Optical downconverter

Optical DownConverter (ODC) is an example of a non-linear optical process, in which two beams of light of different frequencies formula_1 and formula_2 interact, creating microwave with frequency formula_3. It is a generalization of microwave. In the latter, formula_4, both of which can be provided by a single light source. From a quantum mechanical perspective, ODC can be seen as result of differencing two photons to produce a microwave. Since the energy of a photon is given by
formula_5
the frequency summing formula_3 is simply a statement that energy is conserved.
In a common ODC application, light from a tunable infrared laser is combined with light from a fixed frequency visible laser to produce a microwave created by a wave mixing process.
The ODC use milimeteric microwave cavity that include photonic crystal that provide by two signal frequency light source. The microwave is detected by the cavity antenna.