Method and apparatus for controlling an optical signal

A birefringence device that comprises:

• a first birefringence element that is operational to receive a first optical signal and control the phase of the first optical signal based on a first control input;
• a second birefringence element that is operational to receive a second optical signal and control the phase of the second optical signal based on a second control input;
• and
• an optical path that connects the first birefringence element to the second birefringence element.

A method for controlling an optical signal that comprises:

• receiving an optical signal into an optical coupler;
• splitting the optical signal into at least a first portion and a second portion and providing the first portion of the optical signal to a first optical path and providing the second portion of the optical signal to a second optical path;
• transporting the first portion of the optical signal to a birefringence element over the first optical path and transporting the second portion of the optical signal to the birefringence element over the second optical path;
• applying a phase offset to the portions of the optical signal in the birefringence element based on a control input and then providing the first portion of the optical signal to the second optical path and providing the second portion of the optical signal to the first optical path;
• in the optical coupler, receiving the first portion of the optical signal from the second optical path after it has passed through the birefringence element and receiving the second portion of the optical signal from the first optical path after it has passed through the birefringence element;
• and
• in the optical coupler, routing the optical signal based on the phase offset applied by the birefringence element.

An optical device for controlling an optical signal that comprises:

• an optical coupler;
• a birefringence element that is operational to control the optical signal based on a control input;
• a first optical path that connects the optical coupler to the birefringence element;
• and
• a second optical path that connects the optical coupler to the birefringence element wherein a loop is formed comprised of the optical coupler, the first optical path, the birefringence element, and the second optical path;
• wherein the birefringence element is comprised of two unidirectional birefringence modulators.

An optical device for controlling an optical signal that comprises:

• an optical coupler;
• a birefringence element that is operational to control the optical signal based on a control input;
• a first optical path that connects the optical coupler to the birefringence element;
• and
• a second optical path that connects the optical coupler to the birefringence element wherein a loop is formed comprised of the optical coupler, the first optical path, the birefringence element, and the second optical path;
• wherein the control signal is a microwave signal.

An optical device for controlling an optical signal that comprises:

• an optical coupler;
• a birefringence element that is operational to control the optical signal based on a control input;
• a first optical path that connects the optical coupler to the birefringence element;
• a second optical path that connects the optical coupler to the birefringence element wherein a loop is formed comprised of the optical coupler, the first optical path, the birefringence element, and the second optical path;
• and
• an optical circulator connected to the optical coupler,
• the control signal is a microwave signal.