Large mode area single mode photonic crystal fiber with ultra-low bending loss

A novel asymmetrical structure of Photonic Crystal Fibers (PCFs) has been proposed in this article. The first ring consists of three big air holes which can confine the propagating mode in the core region. The second ring consists of twelve doped rods with two different diameters which can decrease the difference of refractive index between the core and the cladding in order to provide the large mode area. The third ring consists of eleven air holes to help the higher-order-modes (HOMs) to leak out. The bending properties of proposed fiber are investigated by full vector finite element method with an anisotropic perfectly matched layer. The numerical results show that the effective mode area of the FM of the proposed fiber is as large as 595.02 μm2 with small bending radius of 10 cm at the wavelength of 1064nm. The bending loss of fundamental mode (FM) is 9.884×10−5dB/m, while large bending loss for the high-order mode (HOMs) is 14.685dB/m. Moreover, the loss ratio can reach 1.45×105which can realize the effective and stability single-mode operation. Therefore, the novel fiber has potential application in high-power fiber lasers.