Efficient Tm-doped silica fiber laser incorporating nanoparticle doping

Area of Science:

• Materials Science
• Optics and Photonics
• Laser Physics

Background:

• Standard solution doping methods limit thulium (Tm) ion concentrations in fiber lasers.
• High doping levels are crucial for efficient laser operation, particularly for processes like cross-relaxation.

Purpose of the Study:

• To report the efficient operation of a novel Tm-doped aluminosilicate fiber laser.
• To investigate the impact of nanoparticle doping for achieving high Tm concentrations.
• To evaluate laser performance metrics including slope efficiency and quantum efficiency.

Main Methods:

• Fabrication of Tm-doped aluminosilicate fibers using nanoparticle doping with varying Tm concentrations (20 mol.% and 100 mol.%).
• Diode-pumping of the fabricated fiber lasers.
• Characterization of laser performance, including slope efficiency, quantum efficiency, and core propagation loss.

Main Results:

• Achieved moderately high slope efficiencies exceeding 50%.
• Observed quantum efficiencies of 1.35 and 1.53 for the 20 mol.% and 100 mol.% Tm:NP fibers, respectively.
• Measured core propagation losses of 0.14 dB/m and 0.42 dB/m, which scaled with average Tm concentration.

Conclusions:

• Nanoparticle doping is an effective method for realizing high localized Tm-doping concentrations in fiber lasers.
• The 'two-for-one' cross-relaxation process is likely being exploited, leading to efficient laser operation.
• Further investigation is needed to quantify the impact of energy transfer upconversion on laser performance.