The pa per pres ents a brief over view of con tem po rary ELION tech niques with stress on their use for ma te rial mod i fi ca tion and do sim e try. In the at tempt to avoid some com mon mis judges of ir ra di a tion ef fects, spe cial at ten tion is paid to ex act def i ni tion of ir ra di a tion ge om e try and care ful ad just ment of dose rates, which en able a proper elab o ra tion of ex per i men tal re sults. In par tic u lar, ef fects of grays ir ra di a tion on prop er ties of com mer cial op ti cal fibres, split ters, con nec tors, and fi bre joints are ex am ined, which en ables mon i tor ing of ir ra di a tion ef fects in com plex con fig u ra tions made of ma te ri als with dif fer ent ra di a tion hard ness (re sis tance). It has been es tab lished that grays ir ra di a tion of the in ves ti gated el e ments in flu ences, in dif ferent ways, the trans mis sion of la ser beam sig nals of var i ous wave lengths, un der dif fer ent modu la tion re gimes. Af ter ir ra di a tion, the sig nal at ten u a tion is no tice ably larger, both in op ti cal con nec tors and op ti cal split ter, than be fore it, and the ef fect in creases in time. The ef fects are more pro nounced at the 99 % than at the 1 % Y-split ter out put at both mea sured wave lengths, and are more pro nounced at 1310 nm than at 1550 nm.