Accession Number : AD1031469


Title :   Stimulated Brillouin Scattering (SBS) Suppression and Long Delivery Fibers at the Multikilowatt Level with Chirped Seed Lasers


Descriptive Note : Technical Report,01 Feb 2013,31 Aug 2016


Corporate Author : US Army Research Laboratory Adelphi United States


Personal Author(s) : White, Jeffrey O ; Harfouche,Mark ; Edgecumbe,John ; Satyan,Naresh ; Rakuljic,George ; Yariv,Amnon


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1031469.pdf


Report Date : 16 Mar 2017


Pagination or Media Count : 26


Abstract : In a high-power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 m in 10 s can yield a frequency chirp of 5 1017 Hz/s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp and stabilize the output power. The simple and deterministic variation of phase with time preserves temporal coherence, in the sense that it is straightforward to coherently combine multiple amplifiers despite a large path-length mismatch. The seed bandwidth, as seen by the counterpropagating SBS, also increases linearly with fiber length, resulting in a nearly length-independent SBS threshold. Experimental results at the 1.6-kW level with a 19-m delivery fiber are presented. A numerical simulation is also presented.


Descriptors :   BRILLOUIN SCATTERING , VERTICAL CAVITY SURFACE EMITTING LASERS , fiber optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE