Fs-laser-written erbium-doped double tungstate waveguide laser

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Physics

Background:

• Waveguide lasers offer miniaturization and high efficiency for various applications.
• Erbium-doped materials are crucial for telecommunication wavelengths.
• Double tungstate crystals are promising gain media for solid-state lasers.

Purpose of the Study:

• To report the first erbium-doped double tungstate waveguide laser.
• To investigate the performance of Er³⁺:KLu(WO₄)₂ as a gain material in a waveguide format.
• To demonstrate diode-pumped laser operation at telecommunication wavelengths.

Main Methods:

• Fabrication of a depressed-index buried channel waveguide using 3D femtosecond direct laser writing.
• Characterization of the waveguide using confocal laser microscopy, µ-Raman, and µ-luminescence mapping.
• Diode-pumped continuous-wave (CW) laser operation at 981 nm.

Main Results:

• Preservation of core crystallinity confirmed through material characterization.
• Laser output of 8.9 mW at 1533.6 nm achieved.
• Slope efficiency of 20.9% and a laser threshold of 93 mW absorbed pump power recorded.
• Linear polarization (E || N_m) of the laser output observed.

Conclusions:

• Successful demonstration of the first erbium-doped double tungstate waveguide laser.
• Er³⁺:KLu(WO₄)₂ is a viable gain material for waveguide laser applications.
• The fabricated waveguide laser operates efficiently at 1533.6 nm.