Wavefront engineering for controlled structuring of far-field intensity and phase patterns from multimodal optical fibers

Abstract

Adaptive optics methods have long been used to perform complex light shaping at the output of a multimode fiber (MMF), with the specific aim of controlling the emitted beam in the near field and enabling the realization of a new generation of endoscopes based on a wide variety of spectroscopic techniques. Gaining control of other emission properties, including the far-field pattern and the phase of the generated beam, would open up the possibility for multimode fibers to act as miniaturized multi-beam steering components and to implement phase-encoded imaging and sensing. In this study, we employ phase modulation using a spatial light modulator at the input of a multimode fiber to generate multiple, low divergence rays with controlled angles and phase at the fiber output. Direct measurement of the output angle and the divergence and phase of the generated beams show how wavefront engineering can be employed to perform complex far-field structuring of the emission of a MMF.