A multitude of output frequencies can be obtained using the indirect approach by heterodyning
the outputs of two or more oscillators.
The coherent optical monolithic phased array steering system (COMPASS), shown in Figure 3, is based on optical heterodyning employed to produce microwave phase shifting.
In COMPASS, RF signals are produced by the heterodyning together two lightwaves that must be generated with a difference frequency equal to the desired RF output frequency.
Equation 1 demonstrates three important properties for the use of optical heterodyning in RF phase control.
A multitude of output frequencies can be obtained in the indirect approach by heterodyning
or mixing the outputs of two or more oscillators.
, a method of achieving RF/microwave phase shift using optical processing, has long been known.
Many of the upper atmospheric molecules, including chemical radicals responsible for ozone destruction, have spectral lines that can be measured with this technique using heterodyning
to attain 700 GHz operation.
A multitude of output frequencies are obtainable in the indirect approach through the heterodyning
or mixing of the outputs of two or more oscillators.