Hybrid hollow-core polarization-maintaining fiber with high birefringence and wide single mode bandwidth

A novel hybrid hollow-core polarization-maintaining fiber is proposed by combining the photonic bandgap mechanism and anti-resonant effect. High birefringence can be achieved by introducing a pair of negative curvature anti-resonant layers into the air core of a 7-cell HC-PBGF to obtain two-fold rational symmetry. Within the wavelength range from 1.45 mu m to 1.65 mu m, the birefringence reaches up to the magnitude order of 10(-3) and high-order mode suppression ratio, which is defined as the ratio of the lowest loss of high-order modes to the highest loss of fundamental modes, is greater than 100. Hence, the proposed fiber can realize high birefringence and single mode simultaneously in the 200 nm wide wavelength range. Besides, an extended structure by changing the position of the anti-resonant layers also proves the advantages of hybrid structure in achieving high birefringence and single mode operation. The proposed hybrid structure owns great potential for polarization-sensitive applications and provides a new idea to design hollow-core polarization-maintaining fibers with high birefringence and single mode.