Highly efficient ytterbium-doped phosphosilicate fiber lasers operating below 1020 nm

Area of Science:

• Laser Physics
• Materials Science

Background:

• High-power fiber lasers require efficient pump sources below 1020 nm for optimal performance.
• Existing pump sources face limitations in brightness and thermal management.

Purpose of the Study:

• To develop a highly efficient fiber laser operating below 1020 nm.
• To investigate the potential of ytterbium-doped phosphosilicate leakage-channel fibers for high-power laser applications.

Main Methods:

• Fabrication and characterization of a ~50 µm core / ~420 µm cladding ytterbium-doped phosphosilicate double-clad leakage-channel fiber.
• Experimental demonstration of laser operation at 1018 nm.
• Systematic study of efficiency-limiting factors.

Main Results:

• Achieved ~70% optical-to-optical efficiency at 1018 nm.
• Demonstrated high Amplified Spontaneous Emission (ASE) suppression of ~41 dB.
• The larger cladding diameter allows for lower pump brightness requirements, crucial for kW-level operation.

Conclusions:

• The developed fiber laser design offers a promising solution for efficient pumping in high-power fiber laser systems.
• The unique fiber properties facilitate lower pump brightness, enabling efficient kW operation.
• Further studies will focus on optimizing efficiency and exploring applications.