Analysis of Air Core Index Guided Photonic Crystal Fiber

In this paper, two types of PCF structure are designed as air core index guided with three rings of three different diameters nmis numerically investigated, using finite element method (COMSOL Multi Physics3.2a). The impact of the air-core on the three parameters that is, effective mode index, confinement loss and birefringence behavior are studied for this two different types of structure. By destroying the symmetry of the structure and make effective index difference between two orthogonal polarization states, birefringence is achieved. By using different diameter of air- holes around the newly formed core, the confinement loss is reduced and birefringence becomes high. It is seen that the effective mode index decreases with increase in wavelength and birefringence decreases with increase in normalized frequency.