Comparative Performance Analysis of Femtosecond-Laser-Written Diode-Pumped Pr:LiLuF4 Visible Waveguide Lasers

In this work, we present the operation of a femtosecond-laser-written diode-pumped visible waveguide laser based on praseodymium-doped lithium lutetium fluoride. The refractive index modification induced by the femtosecond laser in the crystal exhibits an anisotropic behavior, thus enabling the fabrication of different types of waveguides from single-track structures to stress-induced waveguides and depressed cladding structures. All the waveguides were characterized by realizing transmission measurements and the waveguide design was optimized to obtain extremely low propagation losses, equal to 0.12 dB/cm. Lasing has been achieved at 604 nm and 721 nm from different waveguides. In addition, stable continuous-wave lasing at 698 nm has been obtained in a depressed cladding waveguide. This wavelength corresponds to the one needed for the transition of the atomic clock based on the neutral strontium atom. In the end, we report the observation of laser emission at 645 nm from a depressed cladding waveguide.

Automated summary

This work presents the operation of a femtosecond-laser-written diode-pumped visible waveguide laser based on praseodymium-doped lithium lutetium fluoride. Different types of waveguides, including single-track structures, stress-induced waveguides, and depressed cladding structures, were fabricated using the femtosecond laser-induced refractive index modification in the crystal. The waveguide design was optimized to achieve extremely low propagation losses, and lasing at various wavelengths, including 604 nm, 721 nm, and 698 nm, was achieved from different waveguides.