High power downconversion deep-red emission from Ho³⁺-doped fiber lasers.

Area of Science:

• Laser Physics
• Materials Science

Background:

• Holmium (Ho³⁺)-doped fiber lasers face challenges in achieving high deep-red emission power due to long carrier lifetimes.
• Existing methods struggle to overcome the intrinsic limitations of Ho³⁺ energy levels for efficient deep-red lasing.

Purpose of the Study:

• To develop a novel pumping strategy for Ho³⁺-doped fiber lasers to achieve high output power in the deep-red spectrum.
• To overcome the long carrier lifetime issue in the ⁵I₇ energy level of Ho³⁺.

Main Methods:

• Utilized a novel downconversion pumping mechanism leveraging blue laser diode advantages.
• Employed excited state absorption to shorten the lower laser level lifetime.
• Demonstrated a downconversion fiber laser using a 532 nm solid-state laser pump source on Ho³⁺-doped ZBLAN fiber.

Main Results:

• Achieved a record maximum output power of 1.64 W at 752.10 nm.
• Successfully demonstrated free-running deep-red lasers with watt-level output.
• Established a new milestone in high-power deep-red fiber laser development.

Conclusions:

• The novel pumping method effectively overcomes Ho³⁺ limitations for deep-red lasing.
• This technology represents a significant advancement for high-power deep-red fiber lasers.
• The approach is extendable to other wavelengths, indicating broad application potential in the fiber laser industry.