We have been Interested in multiphoton transitions across various types of barrier in both single-layer and multilayer metal–barrier–metal junction structures. The polarization characteristics of such transitions can be highly nonlinear, and the consequent muitiphoton parametric processes can be used to investigate such structures. We have specifically examined the five-photon tunneling transition in which three quanta of 357.5157-cm−1 photons from a water vapor laser are mixed with a 1071.88374-cm−1 photon from a CO2 laser. Particular attention has been paid to input coupling of the incident photons and the output coupling of the microwave signal at 20 GHz.
© 1984 Optical Society of AmericaPDF Article