Mode Control in a Multimode Fiber Through Acquiring its Transmission Matrix from a Reference-less Optical System

TL;DR

This paper presents a reference-less optical system that uses complex semidefinite programming to acquire the transmission matrix of a multimode fiber, enabling mode control and compensation without interferometry.

Contribution

It introduces a novel method combining a simple imaging setup with convex optimization to determine the transmission matrix without a reference arm, advancing multimode fiber control.

Findings

Successful transmission matrix acquisition without interferometry

Effective mode modulation and control demonstrated

Potential applications in biomedical imaging and quantum communication

Abstract

A simple imaging system together with complex semidefinite programming is used to generate the transmission matrix of a multimode fiber. Once the transmission matrix is acquired, we can modulate the phase of the input signal to induce strong mode interference at the fiber output. The optical design does not contain a reference arm and no interferometric measurements are required. We use a phase-only spatial light modulator to shape the profile of the propagating modes and the output intensity at an individual pixel is monitored. The semidefinite program uses a convex optimization algorithm to generate the transmission matrix of the optical system using intensity only measurements. This simple yet powerful method can be used to compensate for modal dispersion in multimode fiber communication systems. It also yields great promises for the next generation biomedical imaging, quantum communication, and cryptography.