Formation of relief gratings in photoreactive polymers via gas phase modification

Optically pumped DFB lasers based on conjugated polymers have been demonstrated during the past years. Optical feedback can be introduced by a spatial periodical variation of the refractive index. We investigated the W-induced formation of gratings in polymer films which act as a matrix for the active material. Irradiation of poly(4-vinylbenzyl thiocyanate) and poly(styrene-co-4-vinylbenzyl thiocyanate) caused an increase of the refractive index no by +0.03, Irradiated and unirradiated zones showed different reactivity towards gaseous modification agents (amines) which caused additional changes of the refractive index and an increase of the film thickness in the irradiated zones. The formation of gratings in such films by patterned illumination and subsequent gas phase modification is shown.