High-power transverse-mode-switchable all-fiber picosecond MOPA

Area of Science:

• Fiber laser technology
• Nonlinear optics
• Laser engineering

Background:

• Picosecond pulsed lasers are crucial for high-resolution material processing.
• Achieving high power while maintaining beam quality and spectral integrity is challenging.
• All-fiber systems offer advantages in compactness and reliability.

Purpose of the Study:

• To demonstrate a high-power, transverse-mode-switchable all-fiber picosecond laser.
• To investigate the amplification characteristics and nonlinear effects of different fiber modes.
• To assess the suitability of this laser for practical applications.

Main Methods:

• Utilizing a gain-switched laser diode master oscillator.
• Employing multi-stage ytterbium-doped fiber amplification.
• Implementing a mechanical long-period grating for mode conversion (LP01 to LP11).

Main Results:

• Achieved 117 W average output power at 1.06 μm with a 25 MHz repetition rate.
• Demonstrated efficient mode conversion between fundamental (LP01) and second-order (LP11) modes.
• Observed similar optical-to-optical conversion efficiency for both modes.
• Showed significantly alleviated nonlinear spectral degradation in LP11 mode operation.

Conclusions:

• The developed all-fiber laser system is compact, reliable, and capable of high-power operation.
• Mode switching capability, particularly in LP11, enhances spectral stability.
• The laser is promising for applications requiring high precision, such as laser micro-processing.