plurality of second inner cladding features forms a second cross sectional extending optical resonant structure connecting said core region to a second light sink, and wherein either said first refractive index profile differs from said second refractive index profile; and/or said first cross sectional shape differs from said second cross sectional shape, and/or said first normalized frequency parameter differs from said second normalized frequency parameter, and wherein said inner cladding features further comprises a plurality of third inner cladding features that comprise a third material and have a third refractive index profile and a third cross sectional shape, wherein said third inner cladding feature comprises a low index region, and wherein said low index region comprise a void.