Angular alignment of highly birefringent fibers employing acoustically scanned time-delay technique

We demonstrate a technique for accurate angular alignment of highly birefringent fibers by using a variable-delay interferometer. The variable-delay interferometer is constructed from an optical fiber supporting LP/sub 01/ and LP/sub 11/ modes. The intermodal time delay is varied by an acoustic pulse propagating along the fiber. Using a broadband optical source the time delays in two sections of highly birefringent fibers are scanned by the traveling acoustic pulse, and with the help of the interference peaks the alignment angle is adjusted. A tolerance angle of 0.09/spl deg/ corresponding to -56 dB is estimated.