The phase-matching condition required for efficient acousto-optic polarization coupling limits the operation of some types of fiber-optic frequency shifters to relatively low frequencies (1–2 MHz). Collinear phase matching can occur at higher frequencies if the acoustically induced coupling is made spatially periodic. Using this technique, a frequency shifter operating at 5.6 MHz (2.8 times the usual collinear phase-matching frequency) has been demonstrated. A maximum coupling efficiency of 26% was achieved using 32 W of electrical input power. A 3-dB modulation bandwidth of 110 kHz resulted for the design described here. Unwanted spectral components were suppressed by 24 dB.
© 1986 Optical Society of America
Original Manuscript: January 30, 1986
Manuscript Accepted: February 26, 1986
Published: May 1, 1986
W. P. Risk and G. S. Kino, "Acousto-optic fiber-optic frequency shifter using periodic contact with a copropagating surface acoustic wave," Opt. Lett. 11, 336-338 (1986)