Single-frequency low-threshold linearly polarized DFB Raman fiber lasers

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Distributed feedback (DFB) fiber lasers are known for narrow linewidths but are typically limited to rare-earth-doped fibers.
• Raman gain provides a versatile alternative, enabling laser operation at arbitrary wavelengths.

Purpose of the Study:

• To demonstrate linearly polarized, single-frequency, DFB fiber Bragg grating Raman lasers.
• To achieve low pump thresholds and characterize laser performance, including output power and efficiency.
• To investigate the role of stimulated Brillouin scattering in high-power operation and characterize internal power profiles.

Main Methods:

• Fabrication of DFB fiber Bragg grating structures.
• Utilizing Raman gain for laser operation.
• Employing a novel side-scatter technique for internal power profile characterization.

Main Results:

• Achieved the lowest reported pump threshold of 350 mW for DFB fiber Bragg grating Raman lasers.
• Demonstrated output power up to 50 mW at 1120 nm with an 8.5% slope efficiency.
• Obtained 300 mW of output power at 1178 nm, with stimulated Brillouin scattering influencing high-power dynamics.

Conclusions:

• DFB fiber Bragg grating Raman lasers are viable alternatives to rare-earth-doped fiber lasers.
• The demonstrated low threshold and high output power highlight the potential of these lasers.
• The characterization of power profiles provides valuable insights for further laser development.