Four-channel prototype using coherent combining of ultrashort laser pulses for dipole configuration approximation

This paper presents a four-channel prototype system for the geometric combining and coherent addition of tightly focused femtosecond laser radiation into a standing-wave field configuration.

A stabilization system for beam pointing and relative phase of the four optical channels has been implemented, and its performance has been experimentally demonstrated.

To characterize the standing-wave electromagnetic field distribution at the main focus of the system, an original measurement technique based on a fiber subwavelength optical probe has been employed.

This work has been conducted in support of the exawatt-scale XCELS project.