Text Box: ---------------------------------------------------------------- All of quantum mechanics is contained in the two-slit experiment; unfortunately, no one understands the two-slit experiment – Feynman ----------------------------------------------------------------
Text Box: Richard Feynman's elaboration of the two-slit experiment* is a classic discussion of wave-particle duality and the uncertainty principle. ... *Feynman, R. P., Leighton, R. B. & Sands, M. L. The Feynman Lectures on Physics Vol. 3, 1-4 (Addison-Wesley, Reading, 1965) Illuminating Entanglement, Tony Sudbery (Department of Mathematics, University of York, UK), Nature 379, 403-404 (1 February 1996)
Text Box: Frequency mixing. In three-wave sum- and difference-frequency mixing, two incident waves at n1 and n2 are converted to a third wave at n3 according to [n3 = n1 ± n2]. The simplest interaction of this type is second-harmonic generation in which n3 = 2n1. ... By using radiation from pulsed lasers, conversion efficiencies of over 90% have been achieved in second-harmonic generation. With continuous-wave lasers, it is more efficient if the nonlinear crystal is placed in the laser cavity. Conversion efficiencies of over 30% of the internal laser power have been obtained in this way for continuous-wave lasers. Second-harmonic generation and second-order frequency mixing have been demonstrated at wavelengths ranging from the infrared to the ultraviolet, generally coinciding with the transparency range of the nonlinear crystals. McGraw-Hill Encyclopedia of Physics, Second Edition (1993); pp 851-852