Monochromatic NIR UC emission in Tm3+/Yb3+ co-doped GdVO4 phosphor: The effect of the Bi3+ ion concentration and pump power of a diode laser

Abstract

A Tm3∕Yb3∕Bi3 co-doped GdVO4 phosphor sample has been synthesized using a high-temperature solid-state reaction technique. The X-ray diffraction patterns reveal pure phase formation and crystalline behavior of the synthesized samples. Intense blue and NIR upconversion emissions have been observed upon excitation with a 980 nm diode laser. It is found that the addition of the Bi3 ion to the phosphor reduces the intensity of blue emission and enhances the NIR emission intensity to the extent that NIR emission is nearly monochromatic [I NIR∕IBlue ∼ 14]. This ratio is further improved up to 70 times (almost monochromatic) by varying the pump power of the diode laser. Thus, this material can be used as a cheap source of monochromatic NIR emission at 800 nm for bioimaging. © 2018 Optical Society of America