Plastic rods with gradient refractive index were successfully fabricated by the interfacial-gel polymerization technique

in which two kinds of dopants were used for their higher refractive index and different molecular volume.The effects of dopant concentration

the molecular volume and the temperature of polymerization on the refractive index profile of the preform rods were investigated in detail.Experimental results showed that the difference of the refractive index between the center and the periphery of the preform rod increased with increasing temperature due to the increase of the gel effect and polymerization rate at a higher temperature.The parabolic refractive index ditribution was slightly flatted at lower temperature mainly due to decreasing rate of polymerization

therefore there is more time for the dopants to diffuse into the gel.