Analysis of High Birefringence of Four Types of Photonic Crystal Fiber by Combining Circular and Elliptical Air Holes in Fiber Cladding

Figure 3

The birefringence as function of wavelength of four types of PCFs, whereas the hole spacing remains constant at $\mathrm{\Lambda }$  =  1.96 μm, $A/{\mathrm{\Lambda }}^2$  =  0.4, $a_1/b_1=c_1/d_1=c_2/d_2=a_3/b_3$  =  0.75, and the ratio of large and small air holes fixed $\eta (a_1/c_1=a_2/b_2=a_3/c_3)$  =  5.5.