LAUSR

Abstract We demonstrate a highly efficient, broadband fiber-optic intermodal converter. The technique relies on a long period grating mechanically induced in a two-mode fiber. A compact, portable apparatus was designed and fabricated, where period-variable metallic corrugation is implemented to form periodic micro-bends along the fiber. The coupling strength between the interacting fiber modes and the grating period can be tuned continuously and individually using two control knobs in the apparatus. Experimental results show that the complete coupling between the LP01 and LP11 modes is achieved, which is confirmed by an observed over-coupling while increasing the grating strength. For the short fiber length of