) ▁E rec . ▁In ▁sil ica ▁glass , ▁the ▁non - linear ▁coefficient ▁induced ▁is ▁~ 1   pm / V , ▁while ▁in ▁fib ers ▁it ▁is ▁a ▁fraction ▁of ▁this ▁value . ▁The ▁use ▁of ▁fib ers ▁with ▁internal ▁electro des ▁makes ▁it ▁possible ▁to ▁pole ▁the ▁fib ers ▁to ▁make ▁them ▁exhib it ▁the ▁linear ▁electro - opt ic ▁effect ▁and ▁then ▁control ▁the ▁ref ract ive ▁index ▁with ▁the ▁application ▁of ▁voltage , ▁for ▁switching ▁and ▁mod ulation . ▁The ▁recorded ▁field ▁in ▁a ▁po led ▁fi ber ▁can ▁be ▁er ased ▁by ▁expos ing ▁the ▁po led ▁fi ber ▁from ▁the ▁side ▁to ▁U V ▁radiation . ▁ ▁This ▁makes ▁it ▁possible ▁to ▁artificial ly ▁create ▁an ▁electric - field ▁gr ating ▁with ▁arbitrary ▁period , ▁which ▁satisfies ▁the ▁condition ▁necessary ▁for ▁quasi - phase - match ing . ▁Period ic ▁pol ing ▁is ▁used ▁for ▁efficient ▁frequency - d ou bling ▁in ▁optical ▁fib ers . ▁ ▁References ▁ ▁Category : G lass ▁Category : Non linear ▁opt ics <0x0A> </s> ▁Dor is ▁Che p kw em oi ▁Change y wo ▁( born ▁ 1 2 ▁December ▁ 1 9 8 4 ▁in ▁Che by uk , ▁Mount ▁El gon ▁District ) ▁is ▁a ▁Ken yan ▁long - distance ▁runner ▁who ▁special ises ▁in ▁the ▁ 1 0 , 0 0 0 ▁metres ▁and ▁cross ▁country ▁running . ▁ ▁She ▁began ▁to ▁enjoy ▁success ▁in ▁athlet ics ▁in ▁ 2 0 0 6 , ▁becoming ▁the