All-fiber acousto-optic frequency shifter

Abstract

An all-fiber-optic frequency shifter is demonstrated that uses mode coupling between the LP(01) and LP(11) modes by a traveling acoustic flexural wave guided along the optical fiber. The input and output leads of this frequency shifter are single-mode fibers. Unity mode-conversion efficiency for cw operation is achieved at 8-MHz frequency shift with about 0.25 W of electrical input power. Carrier and image sideband suppression of 15 and 35 dB, respectively, are demonstrated.