Efficient and low-threshold Cr4+:YAG double-clad crystal fiber laser

Area of Science:

• Materials Science
• Laser Physics
• Solid-State Photonics

Background:

• Cr4+:Y3Al5O12 (Cr4+:YAG) is a promising material for solid-state lasers.
• Previous Cr4+:YAG lasers, in bulk or fiber forms, faced limitations in efficiency and threshold.
• Developing high-performance Cr4+:YAG lasers is crucial for various optical applications.

Purpose of the Study:

• To demonstrate continuous-wave (cw) lasing in Cr4+:YAG double-clad crystal fiber.
• To achieve record-high optical-to-optical slope efficiency and low lasing threshold.
• To investigate the factors contributing to enhanced laser performance.

Main Methods:

• Growth of Cr4+:YAG double-clad crystal fiber using the codrawing laser-heated pedestal growth technique.
• Characterization of laser performance at room temperature (RT).
• Comparison of experimental results with simulations.

Main Results:

• Demonstrated cw lasing in Cr4+:YAG double-clad crystal fiber at RT.
• Achieved a record optical-to-optical slope efficiency of 33.9%.
• Obtained a low lasing threshold of 78.2 mW, consistent with simulations.
• Identified strain release in Cr4+ tetrahedrons and improved core uniformity as key factors for high efficiency.
• Mitigated photobleaching and reduced excited state absorption of pump light.

Conclusions:

• The codrawing laser-heated pedestal growth technique enables high-efficiency Cr4+:YAG fiber lasers.
• Strain engineering and improved fiber uniformity are critical for overcoming previous limitations.
• This work sets a new benchmark for Cr4+:YAG laser performance.