Influence of non-linear index on coherent passive beam combining of fiber lasers

A. P. Napartovich; N. N. Elkin; D. V. Vysotsky

doi:10.1117/12.874160

10 February 2011 Influence of non-linear index on coherent passive beam combining of fiber lasers

A. P. Napartovich, N. N. Elkin, D. V. Vysotsky

Proceedings Volume 7914, Fiber Lasers VIII: Technology, Systems, and Applications; 791428 (2011) https://doi.org/10.1117/12.874160
Event: SPIE LASE, 2011, San Francisco, California, United States

Abstract

Coherent laser beam combining is potentially attractive way to increase the output beam brightness beyond the limits imposed on single-mode lasers by technological problems. Passive phase locking does not need complex external management. A specific feature of fiber amplifiers and lasers is that they possess optical path differences of many wavelengths magnitude. Cold-cavity theory of coherent laser beam combining predicts in this case rather low efficiency of beam combining even for an array of 8 lasers. Experiments, in contrast, demonstrated in such systems that high degree of phasing takes place for up to 20 lasers in an array. Possible explanation of this discrepancy may be associated with a number of factors. These factors are: gain saturation, intensity-dependent index, laser wavelength self-adjustment within the gain bandwidth. Besides, high degree of phase-locking can be established in self-sustained pulse periodic or spiky regime. Our approach takes injection controlled laser as a base unit of an ensemble. Beams from the neighboring lasers are injected into the reference laser in the array. Then a relationship between reference laser characteristics and whole wave field parameters can be found. As an example, fiber laser array with global coupling is numerically simulated with laser wavelength scanned within the gain bandwidth. Non-linear index is found to improve essentially passive phasing efficiency independent of the non-linearity sign.

Citation Download Citation

A. P. Napartovich, N. N. Elkin, and D. V. Vysotsky "Influence of non-linear index on coherent passive beam combining of fiber lasers", Proc. SPIE 7914, Fiber Lasers VIII: Technology, Systems, and Applications, 791428 (10 February 2011); https://doi.org/10.1117/12.874160

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