Low-cost high-speed multichannel fiber-optic correlator

It is shown that, for stationary signals, by use of a microwave switchable delay line the number of channels in a multichannel fiber-optic correlator may be simply expanded. By replacing one optical tree with an electrical tree and by performing the AND operation with double-gate metal-oxide semiconductor field-effect transistors, we demonstrate two methods of reducing the cost of a multichannel architecture without a reduction in speed. Using optical implementation for delays longer than 5 ns and microwave implementation for delays shorter than 5 ns, we obtain 20 points of the correlation function of a 500-MHz signal.