Highly efficient temporally stable narrow linewidth cryogenically cooled Yb-fiber laser

Area of Science:

• Laser physics
• Optical engineering
• Materials science

Background:

• Cryogenic cooling boosts solid-state laser efficiency.
• Fiber lasers face linewidth broadening and reduced spectral power density when cryogenically cooled due to decreased reabsorption and homogeneous broadening.
• This limits their application in high-resolution spectroscopy and coherent systems.

Purpose of the Study:

• To achieve a temporally stable, narrow linewidth, and highly efficient laser output from a cryogenically-cooled Yb-doped fiber laser.
• To overcome the linewidth broadening issue associated with cryogenic cooling in fiber lasers.
• To demonstrate the effectiveness of volume Bragg gratings in spectral control for cryogenically-cooled fiber lasers.

Main Methods:

• Utilized a cryogenically-cooled Ytterbium (Yb)-doped fiber laser.
• Integrated a volume Bragg grating (VBG) for spectral locking and linewidth narrowing.
• Characterized laser output power and spectral characteristics under cryogenic conditions.

Main Results:

• Achieved a stable narrow linewidth output of less than 0.4-nm.
• Extracted 11.4-W of output power.
• Demonstrated high efficiency with 14.5-W of launched pump light.

Conclusions:

• Cryogenic cooling combined with VBG spectral locking effectively suppresses linewidth broadening in Yb-doped fiber lasers.
• This approach yields a highly efficient, temporally stable, narrow-linewidth laser source.
• The results indicate significant potential for applications requiring high spectral power density.