Photonic lantern structures and devices

An apparatus comprising:

• a first multi-core optical fiber;
• a second multi-core optical fiber;
• and
• a coupler optically connecting the first multi-core optical fiber to the second multi-core optical fiber,
• wherein the first multi-core optical fiber comprises N cores and the second multi-core optical fiber comprises M>N cores, where M and N are positive integers.

An apparatus comprising:

• a first multi-core optical fiber;
• a second multi-core optical fiber;
• a first coupler optically connecting the first multi-core optical fiber to the second multi-core optical fiber;
• a second coupler coupled to the second multi-core optical fiber;
• and
• an intermediate optical fiber connecting the first coupler to the second coupler,
• wherein the intermediate optical fiber is a multi-mode optical fiber.

An apparatus comprising:

• a multi-core input fiber;
• a multi-core output fiber;
• at least one coupler, optically connecting the multi-core input fiber to the multi-core output fiber, to couple a first beam from a first input core into the multi-core input fiber to a first output core in the multi-core output fiber;
• and
• a detector, in optical communication with the multi-core output fiber, to sense light emitted by the first output core;
• a controller, operably coupled to the detector, to determine a phase adjustment to the first beam, the phase adjustment causing the at least one coupler to couple the first beam from the first input core to a second output core in the multi-core output fiber;
• and
• a phase modulator, in optical communication with the first input core, to impart the phase adjustment to the first beam.