Optical manipulation, beam-shaping and scanner-free bright-field and dark-field imaging via multimode optical fibre

We present a powerful approach towards full understanding of laser light propagation through multimode optical fibres and control of the light at the fibre output. Transmission of light within a multimode fibre introduces randomization of laser beam amplitude, phase and polarization. We discuss the importance of each of these factors and introduce an experimental geometry allowing full analysis of the light transmission through the multimode fibre and subsequent beam-shaping using a single spatial light modulator. We show that using this approach one can generate an arbitrary output optical field within the accessible field of view and range of spatial frequencies given by fibre core diameter and numerical aperture, respectively, that contains over 80% of the total available power. We present applications of these approaches in bio-medical photonics and imaging. We show the confinement and manipulation of a number of microparticles using the output field of the multimode fibre. Further we demonstrate the modalities of bright-field and dark-field imaging at acquisition rates allowing observation of dynamic processes such as Brownian motion of mesoscopic particles.