Fiber-optic frequency shifter using a grating acoustic scanner.
A fiber-optic single-sideband frequency shifter using a grating acoustic scanner has been demonstrated. By using the surface-wave-to-bulk-wave conversion mechanism of a LiNbO(3) scanner, a traveling acoustic bulk wave with a frequency of approximately 42 MHz was generated and was incident at an angle upon an optical fiber. This angle is adjustable by changing the surface-wave frequency to produce phase-matched coupling between two polarization modes or two spatial modes of light in the fiber. An optical coupling efficiency of approximately 70% and carrier and image sideband suppression of 18 and 35 dB, respectively, were realized.
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