A novel noninvasive acousto-optic device for polarization coupling and frequency
shifting in optical fiber based on bulk-shear acoustic waves is reported. By use
of a coupled-mode theory, an expression is obtained to predict the amplitude
coupling efficiency. An elliptical-core-fiber polarization modulator is
demonstrated at a center acoustic frequency of 75 MHz. An amplitude coupling
efficiency of 14.3% and a 3-dB bandwidth of 3.6 MHz were observed,
comparing well with the predicted results and also comparing favorably with
similar devices based on longitudinal strain waves.
© 1993 Optical Society of America
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