A fiber-optic frequency shifter utilizing a traveling torsional acoustic wave to couple the polarization eigenmodes of a highly linearly birefringent optical fiber is demonstrated. The frequency-shifter configuration is such that the acoustic-wave generator and optical fiber are coaxial. The device is thus more rugged than previous free-fiber frequency shifters, which have incorporated a T junction between the acoustic generator and optical fiber. The optical frequency shift was 3.204 MHz, and an optical coupling efficiency of 12% was obtained with 4 W of electrical drive power applied to the acoustic transducer.
© 1992 Optical Society of America
Original Manuscript: October 28, 1991
Published: February 15, 1992
M. Berwick and D. A. Jackson, "Coaxial optical-fiber frequency shifter," Opt. Lett. 17, 270-272 (1992)