Abstract

Seeded SHG in fibres is quantitatively explained by the proposition that the longitudinal field of the pump mode is involved in the ionisation of Ge-Si wrong bonds through a 3-photon ionisation process invoving two pump photons and one seed photon. This interference produces a grating of defects which has the correct inversion asymmetry to produce SHG. Optical pumping of the trapped electrons in Ge(l) centres developes an electrostatic field which produces SHG by the EFISH mechanism.

© 1991 Optical Society of America