Abstract

For several years, visible light generation phenomena have been observed in IR-pumped monomode fibers. Some experiments show that third- harmonic generation can be achieved when highpower pulses from a 1064-nm Nd:YAG laser are coupled into a few monomode silica-based fibers.¹ Moreover, recent observations have suggested that second-order nonlinear processes could also appear in the same type of fiber^2,3; as such effects are theoretically forbidden in isotropic media, structural anomalies of the glassy state are expected to be at the basis of such behavior.

© 1987 Optical Society of America