A coherent detector is able to independently demodulate these carriers.
2.
:If you build a perfect coherent detector for any one of those carriers it will not respond to any of the other carriers.
3.
A common choice is left and right circular polarizations, for example to model the different propagation of waves in two such components in circularly birefringent media ( see below ) or signal paths of coherent detectors sensitive to circular polarization.