Abstract: A fiber optic interferometer provides Kerr effect compensation by intensity modulating counterpropagating waves of unequal intensity such that the average value of the square of the intensity is equal to a constant times the average value of the intensity squared, the constant preferably being equal to about two. The intensity modulation may be achieved by using a modulator in combination with a light source or by using a source in which plural frequencies combine to provide the modulation.

Abstract: A single, continuous strand of fiber optic material is wrapped about a mandrel to form oval-shaped loops having parallel sides and curved ends. A magnet is positioned so that its B-field is substantially parallel to the straight portions of the loops. As light propagates through these straight portions of the loops, its direction of polarization is rotated in accordance with the Faraday effect. The curved portions are formed to create sufficient linear birefrigence to provide a phase difference of 180 degrees between light in the two orthogonal polarization modes of the fiber. This advantageously causes the Faraday rotations in each of the straight portions to add, rather than cancel. The magneto-optic rotator of the present invention is useful in a variety of applications such as an optical isolator, a modulator, and a magnetometer.

Abstract: A fiber optic rotation sensor, employing the Sagnac effect comprising all fiber optic components positioned along a continuous, uninterrupted strand of fiber optic material. The rotation sensor includes a detection system utilizing a modulator or modulators for phase modulating at first and second harmonic frequencies light waves which counter-propagate through a loop formed in the fiber optic strand. Each modulator is operated at a specific frequency to eliminate amplitude modulation in the detected optical output signal.A phase sensitive detector generates a feedback error signal proportional to the magnitude of the first harmonic in the output optical signal. The feedback error signal controls a modulator which controls the amplitude of the second harmonic driving signal for the second harmonic phase modulator such that the first harmonic component in the output signal from the rotation sensor is cancelled or held within a small range of amplitudes.

Abstract: A fiber optic rotation sensor, employing the Sagnac effect, comprises all fiber optic components, positioned along a continuous, uninterrupted strand of fiber optic material. The rotation sensor includes a detection system utilizing a modulator for phase modulating light waves which counterpropagate through a loop formed in the fiber optic strand. The modulator is operated at a specific frequency to eliminate amplitude modulation in the detected optical output signal. The rotation sensor is mounted in a .mu.-metal housing to shield it from the effects of ambient magnetic fields. An isolator is utilized to prevent the optical output signal from returning to the laser source. This advantageously reduces power losses in the system by eliminating the need for a coupler to couple the output signal to a detector.

Abstract: A single, continuous strand of fiber optic material is wrapped about a mandrel to form oval-shaped loops having parallel sides and curved ends. A magnet is positioned so that its B-field is substantially parallel to the straight portions of the loops. As light propagates through these straight portions of the loops, its direction of polarization is rotated in accordance with the Faraday effect. The curved portions are formed to create sufficient linear birefringence to provide a phase difference of 180 degrees between light in the two orthogonal polarization modes of the fiber. This advantageously causes the Faraday rotations in each of the straight portions to add, rather than cancel. The magneto-optic rotator of the present invention is useful in a variety of applications such as an optical isolator, a modulator, and a magnetometer.

Abstract: Rotation sensor having a loop of fiber optic material in which counter propagating waves are generated with a phase relationship corresponding to the rate at which the loop is rotated. All fiber optic components are employed in the system for directing the light to and from the loop and establishing, maintaining and controlling proper polarization of the light. In one particularly preferred embodiment, the loop and other components are formed on a single strand of fiber optic material which extends continuously through the system.

Abstract: Fiber optic device for controlling the state of polarization of light. In one embodiment, a strand of fiber optic material is bent into a generally planar coil of relatively tight radius to stress the material and form a birefringent medium having principal axes which are rotated to control the polarization of light passing through the strand. In a second embodiment, one portion of a fiber optic strand is twisted about its axis to change the polarization, and a second portion of the strand is formed into a coil which is free to change in radius without additional twisting as the first portion is twisted.