Abstract: An image rejecting microwave photonic downconverter uses a microwave sub-carrier modulation technique without concern for image frequency interference in the shifted signal, thereby allowing telecommunications systems to downconvert densely multiplexed communications channels into a low frequency band where conventionqal electronics can perform signal-processing functions. The image rejecting microwave photonic downconveter incoming microwave signals can be processed without ambiguity in direction finding applications, allowing remotable, multioctave microwave signal processing for frequency and phase determination.

Abstract: The wideband single-sideband modulator generates single-sideband (SSB) modulation with suppressed carrier utilizing traveling-wave LiNbO3 modulators in a Sagnac loop. In the wideband single-sideband modulator, optical light from a linearly-polarized source is injected into polarization-maintaining fiber (PolMF) where it is split equally via a polarization-maintaining (PolM) directional fiber coupler, resulting in counterpropagating lightwaves in a Sagnac loop. These counterpropagating waves are &pgr;/2 out of phase due to the action of the coupler and remain so when they return to the coupler because they travel equal distances around the loop. Because the coupler is a reciprocal device, if the waves return to the coupler with equal amplitudes, they will recombine and exit the original port toward the polarized light source.