Optical properties of LiNbO3 crystals doubly doped with Nd3+ and Yb3+ ions

The LiNbO3 crystals doubly doped with Nd3+ and Yb3+ ions grown by the Czoch ralski method were investigated. The positions of the F-4(3/2) level of Nd3 + and of the ground F-2(7/2) and excited F-2(5/2) levels of Yb3+ are determ ined. The splittings observed in the low temperature emission spectra evide nce that both Nd3+ and Yb3+ occupy more than one site in the crystal host. The excitation into Nd3+ absorption bands brings about the emission of both Nd3+ and Yb3+ ions which covers a near infrared range from 850 to 1120 nm. The emission cross section and gain curves for some values of inversion pa rameters are presented for Yb3+ ions.