Effect of Soft Glass Rod Infiltration in the Core of Photonic Crystal Fiber

The effect of core infiltration in the optical properties of Photonic Crystal Fiber (PCF) is investigated. The soft glass rod infiltration provides greater refractive index contrast between the core and the cladding. This modification improves the optical properties significantly. Four structures of photonic crystal fiber (Hexagonal, Octagonal, Decagonal and Elliptical) are investigated and a comparative study has been made to observe the difference in the optical properties due to the infiltration. It is observed that, by introducing this infiltration the birefringence is improved up to the order of $10^{-1}$ and a very high negative dispersion coefficient of 7744ps/(km.nm) can be achieved. The birefringence is increased $4.82\times10^{6}$ times in the hexagonal PCF, $5.38\times10^{5}$ times in octagonal PCF, 546 times in decagonal PCF and about 8 times in the elliptical PCF at operating wavelength due to the core infiltration. The positive dispersion of the fiber is eliminated and a very high negative dispersion co-efficient of 7744ps/(km.nm) is achieved in hexagonal PCF, a relatively flattened dispersion is obtained in other cases due to infiltration at operating wavelength. The nonlinearity is increased about 73 times in case of hexagonal PCF and in other cases it is increased about 2 times. The confinement loss is reduced up to the order of $10^{-11}$ due to the infiltration at the operating wavelength of 1550 nm. Another comparative study shows that the introduced fibers outperform most of the recent works with a more simple structure, which reduce fabrication complexity. The numerical investigation of the structures is conducted using full vector finite element method.