Three-dimensional vector diagrams as an aid in analyzing optical devices and systems.

The usefulness of three-dimensional vector diagrams in analyzing optical systems is described. The diagrams involved are three-dimensional plots of the positive frequency spectrum of the signal. By using two diagrams to represent a given signal, one for each of two orthogonal linearly polarized components, information on signal polarization is also conveyed. Devices or systems are analyzed by noting how the diagrams of the input signal are successively altered by passage of the signal through the system. The techniques described are most useful with systems containing birefringent and dichroic elements, and with signals containing one or a few discrete spectral components. The diagrams can be used to determine both the output (optical) signal and the (rf) signal resulting from its detection by a square-law photodevice. Examples considered include two types of amplitude modulator, a single-sideband modulator, and a balanced optical detection system.