| 摘 要： | We report here an ultra-broadband linearly polarized(LP) LP_(01)-LP_(11) mode converter operating at 1 μm based on a long period fiber grating(LPFG) fabricated in a conventional two-mode fiber(TMF) by a line-focused CO_2 laser. The measured 3d B bandwidth is about 240 nm, which is the broadest bandwidth for such fiber mode converters. The maximum conversion efficiency between the LP_(01) and LP_(11) modes is 99% over the range of 1000 nm to 1085 nm, almost covering the whole emission band of Yb~(3+), which is useful for further power scaling of high-power fiber lasers operating at the 1 μm band.
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