title: Optical downconverter
text: # Optical downconverter
  
  Optical DownConverter (ODC) is an example of a non-linear optical process, in which two beams of light of different frequencies $\omega _{1}$ and $\omega _{2}$ interact, creating microwave with frequency $\omega _{3}=\omega _{1}-\omega _{2}$. It is a generalization of microwave. In the latter, $\omega _{1}=\omega _{2}$, 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
  
  $E_{\nu }=\hbar \omega ,$
  
  the frequency summing $\omega _{3}=\omega _{1}-\omega _{2}$ 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.
  
  