Coherent Beam Combining with Parallel Phase and Polarization Locking
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Solution Overview
Problem
High power lasers, such as amplification fiber lasers, face challenges in maintaining near diffraction limit beam quality due to Stimulated Brillouin Scattering, Stimulated Raman Scattering, and modal thermal instability, which are exacerbated by phase and polarization instability in multiple fiber lasers used for coherent beam combining.
Innovation Solution
A closed-loop parallel phase locking and polarization locking mechanism is implemented using a reference optical beam and optical detectors to synchronize phases and polarizations of multiple input optical beams, allowing for rapid and automatic locking without calculating optimal phases or polarizations, thereby maintaining high beam quality under environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple fiber lasers are combined to increase power output, then power output is improved, but beam quality deteriorates due to phase and polarization instability
Solution Approach 1:
The patent implements a feedback mechanism where optical detectors continuously monitor the combined beam's phase and polarization states, and control elements (such as phase shifters and polarization controllers) automatically adjust the individual fiber laser beams to maintain optimal coherence. This closed-loop feedback system resolves the contradiction by dynamically compensating for phase and polarization instabilities that would otherwise degrade beam quality when combining multiple high-power fiber lasers.
2Manufacturing precision
If phase locking mechanism is implemented to maintain beam quality, then beam quality is improved, but device complexity increases
Solution Approach 1:
The patent introduces intermediary components including optical detectors that measure beam parameters and control elements (phase shifters, polarization controllers) that mediate between the individual fiber lasers and the combined beam. These intermediaries simplify the overall system by providing automated control rather than requiring complex manual alignment and stabilization mechanisms, thus resolving the contradiction between maintaining beam quality and reducing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the combination of multiple input optical beams into a high-quality, high-power coherent beam that is resilient to environmental fluctuations, achieving improved far-field spatial and spectral coherence and beam steering capabilities.
Implementation Method 1
directing the reference optical beam, such that the reference optical beam interferes with the sample optical beams, generating a plurality of corresponding optical interference signals
Data Source
AI summary
Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.