Modeling an MMF Connector via Point Radiance Matrix and its Application in Automotive SI-MMF Connection

Recently, multimode fibers and their application, such as in-vehicle systems where many in-line connectors are inserted in short-range transmissions, have garnered considerable research interest. As such applications require extremely high reliability, simulation technology that considers multimode fiber harnessing under unfavorable conditions, such as various fiber lengths and connector misalignments, has been required. Many calculation methods for modal bandwidth and connector loss have been proposed to date; however, the 3D modal power coupling equation at the connection point has not been derived due to the calculation difficulty by linking the near- and far-field patterns. Herein, we propose a ‘point radiance matrix model’ to compute the complex mode-power conversion at the step-index (SI) fiber connectors. Accordingly, we derived new equations for calculating the power distribution at the receiving fiber according to the fiber connector misalignment parameters, which can be used for link level evaluation from light source to detector. Moreover, the rules governing the power transferred from the emitting fiber to the receiving fiber were investigated under generic alignment conditions, including random combinations of longitudinal, lateral, and tilt misalignments. Applications of the proposed matrix method could contribute toward the computation of mode-power conversion at graded-index (GI) fiber connectors in case the point radiance on the emitting fiber end face is found.