Low threshold, high-power Tm/Ho co-doped double-clad single-mode silica fiber operation at 2.08 μm

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Physics

Background:

• 2.0 µm fiber lasers are crucial for medical applications.
• Thulium (Tm) and Holmium (Ho) co-doping is a promising strategy for achieving efficient 2.0 µm laser emission.
• Optimizing energy transfer between Tm and Ho ions is key to maximizing laser performance.

Purpose of the Study:

• To develop a Tm/Ho co-doped double-clad single-mode silica fiber laser.
• To investigate the energy transfer efficiency between Tm and Ho ions.
• To evaluate the laser performance, including efficiency, output power, beam quality, and stability.

Main Methods:

• Fabrication of Tm/Ho co-doped silica fiber using chelate-assisted modified chemical vapor deposition (MCVD).
• Characterization of cladding absorption and saturated gain coefficient.
• Measurement of fluorescence lifetime for Tm and Ho ions.
• Analysis of energy transfer efficiency.
• Performance testing of the fiber laser under 793 nm cladding pumping.

Main Results:

• Achieved a cladding absorption of 2.36 dB/m@793 nm and a saturated gain coefficient of 8.0 dB/m.
• Demonstrated a high energy transfer efficiency of approximately 56.35% from Tm (³F₄) to Ho (⁵I₇).
• Obtained a slope efficiency of 46.84% and an output power of 38.9 W at 2080 nm.
• Reported excellent beam quality (M-squared < 1.19), narrow 3 dB bandwidth (0.45 nm), low threshold (3.0 W), and low output power fluctuation (0.21%).

Conclusions:

• The developed Tm/Ho co-doped fiber laser exhibits high performance and stability.
• The efficient energy transfer mechanism is crucial for the laser's capabilities.
• This fiber laser is suitable for advanced applications in medical systems, radar, and remote sensing.