Concentric circular stress region-assisted pseudo-elliptical-ring-core polarization-maintaining few-mode fiber.

In this paper, a pseudo-elliptical-ring-core polarization-maintaining few-mode fiber structure assisted by concentric circular stress-applying region is proposed. Numerical simulation results show that the structure can stably support 14 transmission modes. By introducing two elliptical stress regions with low refractive index inside the core, and a circular stress region with concentric core between the fiber core and cladding, the effective refractive index difference between higher-order modes is significantly improved. In the C + L band, the minimum refractive index difference between adjacent modes is not less than 2 × 10−4. At 1550 nm, the effective refractive index difference between the two fundamental modes reaches 4.8 × 10−4. The mode dispersions are less than |-33| ps/nm/km, and the maximum bending loss is in the order of 10−7 dB/m (bending radius ≥2.5 cm). This work may pave the way for the development of short-distance large-capacity optical fibers. • The min Δ n eff between adjacent modes is not limited by the separation degree of the two fundamental modes. • The Δ n eff between two fundamental modes reaches 4.8 × 10−4 at 1550 nm. • Concentric circular stress region equalizes the separation degree of the lower and higher order degenerate modes. • In the whole C + L band, the Δ n eff between each guided mode is not less than 2 × 10−4. [ABSTRACT FROM AUTHOR]