File:CoherentAddition.jpg

Summary
Example of the coherent addition (coherent combining) of 4 fiber lasers.

There are 100% reflection mirrors (Bragg reflectors) at the left hand side.

There are coiled laser amplifiers which can be realized as single-mode double-clad fibers; which are, perhaps, coiled. There is coherent coupler, which provides the splitting of modes of lases. Such a splitter has so many outputs, as inputs. Most of outputs are cleaved providing almost zero reflectivity, and only one provides significant feedback. This channed determines the modes with minimal losses. Such modes are common for all lasers, providing the coherent addition of lasers.

Dima, Shirakawa, Bisson, Ueda used this pic is some of drafts of our paper. You may use it too.