KEYWORDS: Phase shift keying, Optical components, Photodetectors, Phase modulation, Signal processing, Modulation, High power fiber amplifiers, Optical amplifiers, Phase measurement, Signal to noise ratio
We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by
Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element
amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the
phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent
results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently
combined.
Two approaches to two- and three-tone seeding of high power ytterbium-doped fiber amplifiers are investigated using a
symbolic and numerical code that solves a two point boundary problem consisting of a 12×12 system of nonlinear
differential equations. Optimization of amplifier action is considered in relation to the two most dominant nonlinear
effects: stimulated Brillouin scattering and four-wave mixing. One approach uses a large wavelength separation among
the input seed beams, while in the other approach the seeds are separated by precisely twice the Brillouin shift. It is
found that for both techniques significant increase in amplifier output can be obtained, although for the latter case a
substantial amount of power is generated in the four-wave mixing sidebands.
We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by
Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element
amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the
phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent
results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently
combined.
A new technique for mitigating stimulated Brillouin scattering (SBS) effects in narrow-linewidth Yb-doped fiber
amplifiers is demonstrated with a model that reduces to solving an 8×8 system of coupled nonlinear equations with the
gain, SBS, and four-wave mixing (FMW) incorporated into the model. This technique uses two seed signals, or 'two-tones',
with each tone reaching its SBS threshold almost independently and thus increasing the overall threshold for SBS
in the fiber amplifier. The wavelength separation of these signals is also selected to avoid FWM, which in this case
possesses the next lowest nonlinear effects threshold. This model predicts an output power increase of 86% (at SBS
threshold with no signs of FWM) for a 'two-tone' amplifier with seed signals at 1064nm and 1068nm, compared to a
conventional fiber amplifier with a single 1064nm seed. The model is also used to simulate an SBS-suppressing fiber
amplifier to test the regime where FWM is the limiting factor. In this case, an optimum wavelength separation of 3nm to
10nm prevents FWM from reaching threshold. The optimum ratio of the input power for the two seed signals in 'two-tone'
amplification is also tested. Future experimental verification of this 'two-tone' technique is discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.