Erasable and rewritable fiber bragg grating (FBG) in dye-doped photonic liquid crystal fiber (PLCF).

Abstract

This project demonstrates photoinduced fiber bragg grating(FBG) in a dye-doped photonic

liquid crystal fiber(PLCF). The occupancies of high refractive index liquid crystals hosted in the fiber are able to alter the guiding properties of PCF to change from an index guiding fiber to a photonic bandgap guiding fiber. In this report, 3 feasible modulation in refractive indices correlated to light-induced isomerization is studied, which includes trans-cis isomerization,

photo-induced orientation and photo-chemical phase transition of azopolymer. The second

part of this experiment explains the erasable and rewritable effect of FBG that is mainly caused of the polarization dependence properties of LC. By adjusting the angle of polarizer,LC inside PLCF tilts to angle perpendicular to polarizer which induces the erasable and rewritable FBG effect. In overall, the results from this experiment show that transmission bandgap shift appears at around 1090nm and transmission would decrease during the

formation of grating whereas transmission increases when the grating is erased.