Design and analysis for large-mode-area photonic crystal fiber with negative-curvature air ring

•A novel large-mode-area fiber based on negative curvature air ring is proposed.•The results show that under the condition of a five-layer six-lobed air ring with negative curvature, the mode field area reaches 1358.9 μm2.•The proposed fiber has the same performance from 1 micron to 1.8 microns wavelength band and the manufacturing tolerance is feasible.•The proposed fiber can overcome the bending radius of more than 15 cm and the bending direction has no impact on fiber performance. A large mode area photonic crystal fiber (LMA-PCF) under standard fiber size is proposed in this paper. In order to realize large mode field and low bending loss, multilayer negative curvature air ring structure is designed. The finite element method with perfectly matched layer boundaries is used to analyze the performance of PCF. The influence of various parameters of fiber structure on fiber performance is analyzed. Numerical results show that the structure can achieve large mode area with lower bending loss and smaller bending radius in the wavelength range of 1–1.8 µm. Under the condition of a five-layer six-lobed air ring with negative curvature, the mode field area reaches 1358.9 μm2. At the same time, the high-to-fundamental mode loss ratio reaches 331.5. When the bending radius is 15 cm, the bending loss of the fundamental mode is 0.21 dB/m. Within the 360° bending direction, LMA can be realized in all directions and has effective single-mode operation.