Linearly polarized random fiber laser with ultimate efficiency.

Area of Science:

• Photonics
• Laser Physics
• Materials Science

Background:

• Random fiber lasers offer unique advantages due to distributed feedback.
• Achieving high power and high polarization extinction ratio simultaneously is challenging.
• Previous Raman fiber lasers had limitations in efficiency and output characteristics.

Purpose of the Study:

• To develop a high-power, linearly polarized random fiber laser.
• To investigate the performance of a 500-m polarization-maintaining (PM) fiber laser.
• To achieve record-breaking optical efficiency in a Raman fiber laser.

Main Methods:

• Utilized linearly polarized pumping.
• Employed a 500-m long polarization-maintaining (PM) fiber.
• Incorporated a PM fiber-loop mirror for feedback.
• Operated as a Raman fiber laser with random distributed feedback.

Main Results:

• Generated linearly polarized radiation at 1.11 μm.
• Achieved a polarization extinction ratio (PER) of 25 dB.
• Reached an output power of up to 9.4 W.
• Demonstrated an absolute optical efficiency of 87% for pump-to-Stokes wave conversion.
• Observed output linewidth saturation at 1.8 nm at high powers.

Conclusions:

• The developed random fiber laser demonstrates state-of-the-art performance in terms of power and polarization.
• The achieved 87% optical efficiency is near the quantum limit, setting a new record for this laser type.
• The results pave the way for advanced applications requiring high-power, polarized laser sources.