Fiber-optic delay lines for microwave signal processing

Glass fibers can be made with attenuation coefficients as low as 0.4 dB/µs for electromagnetic energy in the 1-µm wavelength region. It is shown that this property, together with the potentially very large bandwidths attainable, could provide for delay lines with time-bandwidth products as high as 10
⁵
. The status and limitations of optical fibers are assessed from the delay line viewpoint, and their application to matched filters indicated.