Upconversion emission from amorphous Y2O3:Tm3+, Yb3+ prepared by nanosecond pulsed laser irradiation

Y2O3:Tm3+, Yb3+ was prepared by nanosecond pulsed laser irradiation. The X-ray diffraction pattern shows that the material produced by laser irradiation is amorphous, which presents strong blue upconversion emission under the excitation of 976 nm diode laser. The relative intensity of the blue emission to the infrared one is linearly dependent on the pump power and is an order of magnitude higher than that of the bulk material. The analyses of rate equations and the time-resolved spectroscopic results indicate that the enhancement of the blue upconversion is attributed to the longer lifetime of the levels of the Tm3+ and Yb3+ ions.