Reconfigurable structured light generation in a multicore fibre amplifier

Di Lin,Michalis N Zervas,Joel Carpenter,David J Richardson,Yutong Feng,Yongmin Jung,Saurabh Jain,Yujun Feng

doi:10.1038/s41467-020-17809-x

Abstract

Structured light, with spatially varying phase or polarization distributions, has given rise to many novel applications in fields ranging from optical communication to laser-based material processing. However the efficient and flexible generation of such beams from a compact laser source at practical output powers still remains a great challenge. Here we describe an approach capable of addressing this need based on the coherent combination of multiple tailored Gaussian beams emitted from a multicore fibre (MCF) amplifier. We report a proof-of-concept structured light generation experiment, using a cladding-pumped 7-core MCF amplifier as an integrated parallel amplifier array and a spatial light modulator (SLM) to actively control the amplitude, polarization and phase of the signal light input to each fibre core. We report the successful generation of various structured light beams including high-order linearly polarized spatial fibre modes, cylindrical vector (CV) beams and helical phase front optical vortex (OV) beams.

Highlights

Structured light, with spatially varying phase or polarization distributions, has given rise to many novel applications in fields ranging from optical communication to laser-based material processing
A few methods that provide some flexibility in mode selection have been implemented in solid-state lasers but generally this has been achieved at the cost of a high intra-cavity loss and the output powers have been limited by damage to the special optics used due to the high intra-cavity powers involved[23,24]
In this paper we experimentally demonstrate the generation of various forms of complex beam (including azimuthally phasechirped optical vortex (OV) beams and radially/azimuthally polarized cylindrical vector (CV) beams defined on the higher-order Poincaré sphere (HOPS)) by coherent combination of individually amplified signals in a multicore fibre (MCF) amplifier

Summary

Introduction

Structured light, with spatially varying phase or polarization distributions, has given rise to many novel applications in fields ranging from optical communication to laser-based material processing. Coherent beam combination (CBC) using signals from multiple (independent) parallel laser sources has recently been proposed as a promising way to form exotic beams that avoids the low damage threshold problem of such flexible and scalable beam shaping elements and has been investigated theoretically and experimentally[35,36,37,38,39,40,41] In this approach, the active beam control element(s) can be positioned before the amplifier(s) (where the power levels are relatively modest) to provide the control needed for active phase locking between the multiple output beams at the (higher power) system output. CBC from MCF amplifier/lasers has previously been successfully demonstrated as an effective way for power scaling of simple Gaussian beams[42,43,44]

Methods

Results

Conclusion