Novel Designs and Coupling Schemes for Affordable High Energy Laser Modules

Abstract : This multi-disciplinary research effort developed new classes of compact, highly-doped Er/Yb phosphate-doped glass fibers as high power, low noise single wavelength, single mode oscillators. Three world record powers in low-noise, single frequency laser oscillators at the eyesafe wavelength of 1.55 micrometers were reported. The project vertically integrated fabrication, testing, and optimization of all components necessary for manufacturing of fiber laser units including highly doped specialty glasses, fiber preforms, fiber drawing techniques, fiber Bragg gratings, fiber facet coatings, and fusion splicing of fiber components. A novel stack and draw technique produced single and multicore geometries including index guides and micro-structured single and multiple core fibers. Ulltra-short pulse generation in these phosphate fibers yielded world record peak intensities and novel applications. The MIT partners developed a novel class of surface emitting fiber lasers based on 1D photonic bandgap confinement. A new class of optically-pumped high-power, high brightness semiconductor vertical-external-cavity surface emitting laser emitting around 980nm were designed using a novel epitaxial quantum design approach and demonstrated experimentally. Power scaling methods such as spectral beam combining and cascaded intra-cavity semiconductor chips were demonstrated as well as visible light generation via intra-cavity second harmonic generation. Over 70 articles were published in peer-reviewed journals.