Abstract: The present invention relates to the. use of optimized magnet design, magnetic circuit design and wire coil design to improve latching reliability and reduce driving current for the switchable Faraday rotator devices. The geometrical parameters of semi-hard magnet are optimized to produce maximal magnetic field at the location of magneto-optic crystal and hence improve latching reliability and reduce driving current. The wire coil is optimized in coil length, wire gauge, and number of turns to produce most efficient energy transfer and hence reduce driving current and driving voltage. To reduce magnetic energy loss, soft magnetic material is included to form a magnetic conductive close loop and further reduces driving current requirements.

Abstract: Randomly polarized light impinges upon a birefringent crystal, is split into orthogonal polarization components and emerges from the crystal separated by a walk-off distance. The light beams then impinge on polarization rotators that cause a rotation of the plane of polarization by +45° and −45°. The light then encounters a variable polarization rotator in which the plane of polarization is rotated through a angle that varies in response to an externally-applied control signal. The maximum operating range (0 to 100% attenuation) is achieved when the variable rotator is capable of rotations in the range ±45°. A second birefringent crystal functions as a beam displacer. The beams encounter two wave plates configured to produce rotation angles of 0° and 90° followed by a retroreflector. The reverse traverse of the attenuator causes the light to emerge at an output port attenuated in intensity.

Abstract: The present invention relates to the use of magnetic materials in combination with magneto-optic materials to improve performance of Faraday rotator devices by enhancing the latching capability and reducing the driving current. Semi-hard magnetic materials are advantageously used in connection with some embodiments of the present invention. Placing such semi-hard magnetic materials in proximity with the magneto-optic material enhances latching and reduces the drive current required to cause switching. Encompassing both the magneto-optic material and the semi-hard magnetic material further reduces drive current requirements and enhances latching by reducing leakage of the magnetic field from its generation within the coil to the magneto-optic material. Some embodiments further include soft or semi-hard material encompassing the coil.