The mechanisms of nonlinear phase-locking of a large fiber amplifier array are analyzed. The preference is given to the most suitable configuration for a coherent coupling of thousands of fundamental spatial mode fiber beams into a single smooth beam ready for chirped pulse compression. It is shown that a Michelson phase-conjugating configuration with double passage through an array of fiber amplifiers has the definite advantage compared to a one-way fiber array coupled in a Mach–Zehnder configuration. Regardless of the amount of synchronized fiber amplifiers, the Michelson phase-conjugating interferometer is expected to do a perfect compensation of the phase-piston errors and collimation of backwardly amplified fiber beams on an entrance/output beam splitter. In both configurations, the nonlinear transformation of the stretched pulse envelope, due to gain saturation, is capable of randomizing the position of chirp inside an envelope; thus it may reduce the visibility of the interference pattern at an output beam splitter. Certain advantages are inherent to the sech-form temporal envelope because of the exponential precursor and self-similar propagation in gain medium. The Gaussian envelope is significantly compressed in a deep gain saturation regime, and the frequency chirp position inside pulse envelope is more deformed.
© 2014 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
J. Opt. Soc. Am. B 13(8) 1748-1757 (1996)
Cecile Joubert, Marie L. Roblin, and Roger Grousson
Appl. Opt. 28(21) 4604-4612 (1989)
Amos Hardy and Yaron Silberberg
J. Opt. Soc. Am. 73(5) 594-599 (1983)