Frequency stabilized coherent Brillouin random fiber laser: theory and experiments

Area of Science:

• Photonics and Laser Technology
• Optical Engineering
• Materials Science

Background:

• Random fiber lasers offer unique properties but often lack coherence and directionality.
• Stimulated Brillouin scattering (SBS) and Rayleigh scattering are explored for laser gain and feedback mechanisms.
• Frequency stabilization is crucial for practical applications of random lasers.

Purpose of the Study:

• To construct and characterize a coherent random fiber laser with enhanced directionality and frequency stability.
• To investigate the role of a Fabry-Perot interferometer (FPI) in stabilizing the laser's output frequency.
• To demonstrate high-quality coherent random lasing using a low-power continuous-wave pump source.

Main Methods:

• Construction of a random fiber laser utilizing SBS for gain and Rayleigh scattering for distributed feedback.
• Integration of a high-finesse, narrow-band Fabry-Perot interferometer (FPI) for frequency selection.
• Characterization of laser output, including directionality, linewidth, frequency jitter, and frequency noise.

Main Results:

• Achieved high-quality coherent random lasing in the weak scattering regime with a milliwatt pump source.
• Demonstrated significant enhancement in random lasing directionality due to light confinement in single-mode fiber.
• Observed relative frequency fluctuation of ~2.5 × 10(-11) at 100 s, frequency jitter within ±20 kHz over 3 hours, a 3 dB linewidth of ~50 Hz, and frequency noise of ~20 mHz/Hz(1/2) at 10 kHz.

Conclusions:

• The developed coherent random fiber laser exhibits excellent frequency stability and narrow linewidth.
• The FPI effectively locks the lasing frequency to a transmission peak, enabling precise frequency control.
• This laser architecture provides a pathway towards high-performance, low-power coherent random fiber lasers.