Wide-field single-pixel complex-field microscopy through a multimode fiber

Single-pixel imaging (SPI) offers an elegant solution for wide-field reconstruction using only a single-point detector, showing potential from autonomous navigation to biomedical sensing. Yet, its performance collapses in highly scattering environments, where pre-defined illumination patterns become rapidly corrupted—especially critical in deep-tissue imaging. Here, we present a powerful new paradigm that integrates SPI with a thin multimode fiber (MMF) to achieve minimally invasive, coherent imaging through pure intensity measurements, called MMF-based single-pixel complex microscopy (MMF-SPCM). Without requiring any transmission matrix calibration, our method decodes wide-field complex-field images at 3.84 μm spatial resolution over a 245 μm field of view in the near-infrared regime. Leveraging a lightweight residual network to combat modal scrambling, MMF-SPCM successfully reconstructs amplitude and phase information of both artificial targets and stained/unstained biological tissues. These results mark, to our knowledge, the first demonstration of complex-field observation through an MMF without camera-based reliance, opening a practical path toward needle-like endoscopic tools for label-free histopathology, intraoperative guidance, and functional imaging in vivo.