UV-laser-diode-pumped visible Tb^3+:LiLuF₄ lasers

Area of Science:

• Solid-state laser physics
• Materials science
• Photonics

Background:

• Terbium-doped LiLuF3 (Tb³⁺:LLF) crystals are promising for visible laser applications.
• Ultraviolet (UV) pumping offers efficient excitation pathways for rare-earth ions.
• Excited-state absorption (ESA) can negatively impact laser performance and induce thermal effects.

Purpose of the Study:

• To investigate the impact of UV pumping wavelength on the visible laser performance of Tb³⁺:LLF.
• To achieve the first UV-laser-diode-pumped Tb³⁺-based laser operation.
• To understand and mitigate thermal effects associated with UV pumping.

Main Methods:

• Experimental investigation of Tb³⁺:LLF laser performance under various UV pumping wavelengths.
• Utilized a UV laser diode emitting at 378.5 nm for continuous wave (CW) laser operation.
• Analyzed the dependence of laser efficiency and threshold on pump wavelength and ESA.

Main Results:

• Identified that strong ESA at certain UV pump wavelengths induces thermal effects, hindering laser performance.
• Demonstrated CW laser operation of a Tb³⁺:LLF laser pumped by a 378.5 nm UV laser diode.
• Achieved slope efficiencies of 36% at 542/544 nm and 17% at 587 nm, with a low threshold of 4 mW.

Conclusions:

• UV pump wavelength selection is critical for optimizing Tb³⁺:LLF visible laser performance by avoiding strong ESA.
• UV laser diode pumping is a viable and efficient method for Tb³⁺-based lasers.
• The developed Tb³⁺:LLF laser shows high efficiency and low threshold, suitable for various applications.