Double Risley prism pairs for optical beam steering and alignment

An optical communication apparatus comprising:

• an input optical fiber that transmits a first light beam;
• an output optical fiber that transmits a second light beam;
• a first Risley prism pair disposed in an optical path between said input optical fiber and said output optical fiber;
• and
• a second Risley prism pair disposed in said optical path between said first Risley prism pair and said output optical fiber;
• a first actuator for said first Risley prism pair, wherein said first actuator adjusts a first deflection angle of said first Risley prism pair so that said first Risley prism pair steers said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• a second actuator for said second Risley prism pair, wherein said second actuator adjusts a second deflection angle of said second Risley prism pair so that second Risley prism pair aligns said second light beam to be incident on a first outside prism face of said first Risley prism pair, thereby forming an aligned optical path between said input optical fiber and said output optical fiber.

A 3-dimensional optical cross-connect switch comprising:

• an input array of input optical fibers comprising at least one input optical fiber that transmits a first light beam;
• an output array of output optical fibers comprising at least one output optical fiber that transmits a second light beam;
• a plurality of Risley prism pairs wherein:
• each of said input optical fibers has a corresponding input Risley prism pair in said plurality of Risley prism pairs, and
• each of said output optical fibers has a corresponding output Risley prism pair in said plurality of Risley prism pairs;
• a first Risley prism pair of said plurality of Risley prism pairs, corresponding to said at least one input optical fiber, and disposed in an optical path between said at least one input optical fiber and said at least one output optical fiber;
• and
• a second Risley prism pair of said plurality of Risley prism pairs, corresponding to said at least one output optical fiber, disposed in said optical path between said first Risley prism pair and said at least one output optical fiber;
• a first actuator for said first Risley prism pair, wherein said first actuator adjusts a first deflection angle of said first Risley prism pair;
• a second actuator for said second Risley prism pair, wherein said second actuator adjusts a second deflection angle of said second Risley prism pair
• a controller that:
• receives a first feedback signal from said first actuator wherein said first actuator includes a first position sensor that senses a first prism position of said first Risley prism pair and provides said first feedback signal to said controller;
• provides a first control signal to said first actuator that adjusts said first deflection angle so that said first Risley prism pair steers said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• receives a second feedback signal from said second actuator wherein said second actuator includes a second position sensor that senses a second prism position of said second Risley prism pair and provides said second feedback signal to said controller;
• provides a second control signal to said second actuator that adjusts said second deflection angle so that said second Risley prism pair aligns said second light beam to be incident on a first outside prism face of said first Risley prism pair, thereby forming an aligned optical path between said input optical fiber and said output optical fiber wherein a signal light beam is transmitted over said aligned optical path between said at least one input optical fiber and said at least one output optical fiber.

An optical communication system comprising:

• a plurality of nodes wherein at least one node of said plurality of nodes comprises an optical switch;
• a plurality of links wherein:
• each link of said plurality of links comprises at least one optical fiber,
• each link of said plurality of links optically connects two nodes of said plurality of nodes,
• at least one link of said plurality of links includes an input optical fiber connected to said optical switch and transmitting a first light beam, and
• at least one link of said plurality of links includes an output optical fiber connected to said optical switch and transmitting a second light beam;
• wherein said optical switch comprises:
• a first Risley prism pair disposed in an optical path between said input optical fiber and said output optical fiber;
• and
• a second Risley prism pair disposed in said optical path between said first Risley prism pair and said output optical fiber;
• a first actuator for said first Risley prism pair, wherein said first actuator adjusts a first deflection angle of said first Risley prism pair so that said first Risley prism pair steers said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• a second actuator for said second Risley prism pair, wherein said second actuator adjusts a second deflection angle of said second Risley prism pair so that second Risley prism pair aligns said second light beam to be incident on a first outside prism face of said first Risley prism pair, thereby forming an aligned optical path between said input optical fiber and said output optical fiber wherein a signal light beam is transmitted over said aligned optical path between said input optical fiber and said output optical fiber.

An optical communication system comprising:

• a plurality of nodes;
• at least one link between two nodes in said plurality of nodes;
• a first node in said plurality of nodes, said first node comprising:
• an input optical fiber transmitting a first light beam;
• a first Risley prism pair disposed in an optical path between said input optical fiber and said at least one link;
• a first actuator for said first Risley prism pair, wherein said first actuator adjusts a first deflection angle of said first Risley prism pair;
• and
• a second node in said plurality of nodes, said second node comprising:
• an output optical fiber transmitting a second light beam;
• a second Risley prism pair disposed in said optical path between said first Risley prism pair and said output optical fiber;
• wherein said first actuator adjusts said first deflection angle so that said first Risley prism pair steers said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• a second actuator for said second Risley prism pair, wherein said second actuator adjusts a second deflection angle of said second Risley prism pair so that said second Risley prism pair aligns said second light beam to be incident on a first outside prism face of said first Risley prism pair, thereby forming an aligned optical path between said input optical fiber and said output optical fiber wherein a signal light beam is transmitted over said aligned optical path so that said first node optically communicates over said at least one link with said second node.

An actuator for a Risley prism pair, said actuator comprising:

• an optical path;
• a first drive motor connected to a first Risley prism wherein a first drive motor rotation is transmitted to a first rotation of said first Risley prism about a central axis without blocking said optical path;
• a second drive motor connected to a second Risley prism wherein a second drive motor rotation is transmitted to a second rotation of said second Risley prism about said central axis without blocking said optical path;
• said second rotation and said first rotation are independent;
• and
• an outside diameter of said actuator with respect to said central axis is less than 2.5 cm.

A method for optical beam alignment comprising steps of:

• inserting a first light beam into a first Risley prism pair;
• inserting a second light beam into a second Risley prism pair;
• adjusting said first Risley prism pair to steer said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• and
• adjusting said second Risley prism pair to deflect said second light beam to be incident on a first outside prism face of said first Risley prism pair;
• thereby forming an aligned optical path.

A method for optically switching light beams in an optical switch, comprising steps of:

• selecting an input optical fiber and an output optical fiber to be optically connected to each other;
• inserting a first light beam in said input optical fiber to be transmitted through a first Risley prism pair;
• inserting a second light beam in said output optical fiber to be transmitted through a second Risley prism pair;
• adjusting said first Risley prism pair to steer said first light beam to be incident on a second outside prism face of said second Risley prism pair;
• and
• adjusting said second Risley prism pair to align said second light beam to be incident on a first outside prism face of said first Risley prism pair;
• thereby forming an aligned optical path between said input optical fiber and said output optical fiber.