Infrared-to-visible upconversion in Nd3+-doped chalcohalide glasses

This is the authors' abstract. We don't add key points for this paper.

The infrared to visible upconversion processes have been investigated for Nd³⁺-doped chalcohalide glasses with different halide modifiers by using steady-state and time-resolved laser spectroscopy. Two different upconversion mechanisms have been identified depending on the infrared excitation wavelength. When the excitation wavelength is resonant with the ⁴F3/2 state, three main bands at 538, 600, and 675 nm are observed and attributed to emissions from the ⁴G7/2 level. These upconverted emissions occur via energy-transfer upconversion involving two neodymium ions in the ⁴F3/2 state. However, nonresonant excitation at higher energies than that of ⁴F3/2 state (between states ⁴F3/2 and ⁴F5/2) or in resonance with the ⁴F5/2 state, causes an additional blue emission to originate from the ²P1/2 state. This latter upconverted emission can be attributed to excited-state absorption of the pump radiation. The proposed upconversion mechanisms responsible for the different emissions from levels ²P1/2 and ⁴G7/2 are supported by both the time evolution of the upconversion luminescence after infrared pulsed excitation and the upconversion luminescence excitation spectra.