The output signal of a birefringent fiber gyroscope is analyzed, and sources of error due to polarization cross coupling in the fiber and fiber components are identified. Techniques to suppress such errors by modulating the fiber birefringence and balancing the optical power in the two polarization modes are proposed and demonstrated.

A nondestructive technique for the accurate alignment of the birefringent axes of high-birefringence optical fibers at an arbitrary position is demonstrated by using an elasto-optic effect. Alignment accuracy of less than 0.5° is achieved, and the slow and fast birefringent axes can be easily distinguished. A high-birefringence-fiber directional coupler with less than -28 dB polarization cross coupling, constructed by using this technique, is described.

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A temperature- and strain-compensated two-mode fiber-optic bending sensor is presented. This sensor has the unique ability to measure bending over complex and arbitrary paths, using a strictly passive sensing tether. Experimental evidence demonstrates the properties of the sensor and the effectiveness of the compensation technique.

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