Optical fiber non-reciprocal phase shifters and optical isolators using them

摘要

In accordance with the invention, an optical fiber phase shifter comprises a length of asymmetrical optical fiber disposed perpendicular to a magnetic field for providing a non-reciprocal phase shift. Preferably the fiber is wound in a circular coil and exposed to an axial field as from a pancake magnet. In an isolator, the fiber length and magnet strength are chosen to provide non-reciprocal phase shifts of +/-45 DEG or +/-90 DEG . The isolator including the phase shifter can be any of several configurations.