Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

Publication: Research - peer-reviewJournal article – Annual report year: 2012

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High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. This improves the limiting factor of nonlinear effects, while maintaining good beam quality. Photonic crystal fibers allow realization of short LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber. However, achieving ultra low NA for single-mode (SM) guidance is challenging, and thus different design strategies must be applied to filter out higher order modes (HOMs). The novel distributed modal filtering (DMF) design presented here enables SM guidance, and previous results have shown a SM mode field diameter of 60 μm operating in a 20 nm SM bandwidth. The DMF rod fiber has high index ring-shaped inclusions acting as resonators enabling SM guidance through modal filtering of HOMs. Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared to previous results, achieved by utilizing the first band of cladding modes. This covers of a large fraction of the Yb emission band, where wavelengths of 1030 nm and 1064 nm can be included.
Original languageEnglish
JournalProceedings of SPIE, the International Society for Optical Engineering
Pages (from-to)82373P
StatePublished - 2012
EventSPIE Photonics West : Fiber Lasers IX: Technology, Systems, and Applications - San Francisco, CA, United States


ConferenceSPIE Photonics West : Fiber Lasers IX: Technology, Systems, and Applications
CountryUnited States
CitySan Francisco, CA
CitationsWeb of Science® Times Cited: 0


  • Fiber design, Photonic crystal fibers, Optical amplifiers
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ID: 7701898