High power orbital-angular-momentum beam generation system based on coherent beam array combination technique

TL;DR

This paper presents a novel high power orbital-angular-momentum beam generation system using coherent beam array combination, overcoming power limitations of traditional methods, with experimental validation demonstrating high accuracy and potential applications in optical communications and biomedical fields.

Contribution

Proposes and experimentally demonstrates a high power OAM beam generation system based on coherent beam array combination and piston-phase-array modulation, surpassing traditional power constraints.

Findings

Achieved high power OAM beams with residual phase errors below λ/30.

Successfully generated OAM of ±1 using piston-phase-array modulation.

Experimental results closely match theoretical predictions.

Abstract

High power orbital-angular-momentum (OAM) beam has dominant advantages in capacity increasing and data receiving for free-space optical communication systems at long distance. Utilizing coherent combination of beam array technique and helical phase approximation by piston-phase-array, we have proposed a generation system of high power novel beam carrying OAM, which could overcome power limitation of common vortex phase modulator and single beam. We have experimentally implemented a high power OAM beam by coherent beam combination (CBC) of a six-element hexagonal fiber amplifier array. We show that the CBC technique utilized to control the piston phase differences among the array beams has a high accuracy with residual phase errors superior to {\lambda}/30. On the premise of CBC, we have obtained novel vortex beams carrying OAM of +/- 1 by applying an additional piston-phase-array modulation on the corresponding beam array. The experimental results approximately coincide with the theoretical analysis. This work could be beneficial to the areas that need high power OAM beams, like ultra-distance free-space optical communications, biomedical treatments, powerful trapping and manipulation under deep potential well.