Experimental and analytical investigation of LP_(01)-LP_(11) mode interference

摘要

We introduce an analytical theory of LP01-LP11 mode interference and investigate its application in curvature measurement. Under the weakly guiding condition, an analytical formulation for predicting dip wavelength in the transmission spectrum is proposed. The applicability of the proposed formulation is further explored in terms of curvature measurement based on a few-mode multi-core fiber (FM-MCF). The mechanism of curvature response is analytically presented and verified through numerical simulation and experiments. The comparison of analytical and numerical results is found to be in good agreement when curvature varies from 0 to 1.8m(-1). Meanwhile, a good agreement between the experimental and theoretical values of dip wavelength shift is also observed. Moreover, we find that the temperature effect can be eliminated by using two cores of the FM-MCF during curvature measurement. Through experimental tests, the curvature values are accurately predicted under varying temperatures with maximum error controlled within 6.6%.