Raman Fiber Lasers and Amplifiers Based on Multimode Graded-Index Fibers and Their Application to Beam Cleanup

Abstract

Raman fiber lasers (RFLs) and Raman fiber amplifiers (RFAs) in multimode fibers were explored. The RFL based on a graded-index fiber was shown to be very efficient relative to RFLs based on singlemode fibers. Several configurations of the RFL were examined; the beam quality of the Stokes beam depended on the reflectivity of the output coupler and the Stokes power. When used as a beam combiner, the RFL was a highly efficient brightness converter. RFL configurations which used dichroic mirrors were shown to be potentially useful for RFLs based on very large fibers. The forward- and backward-seeded geometries of an RFA based on a graded-index fiber were examined. The beam quality of the output was observed to depend on the beam quality of the input. A numerical model explains this behavior in terms of mode competition and explains why beam cleanup occurs in graded-index fibers but not in step-index fibers. The spectrum of the forward-seeded geometry was superior to the spectrum of the backward-seeded geometry. The RFA was used as a beam combiner.

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 2007
Accession Number
ADA469788

Entities

People

  • Nathan B. Terry

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Chemical Oxygen Iodine Lasers
  • Diffraction
  • Dye Lasers
  • Frequency Combs
  • Laser Applications
  • Laser Beams
  • Laser Diodes
  • Laser Mediums
  • Lasers
  • Light (Electromagnetic Radiation)
  • Nonlinear Optics
  • Optical Fiber Lasers
  • Optical Materials
  • Optical Phenomena
  • Optics
  • Raman Fiber Lasers
  • Raman Lasers

Fields of Study

  • Physics

Readers

  • Optical Fiber Sensing and Electromagnetic Propagation.
  • Pulsed Power and Plasma Physics.

Technology Areas

  • Directed Energy