Super-resolution multimode fiber imaging with an untrained neural network.

Multimode fiber endoscopes provide extreme miniaturization of imaging components for minimally invasive deep tissue imaging. Typically, such fiber systems suffer from low spatial resolution and long measurement time. Fast super-resolution imaging through a multimode fiber has been achieved by using computational optimization algorithms with hand-picked priors. However, machine learning reconstruction approaches offer the promise of better priors, but require large training datasets and therefore long and unpractical pre-calibration time. Here we report a method of multimode fiber imaging based on unsupervised learning with untrained neural networks. The proposed approach solves the ill-posed inverse problem by not relying on any pre-training process. We have demonstrated both theoretically and experimentally that untrained neural networks enhance the imaging quality and provide sub-diffraction spatial resolution of the multimode fiber imaging system.