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System design for coherent combined massive fiber laser array based on cascaded internal phase control.
Applied Optics
|January 6, 2023
Summary
A new cascaded internal phase-control technique enhances coherent beam combining (CBC) for high-power fiber laser systems. This method significantly improves control bandwidth and reduces phase errors in massive laser arrays.
Area of Science:
- Optics and Photonics
- Laser Physics
- High-Power Laser Systems
Background:
- Coherent beam combining (CBC) is crucial for scaling fiber laser output power while preserving beam quality.
- Phase detection and control present significant challenges in high-power CBC systems utilizing massive laser arrays.
- Existing methods, like the stochastic parallel gradient descent (SPGD) algorithm, face limitations in bandwidth and phase error reduction.
Purpose of the Study:
- To introduce and detail a novel cascaded phase-control technique for high-power coherent beam combining.
- To evaluate the performance of this technique, termed cascaded internal phase-control, using numerical simulations.
- To demonstrate its compatibility with massive laser arrays and its advantages over traditional methods.
Main Methods:
- Development of a cascaded internal phase-control technique based on internal phase detection and control.
- Numerical simulations employing the stochastic parallel gradient descent (SPGD) algorithm to validate the technique.
- Analysis of element expanding capacity and the absence of large-aperture optical devices in the phase detection system.
Main Results:
- The cascaded internal phase-control technique shows compatibility with massive laser arrays.
- Control bandwidth improvement of approximately seven times (120 steps) compared to the traditional SPGD algorithm (830 steps).
- Reduction in average root mean square residual phase error to 0.03 rad (λ/209) for a 259-channel array, a significant improvement over the traditional SPGD's 0.36 rad (λ/17).
Conclusions:
- The proposed cascaded internal phase-control technique offers superior performance in terms of control bandwidth and phase error reduction for high-power CBC systems.
- The technique's design, free from large-aperture optical devices, allows for flexible scaling of laser emitting systems.
- This work provides a valuable reference for the design and phase control of high-power massive laser array systems.
