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Bandwidth and stability of the stochastic parallel gradient descent algorithm for phase control in coherent beam
Applied Optics
|June 18, 2021
Summary
This study analyzes the stochastic parallel gradient descent (SPGD) algorithm for coherent beam combination, revealing its bandwidth and stability limits. The findings help estimate achievable phase control bandwidth in such systems.
Area of Science:
- Optics and Photonics
- Control Systems Engineering
Background:
- Coherent beam combination (CBC) is crucial for high-power laser systems.
- The stochastic parallel gradient descent (SPGD) algorithm is a common method for phase control in CBC.
- Understanding the operational limits of SPGD is essential for system optimization.
Purpose of the Study:
- To investigate the bandwidth and stability limitations of the SPGD algorithm in CBC.
- To develop an analytical model for the SPGD phase control loop.
- To validate the model against experimental and simulation data.
Main Methods:
- Derivation of an analytical model for the SPGD phase control loop.
- Experimental validation using a four-sub-beam tiled CBC setup with fiber-optic collimators.
- Numerical simulations and comparison with existing literature.
Main Results:
- The analytical model accurately predicts the performance of the SPGD algorithm.
- Favorable comparison of the model with experimental results, numerical simulations, and prior studies.
- Quantification of the bandwidth and stability limits of SPGD for CBC.
Conclusions:
- The developed analytical model provides a reliable tool for assessing SPGD performance in CBC systems.
- Results enable estimation of the achievable phase control bandwidth for CBC systems utilizing SPGD.
- This research contributes to the design and optimization of high-performance laser beam combination technologies.
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