Fiber-optic tunable microwave transversal filter

A fiber-optic finite impulse response filter with continuously tunable unit time delays is developed and studied. The filter consists of eight taps with progressively longer segments of high-dispersion fiber, but completed with dispersion-shifted fiber to nominally identical overall lengths. The time delays through each tap are tuned by varying the wavelength of the optical carrier. The constructed 8-tap filter exhibits bandpass characteristics with a Q of 30. The bandpass band is continuously tuned over a full octave from under 9 GHz to over 18 GHz with a single low-voltage control signal that demonstrates the technique's applicability to adaptive systems.< >