Raman spectra and laser properties of Yb-doped yttrium orthovanadate crystals

Yb-doped yttrium orthovanadate YbxY1-xVO4 (YYV), with x=0.02, crystallizes with a zircon-type structure in the tetragonal system, conforming to the sp ace group I4(1)/amd. The lattice constants are a=0.7122(5) and c=0.6291(3) nm at room temperature. The primitive cell contains four formula units. The Raman spectra and crystallography show no distortion of the VO4 and Y/YbO8 groups. The crystal field is similar to that of the YVO4 crystal and is su itable for the dopant Yb3+ ions. A strong absorption at 975 nm arises from the F-2(7/2) to F-2(5/2) transition; with a bandwidth of 70 nm it may provi de a useful pump band for InGaAs diode lasers. This band is about seven tim es broader than that of Nd-doped yttrium aluminum garnet and more than thre e times as broad as that of Nd-doped yttrium orthovanadate. The measured ab sorption of the YYV is compared to Judd-Ofelt (JO) theory. When applied, th e JO theory of parity-forbidden electric-dipole transitions of rare earth i ons on noncentrosymmetric sites demonstrates good agreement. The fluorescen ce spectrum reveals a ground state splitting of Delta E=463 cm(-1). The fit ted fluorescence lifetime is 1.18 ms at the wavelength of 1.0 mu m. The cal culated absorption cross section is 1.38x10(-20) cm(2). The order of magnit ude of the emission cross section is estimated as 10(-21) cm(2). In Yb-dope d yttrium aluminum garnet, the fluorescence lifetime is about 1.16-1.30 ms and the absorption cross section is 1.5x10(-20) cm(2). In Nd-doped yttrium orthovanadate, the fluorescence lifetime is 115 mu s and the emission cross section is 10.7x10(-19) cm(2). A suitable concentration of the Yb3+ ions d oped in the YbxY1-xVO4 crystals should modify the optical and the potential laser properties of the crystals. (C) 2000 American Institute of Physics. [S0021-8979(00)06401-X].