Stable and low-threshold random fiber laser via Anderson localization

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Erbium-doped fiber lasers are crucial for various applications.
• Achieving low thresholds and stable operation in random fiber lasers (RFLs) remains a challenge.
• Random feedback mechanisms are key to RFL development.

Purpose of the Study:

• To report a stable and low-threshold Er-doped random fiber laser (RFL).
• To utilize a femtosecond-laser-inscribed random-distributed-grating array (RDGA) for random feedback.
• To demonstrate a method for selecting RFL lasing modes.

Main Methods:

• Fabrication of an RDGA using femtosecond laser inscription.
• Numerical analysis of RDGA properties using the transfer matrix method.
• Integration of the RDGA into an Er-doped fiber laser cavity.
• Mode selection via stretching a fiber grating filter with axial strain.

Main Results:

• Achieved a significantly reduced laser threshold of 5.7 mW.
• Observed a narrow linewidth of ~0.4 pm near threshold due to Anderson localization.
• Demonstrated stable laser operation with minimal peak power jitter (<0.12 dB over 1 hour).
• RDGA exhibited a high reflectivity of 93.5% and improved laser quality factor (4 × 10^6).

Conclusions:

• The developed RDGA-based Er-doped RFL offers stable and low-threshold operation.
• Anderson localization in the RDGA enhances laser quality factor and performance.
• The proposed mode selection method provides precise control over lasing wavelengths.
• This work presents a promising platform for stable, tunable random fiber lasers.