Simple model to explain instabilities in passively-phased high-power fiber laser arrays

Conference · Sat Jan 01 00:00:00 EST 2011

OSTI ID:1081689

Bochove, Erik J. ^[1]; Shakir, Sami A. ^[2]; Aceves, Alejandro B. ^[3]; Braiman, Yehuda ^[4]; Deiterding, Ralf ^[4]; Miller, Casey A ^[4]; Colet, Pere R. ^[5]; Jacobo, Adrian ^[5]; Rhodes, Charles ^[6]

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1. Air Force Research Laboratory, Kirtland Air Force Base, NM
2. TASC, Inc.
3. Southern Methodist University, Dallas
4. ORNL
5. University of the Balearic Islands, Palma de Mallorca, Spain
6. Liberations Systems Management, Inc.

We propose a simple physical mechanism to explain observed instabilities in the dynamics of passively phased fiber amplifier arrays that arises from two properties: First that a weak phase disturbance of the output field of the array is converted into a strong intensity disturbance through the mode-selective feedback mechanism. Second, that this intensity fluctuation regenerates a phase fluctuation due to the nonlinear properties of the amplifying media. At sufficiently high operating power levels this cyclic disturbance continues to grow upon each cavity round trip, creating instability. This simple picture is supported by the results of a linear stability analysis of the set of propagation and population rate equations, which are in good agreement with observed critical power levels. A third level of quantitative confirmation was obtained by comparison to the results of numerical integration of the original set of nonlinear equations. This predicted instability is entirely a property of passively phased arrays of more than one element.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: Work for Others (WFO)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1081689
• Resource Relation: Conference: Conference EOO112: Diode-Pumped High Energy and High Power Lasers, Prague, Czech Republic, 20110418, 20110421
• Country of Publication: United States
• Language: English