Acoustooptic modulators for single-mode fibers

The design of in-line acoustooptic modulators for single-mode fibers is discussed. The basic configuration consists of a cylindrically symmetric piezoelectric transducer fabricated on the fiber surface, so that the fiber itself acts as a cylindrical acoustic resonator. Depending on the fiber design, the acoustic wave can induce phase, birefringence, or polarization modulation of the light in the fiber. Pairs of the polarization modulators in series can be used to shift the optical frequency. Factors affecting the performance of all of these devices are discussed.