Numerical investigation for the mode transmission characteristics of a large mode area optical fiber with heterogeneous helical claddings designed for 2.0 µm.

ABSTRACT

Large mode area (LMA) fibers are widely used in high-power fiber lasers to solve the nonlinear problems. In this Letter, a novel LMA fiber with heterogeneous helical claddings (HHCs) is proposed. A coordinate transformation simulation technique is adopted to analyze the fiber mode transmission characteristics. The effects of the fiber parameters such as θ,Λ,r,n0,n1,n2,n3, and λ on the mode transmission characteristics include loss coefficient L and effective mode area Aeff. When θ=14∘, Λ=22mm, n0=n2=1.439, and n1=n3=1.438 are adopted. The loss coefficients are L01=0.093dB/m, L11=9.47dB/m, and L21=23.36dB/m; the single-mode fiber diameter 2r is at least 60 µm; and the corresponding effective mode field area Aeff is 2025µm2. As the helix pitch is a centimeter order of magnitude and the fiber is all solid state, the HHC fiber is relatively easy to fabricate and convenient for cutting, splicing, etc., and will be well applied in the field of high-power fiber lasers.