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Mode-converters for rectangular-core fiber amplifiers to achieve diffraction-limited power scaling.
Arun Kumar Sridharan1, Paul H Pax, John E Heebner
1Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA. sridharan1@llnl.gov
Optics Express
|December 25, 2012
Summary
Researchers developed a novel diffractive optic system to convert light modes for high-power fiber amplifiers. This technique efficiently converts between the fundamental TEM(00) mode and higher-order modes (HOM) in ribbon fibers, achieving record efficiencies.
Area of Science:
- Optics and Photonics
- Fiber Lasers and Amplifiers
- Mode Conversion Technology
Background:
- Rectangular-core (ribbon) fibers offer potential for higher average power scaling compared to traditional circular-core fibers.
- Efficient interfacing of ribbon fiber amplifiers with standard laser sources and applications requires effective mode conversion.
- Existing methods for mode conversion in such systems are limited.
Purpose of the Study:
- To demonstrate a novel mode conversion technique for interfacing TEM(00) mode seed sources with higher-order mode (HOM) ribbon fiber amplifiers.
- To achieve efficient conversion of HOM back to a diffraction-limited TEM(00) mode for end-user applications.
- To present the first simulation and experimental validation of this diffractive optic-based mode conversion system.
Main Methods:
- Utilized two diffractive optic elements positioned in conjugate Fourier planes for mode conversion.
- Simulated the conversion of a diffraction-limited TEM(00) mode to the HOM of a ribbon fiber.
- Experimentally demonstrated the conversion of a single HOM in a ribbon fiber back to a TEM(00) mode.
Main Results:
- Achieved approximately 84% mode conversion efficiency from TEM(00) to HOM, with theoretical potential approaching 100%.
- Demonstrated a record 80.5% conversion efficiency for converting HOM back to a diffraction-limited TEM(00) mode.
- Validated the effectiveness of the diffractive optic approach for high-power fiber amplifier interfacing.
Conclusions:
- The developed diffractive optic system provides an efficient solution for mode conversion in ribbon fiber amplifiers.
- This technology enables the use of ribbon fibers for high-power laser applications requiring specific mode outputs.
- The demonstrated efficiencies represent a significant advancement in the field of fiber optic mode manipulation.
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