Multi-Wavelength Laser Diode with Shared Amplifier for High Brightness
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Solution Overview
Problem
Existing wavelength-locked multimode pumps for kW fiber lasers are costly and inefficient due to high optical losses, sensitivity to grating shape, and unfavorable brightness scaling, leading to limited power output and increased costs per watt.
Innovation Solution
A monolithic diode chip design with multiple grating-locked, singlemode oscillators coupled into a shared amplifier structure, where seed beams diverge and overlap to uniformly fill the amplifier region, enabling efficient gain extraction and reducing filamentation, and utilizing wavelength beam combining (WBC) for enhanced brightness without sacrificing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If existing wavelength-locked multimode pumps are used, then power output can be achieved, but optical losses are high and brightness scaling is unfavorable
Solution Approach 1:
The pump source is segmented into multiple independent singlemode oscillators (e.g., 7 oscillators) that each generate a narrow linewidth seed beam. These segmented oscillators are then coupled into a shared amplifier structure, allowing each oscillator to operate efficiently with minimal optical losses while collectively delivering high power output through the amplifier.
Solution Approach 2:
Multiple singlemode oscillators are merged into a shared amplifier structure where their seed beams are combined and amplified together. This merging allows the system to achieve high power output while maintaining the low optical losses of individual singlemode oscillators, and the amplified beams are then wavelength-beam combined to achieve high brightness scaling.
2Power
If multimode oscillators are used, then power output is achieved, but beam quality degrades and filamentation occurs
Solution Approach 1:
Instead of using a single multimode oscillator that produces poor beam quality and filamentation, the system segments the oscillation into multiple independent singlemode oscillators. Each oscillator produces a high-quality singlemode beam, and when these are combined through the shared amplifier, the result is high power output without the beam quality degradation or filamentation that occurs in multimode systems.
3Reliability
If grating-locked oscillators are used, then wavelength stability is improved, but sensitivity to grating shape increases
Solution Approach 1:
The wavelength locking function is segmented and distributed across multiple independent singlemode oscillators, each with its own grating. This segmentation allows each oscillator to achieve wavelength stability independently while the overall system benefits from the redundancy and independence of multiple locked oscillators, reducing the impact of grating shape sensitivity on any single oscillator.
4Power
If conventional MOPA design is used, then high power is achieved, but device complexity increases
Solution Approach 1:
Multiple singlemode oscillators are merged into a shared amplifier structure, consolidating what would otherwise require multiple separate MOPA systems. This merging achieves high power output while reducing device complexity by sharing the amplifier infrastructure across multiple oscillators, rather than requiring independent amplifiers for each oscillator.
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
The design achieves high-brightness, low-cost operation with reduced filamentation and increased power scalability, maintaining uniform optical profiles and beam quality, making it suitable for kW fiber laser applications.
Implementation Method 1
the multiple seed beams that have the different wavelengths impinge upon the dispersive element at different incidence angles, and wherein the dispersive element is arranged to transmit the multiple seed beams at respective angles that cause the multiple seed beams to overlap in an output beam
Implementation Method 2
multiple grating-locked singlemode oscillators configured to transmit multiple seed beams having different wavelengths into a shared amplifier structure
Implementation Method 3
an optical amplifier configured to increase the output power while preserving the main properties of the master oscillator
Data Source
AI summary
In some implementations, an optical device (e.g., a monolithic master oscillator power amplifier (MOPA) diode) may include a first facet, one or more gratings, an amplifier structure terminated with a second facet, and an oscillator array that includes multiple singlemode oscillators coupled to the first facet and to the one or more gratings. In some implementations, the multiple singlemode oscillators may be configured to generate multiple seed beams and to transmit the multiple seed beams into the amplifier structure through the one or more gratings.