Abstract

Recent research has dealt with phenomena where coherent generation of electromagnetic (em) waves is intimately involved with multiphoton excitation, leading to results that cannot be explained by considering coherent generation and multiphoton excitation as separate phenomena. In particular, the disappearance with increasing vapor pressure¹ and the reappearance with retroreflection² of a multiphoton ionization signal, as well as the disappearance with increasing pressure of fluorescence from a multiphoton excited state,³ have been explained by considering the effect of coherent third-harmonic generation on the multiphoton excitation.^4,5 These explanations present specific calculations showing that the total excitation is reduced by the harmonic-generation process, but they fail to address the underlying general principle that leads to such a reduction.

© 1984 Optical Society of America