Structural design and properties study of rectangular lattice high polarization low-loss-Bi-Ge-Ga photonic crystal fiber

Asymmetric structure photonic crystal fibers are widely used. Its good polarization characteristics, flexible dispersion control ability and low limit loss quality play a key role in regulating and improving the performance of polarization fiber devices, nonlinear optical fibers, optical communication fibers, and fiber sensors. In this paper, high refractive index bismuth-germanium-gallium laser glass material is used and a photonic crystal fiber with an octagonal array and a rectangular lattice arrangement structure is designed. The core defect area cladding and outer cladding are all circular air holes. The simulation experiment data show that when the structural parameter M=0.5 and 0.6, the birefringence coefficients at the wavelength of 1.55 μm are 1.16×10⁻² and 1.33×10⁻², respectively; In the short-wave region of the near-infrared band, the dispersion range of rectangular lattice photonic crystal fiber is ±30 ps·nm⁻¹·km⁻¹ and −18−32 ps·nm⁻¹·km⁻¹, respectively. The dispersion slope is low. The dispersion curve has a zero dispersion point, which demonstrates good continuous spectrum control ability; When M=0.5, 0.6, in the band of 1.00−1.90 μm, the limit loss keeps in 10⁻⁷−10⁻⁹ dB·km⁻¹ stably; At the wavelength of 1.55 μm, the limit loss are 2.32×10⁻⁷ and 1.62×10⁻⁸ dB·km⁻¹, respectively.