Acousto-optic frequency shifter utilizing multi-turn optical fiber

Abstract From the Canadian patent

Abstract of the Disclosure, A fiber optic frequency shifter comprises an optical fiber having an acoustic conducting medium for propagation of an acoustic signal. The acoustic medium is preferably shaped as a rod, and the acoustic signal propagates longitudinally down the rod. The optical fiber is wound around the rod with plural turns such that the axis of the fiber is at an angle relative to the wave fronts of the acoustic signal. As the acoustic signal propagates through the rod, it causes stress on the portions of the fiber in contact with the rod. The stress on the fiber caused by the acoustic wave causes optical energy to be transferred between two propagation modes of the fiber. This …