Coherent Beam Combining Using Per-Channel Interference Phase 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 addressed by combining multiple optical beams using coherent beam combining techniques.
Innovation Solution
A method for locking phases of channel optical beams in a coherent beam combining system involves generating a reference optical beam, sampling optical beams, and sequentially changing the phase difference between the reference and channel optical beams to determine optimal phase shifts, allowing for phase locking based on intensity measurements and desired spatial phase distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple optical beams are combined to overcome physical limitations, then beam quality and power are improved, but phase stability and alignment precision deteriorate
Solution Approach 1:
The patent employs feedback mechanisms through phase locking systems that continuously monitor and adjust the phase of individual optical beams. Photodetectors measure interference patterns between reference and channel beams, generating error signals that drive phase actuators to maintain optimal phase relationships, thereby ensuring phase stability in high-power combined beams
Solution Approach 2:
A reference optical beam serves as an intermediary element that mediates the phase relationship between multiple channel beams. The reference beam interferes with each channel beam individually, providing a common phase reference that enables precise phase control and alignment across all combined beams
2Manufacturing precision
If phase locking mechanisms are implemented to stabilize beam phase, then beam quality is improved, but system complexity increases
Solution Approach 1:
The phase locking system is segmented into independent control channels, where each channel beam is controlled separately through individual phase actuators and photodetectors. This modular segmentation allows precise control of each beam while maintaining overall system manageability and reducing control complexity
Solution Approach 2:
The patent replaces mechanical alignment systems with optical feedback-based phase locking. Instead of mechanically adjusting beam paths and phases, the system uses optical interference measurements and electronic feedback to control phase, eliminating complex mechanical adjustment mechanisms
3Measurement precision
If discrete phase shifting is used to lock beam phase, then phase control precision is improved, but measurement and detection difficulty increases
Solution Approach 1:
The system introduces controlled oscillations in the reference beam phase at known frequencies. These oscillations modulate the interference signal at detectable frequencies, enabling precise phase measurement through frequency-domain detection and simplifying the extraction of phase information from interference patterns
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 high-quality, high-power coherent beam combining by stabilizing phase differences between optical beams, improving beam quality and steering capabilities while enduring environmental changes.
Implementation Method 1
causing optical interference between each part of the reference optical beam and a corresponding sample optical beam, generating thereby an array of corresponding interference optical 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.