Wavelength Tunable Filter Based on Acousto-Optic Modulation of a Double-Core Fiber

A tunable notch filter is acoustically modulated in the transmission spectrum of a double-core optical fiber. Flexural acoustic waves dynamically change the coupling power and the wavelength of the propagating modes, allowing to switch and tune wavelengths between the two cores. A maximum modulation depth of 5.4 dB and a tuning wavelength range of 8.4 nm are achieved with the present configuration. The results indicate new possibilities for application in space division multiplexing systems, dynamic couplers, gain equalizers, and fibers lasers.