Enhanced and Stable Upconverted White-light Emission in Ho3+/Yb3+/Tm3+-doped LiNbO3 Single Crystal via Mg2+ Ion Doping

Abstract

A strategy to enhance the upconversion white-light intensity via Mg2+ ion doping was demonstrated in Ho3+/Yb3+/Tm3+/LiNbO3 single crystal. It is found Mg2+ ion doping affects the crystal field symmetry around RE3+ ions and enhance the upconversion emission intensity. Bright white-light is obtained when the Mg2+ ion concentration is 0.5 mol% in the melt. And the CIE coordinates are hardly changed with Mg2+ ion doping. In addition, the upconversion mechanism is discussed in detail. It is observed the longer lifetimes of intermediate levels result in the lower upconversion photon numbers, which are beneficial to the upconversion process. Therefore, Mg2+ ion doped Ho3+/Yb3+/Tm3+/LiNbO3 single crystals would have potential applications in stable white-light devices and photoelectric instruments.

Effect of Hf 4+ doping on structure and enhancement of upconversion luminescence in Yb:Tm:LiNbO 3 crystals

“…While, as a sensitizer, Yb 3+ ion can strongly absorb the pumping light and transfer energy to Tm 3+ ions, which increases the pumping light absorption efficiency and lowers the laser threshold. [10,12] The upconversion luminescence of Yb 3+ and Tm 3+ codoped LiNbO 3 crystals has been reported by Xing et al [13] As we all know, the application of Yb:Tm:LiNbO 3 crystal in frequency doubler and laser medium material is limited by the photorefractive damage and the problem can be overcome by doping anti-photorefractive ions such as Mg 2+ , Zn 2+ , Sc 3+ , In 3+ , Hf 4+ , and Zr 4+ ions. [14][15][16][17][18][19] It is worthy of notice that luminescence behavior can be improved by doping anti-photorefractive ions.…”

Remarkably enhanced upconversion luminescence in Na+ codoped spinel nanoparticles for photothermal cancer therapy and SPECT imaging

“…The desired UCL intensity enhancement, controllable emission, chromaticity, and high color purity required for emerging applications could not be achieved by merely codoping Yb 3+ ions as higher concentrations of RE 3+ are detrimental to UCL. 30 Therefore, researchers have focussed on crystal field modulation, which is an effective way to improve upconversion emission intensity essential for practical applications. 31 The same could be achieved by codoping of non-luminous centres that play the role of local field modifiers and surface enhancers, leading to the successful increment in photoluminescence intensity.…”

“…In recent years, many publications showcased the role of alkali ion (Li + , Na + , and K + ) and Mg 2+ codoping in boosting the UCL and DC emission, in order to achieve tunable emission. [30][31][32][33][34][35] In the last decade, some publications have revealed the role of alkali metals in improving both UC and DC emission intensity, with majority of them focussing on Li + ion co-doping in different Ho 3+ activated host matrices. 33,36 The effect of Na + codoping has been also explored in phosphors, thereby enhancing emission efficiency 32,34,35,37,38 but there are very few reports in the literature that emphasize the effect of Na + codoping in Ho 3+ /Yb 3+ doped materials.…”