Abstract

Broadly tunable solid state lasers are required for applications such as LIDAR where multi-wavelength measurements can determine size, shape and distribution of atmospheric aerosols. However, in the important 900–1100 nm range, established reliable and efficient tunable solid state lasers are not currently available Although Ti:sapphire lasers do operate in this range, the gain of Ti³⁺ is comparatively low at these wavelengths. To fill this spectral gap for LIDAR applications, we have developed and evaluated LiF:F₂⁺ room temperature color center lasers pumped by 532 nm radiation. Since 532 nm matches the absorption bands of both F₂ and F₂⁺, the pump light is used to simultaneously create the laser active F₂⁺ centres (by the two-step F₂→F₂→F₂⁺ process) and excite the F₂⁺ centers. Laser operation of LiF(F₂→F₂⁺) lasers has been briefly reported¹,², and there is now a need for a detailed characterization of the performance and limitations of LiF:F₂⁺ in terms of the physics of the LiF(F₂→F₂⁺) system, and a comparison of LiF:F₂⁺ with Ti:sapphire, its competitor for LIDAR applications. Here we show that LiF:F₂⁺ operates with substantially lower thresholds, broader tuning, higher output pulse energies and shorter pulses than Ti:sapphire in the 900–1100 nm spectral region. The principal limitations on LiF:F₂⁺ lasers are identified as ASE and a slow thermal degradation.

© 2000 IEEE