Fiber Fuse Propagation Characteristics of LP01 and LP11 Modes in Few-Mode Fiber

We observe fiber fuse propagation in the LP₁₁ mode in few-mode fiber by selective propagation mode launching via a PLC-based mode multiplexer. We focus on two fiber fuse propagation parameters, namely, the propagation power threshold P_th, and the diameter of the melted area D_melted. We confirm experimentally that P_th in the LP₁₁ mode was higher than that in the LP₀₁ mode. P_th of the LP₀₁ and LP₁₁ modes increases linearly with the Gaussian beam width, which is similar to the dependence of the mode field diameter of P_th in the LP₀₁ mode. We also find a specific relationship between the power density and D_melted normalized by the Gaussian beam width regardless of input mode conditions and fiber type. Therefore, we believe that we can utilize the Gaussian beam width of the near field pattern of the LP₀₁ and LP₁₁ modes for predicting the characteristics of fiber fuse propagation in both modes.