Random fiber laser based on artificially controlled backscattering fibers.

Area of Science:

• Laser Physics
• Nonlinear Optics
• Fiber Optics

Background:

• Traditional random fiber lasers (RFLs) rely on Rayleigh scattering in long single-mode fibers.
• These conventional RFLs require long fiber lengths (tens of kilometers) and exhibit high thresholds (watt level).
• The limitations stem from the low Rayleigh scattering coefficient in standard single-mode fibers.

Purpose of the Study:

• To propose and demonstrate a novel half-open-cavity random fiber laser (RFL).
• To utilize artificially controlled backscattering single-mode fiber to overcome limitations of traditional RFLs.
• To achieve a low threshold and efficient random lasing.

Main Methods:

• Fabrication of a half-open cavity RFL using a femtosecond laser.
• Incorporation of a fiber Bragg grating (1530 nm) and artificially controlled backscattering single-mode fiber segments (210 m, 310 m, 390 m).
• Pumping with a 980 nm laser diode through a 5 m erbium-doped fiber segment.

Main Results:

• Achieved low lasing thresholds of 25 mW and 30 mW for different fiber lengths.
• Demonstrated random lasing at 1530 nm with a high extinction ratio of 50 dB.
• Successfully created a novel RFL configuration with multiple short cavities.

Conclusions:

• The proposed half-open-cavity RFL design significantly reduces the lasing threshold compared to conventional RFLs.
• Artificially controlled backscattering fiber enables efficient random lasing in shorter fiber lengths.
• This advancement paves the way for more practical and accessible random fiber laser applications.