Parallel random fiber Bragg gratings in cladding for a narrow linewidth random fiber laser

Area of Science:

• Photonics and Laser Technology
• Optical Fiber Sensing and Communications

Background:

• Random fiber lasers (RFLs) are gaining attention for their unique spectral properties.
• Conventional RFLs often face limitations in linewidth and system integration.
• Developing advanced filtering mechanisms is crucial for enhancing RFL performance.

Purpose of the Study:

• To introduce a novel filtering device for RFLs: parallel-cladding random fiber Bragg gratings (Parallel-CLRFBGs).
• To investigate the impact of Parallel-CLRFBGs on light scattering, interference, and feedback in RFLs.
• To compare the performance of RFLs utilizing Parallel-CLRFBGs with conventional RFL configurations.

Main Methods:

• Fabrication of Parallel-CLRFBGs in single-mode fiber (SMF) using femtosecond-infrared (fs-IR) laser point-by-point inscription.
• Integration of Parallel-CLRFBGs into a hybrid cavity RFL system.
• Characterization of RFL output linewidth and comparison with conventional core-random fiber Bragg gratings (Core-RFBGs).

Main Results:

• Parallel-CLRFBGs effectively control light scattering and interference, boosting backward Rayleigh scattering for enhanced feedback.
• The use of sub-centimeter cladding-aligned gratings in parallel improves laser system integration.
• RFLs employing Parallel-CLRFBGs achieved a narrow linewidth output of 138 Hz, approximately half that of RFLs with Core-RFBGs.

Conclusions:

• Parallel-CLRFBGs represent a novel and effective filtering device for RFLs.
• This new grating configuration significantly narrows the output linewidth of RFLs.
• Parallel-CLRFBGs offer advantages in terms of laser system integration and spectral performance.