Fiber Laser Pump Diode Current Tuning for Higher Wall-Plug Efficiency
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Solution Overview
Problem
Existing high power fiber lasers suffer from low wall-plug efficiency (WPE) ranging from 25% to 35%, primarily due to inefficient operation of laser diodes and other components, with significant losses from mechanisms like Below Threshold, Band alignment, Carrier leakage, Scattering, Absorption, and Joule heating, necessitating improved configuration to enhance overall efficiency.
Innovation Solution
The fiber laser system is configured with laser diodes operating below their current threshold, optimizing individual components such as PLDs, fiber gain blocks, and other elements to achieve maximum efficiency, with PLDs operating at 4 to 6 A current, fiber blocks at 80% to 90% optical efficiency, and other components at their respective optimal ranges, resulting in a combined WPE of up to 55%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If laser diodes operate at high current to increase output power, then power output is improved, but wall-plug efficiency deteriorates due to Below Threshold, Band alignment, Carrier leakage, Scattering, Absorption, and Joule heating losses
Solution Approach 1:
The patent applies parameter changes by operating laser diodes at optimized current levels (4 to 6 A) rather than maximum current, and by adjusting the wavelength matching between pump diodes and fiber laser absorption lines. This optimization of operating parameters reduces energy losses from Below Threshold, Band alignment, Carrier leakage, Scattering, Absorption, and Joule heating mechanisms while maintaining high output power, thereby improving wall-plug efficiency to above 45%
Solution Approach 2:
The patent implements dynamic optimization by using electronic control to adjust the operating current of each laser diode based on real-time performance monitoring. The system dynamically balances the output power requirements with efficiency considerations, allowing the laser diodes to operate at optimal efficiency points rather than fixed high-current modes, thus resolving the contradiction between power output and energy efficiency
2Use of energy by moving object
If pump semiconductor laser diodes operate at high efficiency (50-70% electrical-to-optical), then electrical-to-optical conversion is improved, but overall system wall-plug efficiency deteriorates due to additional losses in thermal control, electronics, and AC-DC power conversion
Solution Approach 1:
The patent implements feedback mechanisms through electronic monitoring and control systems that track the performance of pump semiconductor laser diodes and adjust their operation accordingly. By monitoring electrical-to-optical conversion efficiency in real-time and providing feedback to the control system, the patent optimizes the operating parameters to minimize cumulative losses from thermal control, electronics, and AC-DC power conversion, thereby improving overall wall-plug efficiency
Solution Approach 2:
The patent changes operational parameters by optimizing the electrical-to-optical conversion efficiency of pump semiconductor laser diodes to 50-70% and coordinating this with optimized AC-DC power conversion and thermal management parameters. By systematically adjusting these parameters across different system components, the patent reduces cumulative energy losses and achieves overall wall-plug efficiency above 45%
3Loss of energy
If laser diodes are operated below current threshold to reduce energy waste, then wall-plug efficiency is improved, but output power is reduced
Solution Approach 1:
The patent applies partial action by operating laser diodes at current levels (4 to 6 A) that are below the traditional threshold for maximum power output but are optimized to achieve peak efficiency. By using multiple laser diodes in parallel at these optimized partial current levels, the system achieves high overall output power while minimizing energy waste from Below Threshold, Band alignment, Carrier leakage, Scattering, Absorption, and Joule heating mechanisms, thereby improving wall-plug efficiency
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 optimized configuration achieves a WPE of 55%, reducing power consumption, operation costs, and thermal load, enhancing reliability and reducing greenhouse gas emissions, while extending the lifetime of laser diodes and simplifying cooling systems.
Implementation Method 1
The efficiency of the pump semiconductor laser diodes is high, with on the order of 50% electrical-to-optical efficiency. Laboratory results are even better, with 70% or even more of the electrical pump energy being converted into light.
Implementation Method 2
The optical-to-optical conversion efficiency depends on a small quantum defect, high excitation and extraction efficiency and background loss. It can be on the order of 60% to 90%.
Implementation Method 3
When a wavelength of this output is matched carefully to the fiber laser's absorption line, the result is the enhanced wall plug efficiency ('WPE') of the pumped fiber laser.
Data Source
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AI summary
The inventive laser is configured with a plurality of pigtailed multimode (MM) diode lasers each receiving a direct input current at a room temperature which is maintained to be within a 20-25° C inside the housing of the laser. The diode lasers each are configured to operate at a desired wavelength in an optimal operational range, in which the diode laser operates with a WPE range between 63% and 75%. The direct current inputted in each diode laser is selected to be below a threshold at an efficiency curve of the diode laser after which the efficiency of the diode laser starts decreasing while an output power of the diode laser continues to increase. The laser is further configured with a fiber gain block having an active fiber medium which is pumped with the cumulative pump output and operative to emit a laser output in a power range between hundreds of watts and tens and even hundreds of kilowatts at the desired wavelength in an optimal operation range. The optimal operational ranges of respective MM diode lasers and fiber gain block are matched to achieve a superposition of respective efficiency maximums providing an overall maximum system efficiency up to 55%.