Structure And Physical Properties Study Of Nd: LuVO₄ Laser Crystal

Therere many kinds of lasers, among these lasers, solid-state laser is small and solidity, It's radiate power is strong, so it is used in many fields.The laser diode pump solid-state lasers (DPSSL) possess the merits of both semiconductor and solid. DPSSL has the properties of high pumping efficiency, stable output power and all solid state.Furthermore it is a revolution to traditional lamp pump solid-state lasers. DPSSL have found many important application fields e.g. in material processing, control and guide,medicine, optical communications, lasers display and laser nuclear fusion.So far as DPSSL is concerned, laser materials are important and they are the keyfactor for designing all solid-state lasers for DPSSL and determine the properties of lasers. Laser materials were studied far and widely. Laser crystal is the work material for DPSSL. The solid-state laser crystal's study begin in sixties, in the last forty years,the laser crystals was developed,.the number of the laser crystals increased from several to more than one hundred. As the main part of the solid -state lasers, laser rcrystals became the most important work material. Among lots of laser crystals, rare earth orthovanadates with ZrSiO₄ structure is a kind of excellent laser material,especially Nd doped orthovanadates, such as Nd: YVO₄, Nd: GdVO₄,,Nd: Gd_xLa_1-xVO₄and Nd: Y_xLa_1-xVO₄ and so on.Nd: LuVO₄ crystal is a orthovanadates with ZrSiO₄ structure. It was grown by themethod of Czochralski in 1996. C.Maunier grew Nd: LuVO₄ by using the flux technique in 2002. With the spectral and laser performance, Nd: LuVO₄ crystal should be an excellent laser crystal. C.Maunier perform the laser output at 1066nm(pumped by a cw Ti: sapphire laser, output power of 80mW and slope eficiency of 60-66% were obtained, and the pumped threshold was about 30mW).Recently, in National Laboratory of Crystal Materials of Shandong University, Huaijin Zhang grew Nd: LuVO₄ crystal by Czochralski method, when it was pumped by a fiber-coupled cw laser-coupled cw laser-diode array, the output power of Nd : LuVO₄ crystal at 1064nm was 530mW(pumping power is 2.76 W), the slope eficiency is 23.1%, and the optical-optical conversion eficiency is 19.3%. although the conversion efficiency is not high enough, this is the first time the output power reach 530 mW. So it is mean that the laser performance of Nd: LuVO₄ crystal is excellent, and should be a good laser material. But now the research of Nd: LUVO₄ crystal is just begin, the performance should be studied more.Then this article perform the research of Nd: LUVO₄ crystal, and has done some work below:To determine the structure of Nd: LuVO₄ crystal, we measured the Raman spectrum of crystal at room temperature on JascoVentuno²¹ Raman Micro spectrophotometer, and point out the Raman shift. Analyzed the space structure of Nd: LUVO₄ crystal, use the factor symmetry analysis method, we can obtain the reducible representations for the space group I4₁/amd at the center ? point of the first Brillouin zone. From the reducible representations, we can know that the number of Raman shift should be no more than 32, and this is well accord with the experimental result.Measured the Infrared spectrum of Nd: LUVO₄ crystal. Based on the reducible representations, we can know the number of Infrared bands is no more than 13, and because the crystal has symmetrical center, so the Infrared spectrum and the Raman spectrum should have no same bands. this is also well accord with the experimental resultMeasured the absorption and fluorescence spectrum of Nd:LuVO₄ crystal at room temperature. From the spectrum, the main absorption bands is recorded as 808nm, and the main emission bands is recorded as 1065nm. Use the J-0 theory, the absorption and the emission cross section was calculated.For the laser crystal, the thermal parameters is important. So we measured the thermal expansion efficient, thermal difusivity and specific heat of Nd: LUVO₄ crystal,and then calculated the thermal conductivity.