2-W continuous-wave and passively Q-switched Tm,Ho:YLF channeled waveguide laser at 2.05 µm

Area of Science:

• Laser Physics
• Materials Science

Background:

• Waveguide lasers offer compact and efficient laser sources.
• Thulium and holmium co-doped materials are suitable for mid-infrared emission.

Purpose of the Study:

• To investigate the performance of a Tm,Ho:YLF depressed cladding waveguide laser.
• To evaluate its capabilities in both continuous-wave (CW) and passively Q-switched (PQS) regimes.

Main Methods:

• Fabrication of a 70-µm diameter depressed cladding waveguide using femtosecond laser inscription.
• Characterization of propagation loss and refractive index contrast.
• Testing CW operation with 780 nm excitation.
• Implementing PQS operation using a Cr:ZnSe saturable absorber.

Main Results:

• Achieved low propagation loss (0.14 dB/cm) and a refractive index contrast of 8.3 × 10⁻⁴.
• Generated up to 2 W output power in CW mode with 50.0% power slope efficiency.
• Produced 19.6-ns pulses in PQS mode with 18.9% power slope efficiency.

Conclusions:

• The Tm,Ho:YLF depressed cladding waveguide laser is an efficient source for 2.05 µm emission.
• The device demonstrates versatile operation in both CW and PQS regimes.
• Femtosecond laser inscribed waveguides provide a robust platform for high-performance laser development.