Abstract:

LiYF₄ crystal is a laser host material with excellent optical and physical properties, and Tb³⁺ doping endows it with great potential for high-energy pulsed laser operation in the green and yellow spectral regions. However, the hygroscopicity of fluoride raw materials, the volatility of components at high temperatures, and the strong corrosiveness pose challenges to the growth of high-quality crystals and cost control. In this work, a Tb:LiYF₄ single crystal with dimensions of φ16 mm×120 mm was successfully grown using a vacuum-sealed platinum crucible combined with the vertical Bridgman method. The crystalline quality, compositional uniformity, and optical properties were systematically characterized using multiple techniques. The crystal exhibits a transmittance exceeding 93% and an absorption coefficient below 0.02 cm^-1 in the transparent region, indicating excellent optical quality. Based on Judd-Ofelt theory, three intensity parameters and related spectroscopic parameters were obtained, and temperature dependent fluorescence emission spectra and fluorescence decay curves were measured. Strong emissions were observed at 545 and 585 nm, with fluorescence branching ratios of 57% and 15%, respectively. The fluorescence lifetime of the ⁵D₄ level at room temperature is 4.83 ms. The relatively large branching ratios and the long fluorescence lifetime indicate that Tb:LiYF₄ crystal has great potential for achieving efficient laser output in the green and yellow spectral regions. This work establishes a feasible growth method for Tb:LiYF₄ crystals and provides a systematic investigation of their spectroscopic properties, providing a material basis and experimental support for the development of high-efficiency green and yellow solid-state lasers.

Key words: Bridgman method, sealed crucible, Tb:LiYF₄ crystal, Judd-Ofelt theory, spectroscopic property