Suppressing surface modes in fibers

An optical fiber having an axial cross section, the axial cross section having an axial center, the axial cross section further having a reference direction that extends radially in one direction from the axial center, the optical fiber comprising:

• a hollow core located substantially at the axial center;
• and
• a cladding matrix surrounding the hollow core, the cladding matrix comprising:
• cladding holes having cladding-hole properties;
• struts located between cladding holes, the struts having substantially uniform properties;
• and
• n non-uniform modified holes disposed in the cladding matrix at various radial distances from the axial center, n being an integer multiple of 6, the non-uniform modified holes further being disposed in the cladding matrix at approximately sixty degree (60°) angle increments from the reference direction, wherein the non-uniform modified holes have modified properties that differ from the cladding-hole properties, and wherein at least one modified hole has at least one modified property that differs from that of a second modified hole.