Backwards compatible multi-core fiber optic cable

A device comprising:

• a first optical core;
• a plurality of other optical cores located around a periphery of said first optical core;
• and
• a cladding surrounding said first optical core and said plurality of other optical cores to form a multi-core optical fiber, wherein said first optical core has a diameter of 50 um, 62.5 um or a fixed value in the range of about 3 um to about 9 um.

A device comprising:

• a centrally located first optical core;
• a plurality of other optical cores located around a periphery of said first optical core;
• and
• a cladding surrounding said first optical core and said plurality of other optical cores to form a multi-core optical fiber;
• and
• a connector attached to said multi-core optical fiber, wherein said first optical core will axially align with a core of a single core fiber when said connector is mated to a port presenting the single core fiber.