Product Code: ICA11_1809

An Efficient Method for Enhancing the Filling Factor of the Aperture for Coherent-Beaming-Combining (CBC) using Thin-Film Coated Glass
Authors:
Si-si Zhao, Beijing University of Technology; Beijing Peoples Republic of China
Zheng-yu Ye, Beijing University of Technology; Beijing Peoples Republic of China
Zhi-yong Wang, Beijing University of Technology; Beijing Peoples Republic of China
Presented at ICALEO 2011

Aperture technology, which influences the combining efficiency, is the key factor for Coherent-Beam-Combining (CBC). By using beam combiner with high performances, coherent combining of fiber lasers can provide the chance to increase the output intensity more efficiently. We present a method to manufacture the beam combiner for CBC by using a thin-film coated glass plate. This method can increase the effective filling factor of aperture, and therefore eliminate far-field side-lobes by enlarging the number of sub-apertures and decreasing the distance between the sub-apertures for an output aperture with a constant size. The fabrication of this thin-film coated glass costs less and the coated glass has better stability than other beam combiners. In order to minimize the insertion loss and obtain high efficiency for CBC, we also exploit physical optics propagation combined with geometrical ray-tracing for modeling and optimizing the reflectivity distribution, the position, the thickness and the lithography resolution of the coated glass. Theoretically, this method can raise the coherent combining efficiency almost to 100% while maintaining near diffractive-limitation (DL) beam quality (BQ). Additionally, based on this method, a new conception of Multiple-beam Interference of Multi-beams is offered. The concept to our knowledge was not reported before.