EFFICIENT FORMATION OF A CHI((2)) GRATING IN A GERMANOSILICATE FIBER CONTAINING NITROGEN

A chi((2)) grating, capable of converting light to the second harmonic with an efficiency of 2%, was formed for the first time in a germanos ilicate optical fibre doped with nitrogen and prepared by the method o f surface plasma-chemical vapour deposition. A comparison was made of the properties of this grating with those of chi((2)) gratings formed in a germanosilicate fibre free of nitrogen. The high efficiency of th e conversion processes, observed when a chi((2)) grating was formed in a nitrogen-doped fibre, indicated the existence of fast-relaxing phot ocentres associated with nitrogen and accelerating growth of a chi((2) ) grating in the presence of phase fluctuations of laser radiation.