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A fiber Bragg grating is inscribed in a two-mode fiber using a 193-nm excimer laser and a phase mask. Strong LP01and LP11mutual coupling as large as -22.5 dB, which corresponds to a modal conversion efficiency of more than 99%, is experimentally achieved. The intermodal coupling mechanism is theoretically analyzed through a finite element method. This device can be used as a low-cost reflective LP01↔ LP11converter.
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Wu et al. (2012) studied this question.
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