Simplified Design of Optical Elements for Filled-Aperture Coherent Beam Combination

TL;DR

This paper introduces a simplified design approach for segmented mirror splitters used in coherent beam combination, reducing manufacturing complexity while maintaining high efficiency for multiple beams.

Contribution

It proposes a novel optimization method for simplified optical designs with fewer coatings, enabling scalable high-efficiency beam combination.

Findings

High combination efficiency with only 1-3 unique coatings.

Simplified designs are effective for several tens of beams.

Potential inhomogeneous power distribution may cause some loss.

Abstract

A simplification strategy for Segmented Mirror Splitters (SMS) used as beam combiners is presented. These devices are useful for compact beam division and combination of linear and 2-D arrays. However, the standard design requires unique thin-film coating sections for each input beam and thus potential for scaling to high beam-counts is limited due to manufacturing complexity. Taking advantage of the relative insensitivity of the beam combination process to amplitude variations, numerical techniques are used to optimize highly-simplified designs with only one, two or three unique coatings. It is demonstrated that with correctly chosen coating reflectivities, the simplified optics are capable of high combination efficiency for several tens of beams. The performance of these optics as beamsplitters in multicore fiber amplifier systems is analyzed, and inhomogeneous power distribution of the simplified designs is noted as a potential source of combining loss in such systems. These simplified designs may facilitate further scaling of filled-aperture coherently combined systems.