Coherent Pulse Stacking Amplification (CPSA) is a new time-domain coherent addition
technique that overcomes the limitations on pulse energies achievable from optical amplifiers. It
uses reflecting resonators to transform a sequence of phase- and amplitude-modulated optical
pulses into a single output pulse enabling high pulse energy for fiber lasers.
This thesis focuses on utilizing efficient algorithms for stabilization and optimization
aspects of CPSA and developing a robust, scalable, and distributed digital control system with
firmware and software integration for algorithms, to support the CPS (Coherent Pulse Stacking)
application. We have presented the theoretical foundation of the stochastic parallel gradient
descent (SPGD) for phase stabilization, discussed its performance criteria, its convergence, and its
stability. We have presented our software and hardware development for time-domain coherent
combing stabilization (specifically, an FPGA (Field Programmable Gate Array)-based Control
system with software/firmware development to support stabilization and optimization algorithms).
Analytical formulations of output stacked pulse profile as a function of input pulse train amplitudes
and phase and stacker cavity parameters have been derived so as to build up a foundation for a
GTI (Gires-Tournois-Interferometer) Cavity-based noise measurement technique. Time-domain
and frequency domain characterization techniques have been presented to analyze phase and
amplitude noise in the stacking system. Stacking sensitivity to errors in different control
parameters (stacker cavity phase, pulse amplitude, and phases) for different stacker configurations
have been analyzed. Noise measurement results using GTI cavities with different round-trip time
has have been presented and we have shown how effectively the stacking phase noise in the system
can be reduced by improving the noise performance of the mode-locked oscillator. Simulation and
Experimental results for stabilizing different stacker configurations have been presented. Finally
an algorithmic control system along with software/hardware development for optimizing
amplitudes and phases of the input burst has been implemented to increase stacking fidelity. A
complete detailed description, and simulation of the Genetic Algorithm as an alternative algorithm
for optimizing the stacked pulse fidelity has been presented. Comparison between SPGD and
Genetic Algorithm results has been done to evaluate their performance.
To summarize, this thesis provides theoretical, experimental, and implementation aspects
of controlling CPSA system by introducing efficient control algorithms and developing a turn-key
digital control system which is scalable to large number of stacker cavities.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147664/1/msheikhs_1.pd
