The Study On The Growth And Spectra Of Er:baY₂F₈Crystal

The Er:BaY2F8crystal is an excellent laser crystal material. Compared with otheroptical crystals, Er:BaY2F8crystal has much excellent performance, such as lowerphonon energy, higher transmittance and larger emission cross section. The researchshows that Er:BaY2F8crystal has a large application perspective in the developmentof new laser material. In this paper, we report the growth of Er:BaY2F8crystal bytemperature gradient technique (TGT) method. The cracking phenomenon in thecrystal growth is analyzed. We also have investigated the optical properties ofEr:BaY2F8crystal.The Er:BaY2F8crystal is grown by temperature gradient technique method. Thecracking phenomenon in the crystal growth is observed and analyzed. The factors ofcrystal cracking are discussed, such as the thermal stress, temperature gradient,growth rate and cooling rate. On the basis of experiments and theoretical analyses, theoptimal growth parameters are obtained as follows: the axial gradient temperature is6℃/mm, the growth rate is0.25mm/h and final cooling rate is10℃/h.The absorption spectra, emission spectra and excitation spectra of Er:BaY2F8crystal aremeasured and the optical properties of the crystal are analyzed. We focus on the temperaturedependence of emissons of Er:BaY2F8crystal. Two typical green emissions were observedat about520nm and552nm, which are assigned to2H11/2â†'4I15/2and4S3/2â†'4I15/2transitions respectively. It is observed that the520nm increases while the552nmdecreases with temperature increasing. The results were explained by thenon-radiative relaxation and thermal enhancing at higher temperatures. The emissionat about1.5μm is also discussed considering the Stark Spliting. With temperatureincreasing, the broadening and blue-shift of the1.5μm emission are observed. Thephenomenon due to the temperature dependence of multiphonon relaxation betweenthe4I13/2and4I15/2states and the changing population distribution among the Starklevels within the4I13/2state.