Pixelation-free light pattern generation through multi-core fibers using digital optical technologies

Multi-core fibers (MCF) are commonly used for endoscopic imaging, e.g. in biomedicine. Usually a coherent fiber bundle with several ten thousand cores is employed together with a lens system on its distal end. However, pixelation effects are occurring and the miniaturization is strongly limited. To circumvent these limitations, a spatial light modulator (SLM) is employed on the proximal side of a single-mode MCF. It is possible to capture 3D-objects or to create random wavefronts at the distal fiber end, e.g. for adaptive light spot generation without pixelation effects in biomedicine. Since MCFs show phase distortion between individual cores (e.g. coupling between cores, speckle effect), it is necessary to correct these distortions in order to perform the above-mentioned tasks. Therefore, digital optical phase conjugation (DOPC) is applied by using digital holography to measure the distortions and the SLM to correct them.