Violet and visible up-conversion emission in Yb3+-Ho3+ co-doped germanium-borate glasses

The up-conversion emission properties of Yb3+-Ho3+ co-doped germanium-borate glasses have been investigated with 980 nm excitation. The violet, blue, green and red emission bands at about 350, 485, 544 and 653 nm can be identified, respectively. Experimental results indicated that the relative intensity ratios of the peaks IRed/IGreen increased with increasing B2O3 concentration, which led to changing color of up-conversion emission from green at x=0 to yellow at x=40, to red at x=60. The violet emission at 350 nm was first reported in germanium-borate glass host and up-conversion mechanisms of the emissions were discussed. The Yb3+-Ho3+ co-doped germanium-borate glasses could be an alternative for the generation of violet and primary colors for application in solid-state displays.