Rare Earth Ion (Er, Yb, Nd, Ce) Doped RePO₄ (Re=Y, Lu) Crystal Growth, Spectrum And Laser Performance Research

Rare earth orthophosphate crystal can be used as laser host material for diode-pumped solid-state lasers due to the excellent radiation resistance,good chemical stability and high melting temperature.Concentration quenching will not happen with high concentration doping of active ions.But,owing to the high difficulties of crystal growth,the quality and size of rare earth orthophosphate crystal restrict its application in Laser.To solve these problems,in this work,we selected appropriate flux system and report the growth,spectroscopic and laser properties of RePO₄（Re=Y,Lu）crystals with special doping concentration of rare-earth ions（Er,Yb,Nd,Ce）for the first time to the best of our knowledge.The polarization absorption cross sections and the full width of half maximum of the Er:Yb:Lu PO₄ were recorded.The up-conversion luminescence spectra and near-infrared luminescence spectra of both Er:Yb:LuPO₄ and Er:Yb:Ce:LuPO₄ crystals were recorded by Fluorolog-3 fluorescence spectrometer under 980 nm pumping.The results indicate that with high concentration co-doping of Ce³⁺ions,the up-conversion energy losses are remarkably reduced in Er:Yb:Ce:LuPO₄ crystal.Consequently,the luminescence intensity in the waveband of 1.5¹.6μm of Er:Yb:Ce:LuPO₄ is increased by two times compared to Er:Yb:LuPO₄.The un-polarized absorption cross section of 3at%Nd:YPO₄ crystal was measured.A fiber-coupled laser diode was used as the pump source.2.16 W and 0.8 W of continue wave output power around 1.06μm and 1.34μm were generated under 805 nm pumping.For 7.5at%Yb:LuPO₄ crystal,the un-polarized absorption cross section in the waveband of 900-1050 nm was recorded.3.14 W of continue wave output power were generated under a fiber-coupled laser diode as the pump source.The output power value of 7.5at%:LuPO₄ is almost two times compared to 5at%:LuPO₄（1.61 W）.Our results proved that the doping concentration of Yb ions in LuPO₄ crystal can be further optimized.