Influence of Tm3+ ions on the amplification of Ho3+:5I7→5I8 transition in fluoride glass modified by Al(PO3)3 for applications in mid-infrared optics

In this work, we investigate a new type of fluoride glasses modified by Al(PO3)(3) with various Tm3+/Ho3+ doping concentrations. The introduced PO3- plays an effective role in improving the glass-forming ability and thermal stability. Besides, 1.47, 1.8, and 2.0 mu m emissions originating from Tm3+ and Ho3+, respectively, are observed. The spectroscopic properties and energy transfer mechanisms between Tm3+ and Ho3+ are analyzed as well. It is noted that the higher predicted spontaneous transition probability (118.74 s(-1)) along with the larger product of measured decay lifetime and the emission cross section (sigma(emi) x tau) give evidence of intense 2.0 mu m fluorescence.