Bidirectional pumped high power Raman fiber laser

Area of Science:

• Optics and Photonics
• Fiber Lasers
• Nonlinear Optics

Background:

• High-power fiber lasers are crucial for various industrial and scientific applications.
• Achieving high efficiency and specific wavelengths in fiber lasers often requires complex multi-stage systems.
• Developing cost-effective and efficient pumping schemes for fiber lasers remains an active research area.

Purpose of the Study:

• To present a novel 1123 nm Raman all-fiber laser system.
• To investigate the efficacy of bidirectional pumping using non-wavelength-stabilized laser diodes (LDs) in a Ytterbium-doped fiber amplifier.
• To achieve high optical-to-optical efficiency and a specific output wavelength without higher-order Raman effects.

Main Methods:

• Utilized a single-wavelength (1070 nm) seed laser.
• Employed a one-stage bidirectional pumping configuration with 976 nm non-wavelength-stabilized laser diodes (LDs).
• Integrated refractive index valley fiber combiners for efficient pump power delivery and amplification.
• Conducted theoretical analysis and experimental validation of the Ytterbium (Yb3+) ion energy transfer and first-order Raman conversion.

Main Results:

• Achieved a 3.89 kW output power for the 1123 nm Raman all-fiber laser.
• Demonstrated an overall optical-to-optical efficiency of 70.9%.
• Successfully converted 976 nm pump light to 1070 nm via Yb3+ transfer and subsequently to 1123 nm via first-order Raman scattering.
• Confirmed the absence of any higher-order Raman laser generation.

Conclusions:

• The bidirectional pumping configuration with non-wavelength-stabilized LDs is an effective method for high-power fiber laser generation.
• This approach simplifies the amplifier design by avoiding multi-stage configurations and reducing fiber length.
• The demonstrated system offers a promising pathway for efficient generation of specific wavelength Raman fiber lasers.