Nonlinear properties of superconducting point contacts and prospects for their use in quantum electronics

Results of experimental and theoretical studies of the nonlinear properties of superconducting point contacts when used in microwave and laser frequency multiplication and mixing modes are reviewed. The advantages of contacts with large critical currents for measuring submillimeter and far-infrared laser frequencies are demonstrated both theoretically and experimentally. The use of the Josephson junction in quantum electronics for building tunable oscillators in the submillimeter and far-infrared ranges and for frequency synthesis from microwaves to the visible by using a single nonlinear element is discussed.