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Linewidth reduced cascaded Raman fiber lasers and their harmonic conversion for visible laser sources
Optics Express
|June 11, 2024
Summary
Cascaded Raman Fiber Lasers (CRFLs) achieve narrow linewidths and tunable output using a novel dual feedback mechanism. This innovation enables efficient wavelength tuning across the Near-Infrared spectrum for various applications.
Area of Science:
- Optics and Photonics
- Laser Physics
- Materials Science
Background:
- Cascaded Raman Fiber Lasers (CRFLs) offer wavelength versatility in the Near-Infrared (NIR) but typically suffer from broad linewidths.
- Broadband feedback in conventional CRFLs allows tunability but broadens spectral output.
- Reducing linewidth without sacrificing tunability is crucial for advanced laser applications.
Purpose of the Study:
- To develop a dual feedback mechanism for CRFLs to significantly reduce linewidth while maintaining wavelength tunability.
- To explore the application of linewidth-narrowed CRFLs in frequency doubling for visible light generation.
Main Methods:
- Implementation of a dual feedback system combining broadband feedback (flat cleave) with filtered feedback (grating filter).
- Utilizing the dual feedback mechanism in CRFLs up to the 6th Raman shift (1100-1500 nm).
- Performing frequency doubling experiments on the linewidth-narrowed CRFL output.
Main Results:
- Achieved substantial linewidth reduction in CRFLs across multiple Raman shifts (up to 6th).
- Demonstrated multi-watt in-band output power with fine wavelength tuning within Raman Stokes bands.
- Generated over 100 mW of wavelength-tunable yellow-green and yellow light via frequency doubling with enhanced efficiency.
Conclusions:
- The proposed dual feedback mechanism effectively narrows the linewidth of CRFLs without compromising tunability.
- This technique provides a pathway to high-power, narrow-linewidth NIR sources with potential for extension to broader wavelength ranges.
- Linewidth-narrowed CRFLs are promising for efficient frequency conversion applications, enabling tunable visible light generation.
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