Room-temperature near infrared emission and green up-conversion in PbMoO4:Er3+ crystals

Near infrared emission at ∼1550 nm and green up-conversion emission at ∼550 nm and ∼520 nm in PbMoO4:Er3+ crystals as a result of the Er3+ 4f−4f transitions have been observed under 980 nm excitation. The PL emission spectra and dependences of the PL intensities as function of the excitation power are provided to investigate the up-conversion mechanism. The up-conversion mechanism based on the double-stage excited-state absorption (ESA) are suggested and discussed.