PLD-grown Yb-doped Sesquioxide Films on Sapphire and Quartz Substrates

Abstract

This paper focuses on the fabrication and characterization of crystalline Yb-doped sesquioxide films (Yb2O3, Yb:Lu2O3, Yb:Sc2O3) grown by pulsed laser deposition on single crystal sapphire (α-Al2O3) and quartz (α-SiO2) substrates as well as on lutetia (Lu2O3) and scandia (Sc2O3) substrates. Such ytterbium doped active films can be promising for use in a thin-disk laser setup. X-Ray diffraction measurements show that the films grow highly textured along <111> direction. The ω-scan (rocking curve) shows deviation of the crystallite orientation ∼4° in case of Lu2O3 and Yb2O3 films and <1° for Sc2O3 films. Yb2O3 films reveal no luminescence at room temperature and the well known Yb3+ emission in the 975-980 nm region (zero-phonon line) can only be observed at temperatures below 20 K. A similar effect is observed in a bulk Yb2O3 crystal. Ytterbium emission and excitation spectra measured at room temperature for Yb(5%):Lu2O3 and Yb(4%):Sc2O3 films resemble those of the bulk crystal very closely. Luminescence decay lifetimes are also comparable to those measured in a bulk crystal. This indicates a high quantum efficiency of the Yb3+-emission and allows application of such films as active media for thin disk lasers.