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Diffractive coherent combining of a 2.5 kW fiber laser array into a 1.9 kW Gaussian beam
Shawn M Redmond1, Daniel J Ripin, Charles X Yu
1Massachusetts Institute of Technology, Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA. s.redmond@ll.mit.edu
Optics Letters
|July 25, 2012
Summary
Researchers coherently combined five fiber amplifiers into a single high-power beam. This fiber amplifier combination achieved superior beam quality and high output power, demonstrating a promising technique for laser technology.
Area of Science:
- Optics and Photonics
- Laser Technology
- Fiber Optics
Background:
- High-power fiber lasers are crucial for various industrial and scientific applications.
- Coherent beam combination is an effective method for scaling laser power while maintaining beam quality.
Purpose of the Study:
- To demonstrate the coherent combination of multiple high-power fiber amplifiers.
- To evaluate the beam quality and combining efficiency of the system.
Main Methods:
- Five 500 W fiber amplifiers were used as input sources.
- A diffractive optical element was employed as the beam combiner.
- The output beam quality (M-squared) and combining efficiency were measured.
Main Results:
- A combined output power of 1.93 kW was achieved.
- The resulting beam quality (M-squared=1.1) surpassed that of the individual amplifiers.
- Combining efficiency reached approximately 90% at low power, decreasing to 79% at full power due to thermal effects.
Conclusions:
- Coherent combination of fiber amplifiers is feasible for generating high-power laser beams.
- The diffractive optical element combiner effectively improved beam quality.
- Thermal expansion of the fiber tip array at high power impacts combining efficiency and requires further mitigation strategies.
