Bend resistant large mode area fiber with step-index core and single trench

摘要： A novel bend resistant large mode area ?ber with step-index core and single trench in the cladding is proposed. Numerical results demonstrate that the largest e?ective mode area reaches up to 2460 μm2 at the wavelength of 2 μm when the bend radius is only 10 cm. To achieve the better performance of single mode, the loss ratio of the lowest loss of higher order mode to the highest loss of fundamental mode can reach up to 886 with a fundamental mode bend loss lower than 0.0083 dB/m through optimizing structure parameters. The circular symmetry of ?ber structure makes it insensitive to the bending direction. Furthermore, this ?ber structure can be also used to develop bend resistant large mode area ?ber with high performance at the wavelengths of 1.06 μm and 1.55 μm. Due to large mode area, good single mode properties, small bend radius and insensitivity to bend direction, this ?ber has the potential application for compact high power ?ber lasers.