Bulk crystal growth and mechanical and spectroscopic features comparison of Dy3+-doped (LuxY1-x)3Al5O12（x = 0, 1/3, 1/2, 2/3）single crystals for yellow lasers

Abstract A series of high-quality Dy3+-doped (LuxY1-x)3Al5O12 (x = 0, 1/3, 1/2, 2/3, abbr. as Dy3+: LuYAG) crystals have been grown by the Czochralski method, namely Dy3+: Y3Al5O12, Dy3+: LuY2Al5O12, Dy3+: Lu1.5Y1.5Al5O12, and Dy3+: Lu2YAl5O12 crystals with similar Dy3+ concentration of 4 at%. Such crystals were investigated and compared through the measurements of their mechanical and spectral characteristics like absorption, emission spectra, and fluorescence decay times. The crystal crack and inclusion problems were discussed and various precautions were taken to improve the crystalline quality. In all Dy3+: LuYAG crystals, absorption cross-section of each absorption band increases with an increment of Lu3+ content, and the strong absorption with a peak at 447 nm makes Dy3+: LuYAG as highly effective to be pumped by blue-emitting LDs (laser diodes). Under 447 nm excitation, strong yellow emissions (582 nm) were obtained, and in four samples Dy3+: Lu1.5Y1.5Al5O12 crystal shows an intense intensity in the yellow region. Decay times of Dy3+: 4F9/2 level increases with an increment of Lu3+ content. Comparison of mechanical and spectroscopic features revealed that the best candidate for achieving yellow lasing action was Dy3+: Lu1.5Y1.5Al5O12 crystal.