Efficient high power, narrow linewidth 1.9  μm fiber hydrogen Raman amplifier

Area of Science:

• Fiber optics
• Nonlinear optics
• Laser physics

Background:

• Gas Raman lasers offer unique wavelength generation capabilities.
• Hollow-core fibers provide a robust platform for gas-based nonlinear optics.
• Achieving high power and narrow linewidth simultaneously is a key challenge.

Purpose of the Study:

• To demonstrate an efficient, high-power, narrow-linewidth 1.9 μm gas Raman amplifier.
• To investigate the performance of stimulated Raman scattering in hydrogen-filled hollow-core fibers.
• To explore the potential for cascaded Raman scattering to generate mid-infrared wavelengths.

Main Methods:

• Utilized a hydrogen-filled hollow-core fiber as the gain medium.
• Coupled a 1.9 μm continuous wave seed laser and a 1064 nm MOPA laser into the fiber.
• Employed stimulated Raman scattering (SRS) in hydrogen for amplification.

Main Results:

• Achieved a maximum average Stokes power of 570 mW at 1908 nm, a record for this type of experiment.
• Obtained a maximum peak power of approximately 50 kW with a linewidth of about 1 GHz.
• Demonstrated a quantum efficiency of approximately 51%.

Conclusions:

• Successfully demonstrated a high-power, narrow-linewidth gas Raman amplifier in a hollow-core fiber.
• The results highlight the potential of this approach for generating high-power fiber lasers.
• This work paves the way for developing high-average-power 4 μm mid-infrared fiber lasers via cascaded SRS.