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...http://www.google.de/patents/US4735484?utm_source=gb-gplus-sharePatent US4735484 - Acousto-optic frequency shifter utilizing multi-turn optical fiber
