Effects of ultraviolet and thermal pretreatment on the formation of self-written x⁽²⁾ gratings and optical damage

In this article we report the effects of thermal and ultraviolet light pretreatments of a variety of optical fibers with different core dopants. Except for fibers codoped with phosphorus, a negative correlation was found between the onset of optical damage to the fibers and the formation of seeded second-harmonic generation (SHG). From our results and from those of other workers, we conclude that there is a link between susceptibility to optical damage and the formation of seeded SHG in germanosilicate optical fibers.