Er3+-doped ultratransparent oxyfluoride glass-ceramics for application in the 1.54 micron telecommunication window

Abstract

We have fabricated ultra-transparent glass-ceramics in the system (SiO 2 )(Al 2 O 3 )(CdF 2 )(PbF 2 )(ZnF 2 ): x(ErF 3 ). Intensity, width and Stark-splitting of emission and absorption spectra of Er 3+- dopants at 1.5 micron ( 4 I 13/2 ↔ 4 I 15/2 transitions) change with the size of PbF 2 nano-crystals hosting Er 3+ dopants. We report the broadest and flattest emission spectrum of Er 3+ and largest wavelength divergence of emission and absorption spectra for 4 I 13/2 ↔ 4 I 15/2 transitions to date. Er 3+- dopants are efficient nucleation centres in (SiO 2 )(Al 2 O 3 )(CdF 2 )(PbF 2 )(ZnF 2 ): x (ErF 3 ) oxy-fluoride glasses when heat-treated at 20 to 80°C above glass transition temperature Tg. The emission spectrum of Er 3+- at 1.54 micron for the resulting glass-ceramics (GC) is the broadest (75 nm at the half-height-width in developed GC and up to 90 nm in quasi GC) and flattest (especially between 1530 to 1560 nm in quasi GC) to date to our knowledge. The broadness is of benefit for Erbium Doped Fibre Amplifier (EDFA) operating in the 1.54 μm fibre optic telecommunication window. The flatness is of benefit in the most often employed C-band of EDFA. We have achieved the largest reported wavelength divergence to date in the maximum of absorption (1505 nm) and emission (1544 nm) spectra of Er 3+- in developed GC, which again is of benefit for reduction of noise in the EDFA caused by overlap of emission and absorption bands at about 1.54 μm (i.e. self-absorption). The evolution of spectral behaviour is explained by changes in average site geometry of the Er 3+ dopant, related to the α→β phase transition of PbF 2 , which is stimulated by heat treatment.