Optical investigation and thermal stabilization of germanium-gallium-containing bismuthate glasses towards NIR-MIR applications

The progress in the utilization of heavy metal oxide glasses in mid-infrared photonic applications has been hindered by the complication of fabricating thermally stable glass compositions as well as optical fibers with acceptable optical losses. To overcome these obstacles, a range of BaO-Ga 2 O 3 -GeO 2 -Bi 2 O 3 glasses were fabricated by increasing the BaO content while decreasing Bi 2 O 3 . Differential scanning calorimetry studies revealed that the thermal stability of the glasses increases up to 27.5 mol% BaO at which the glass does not yield a crystallization peak even at very low heating rates. High linear and nonlinear refractive index of the glasses were also shown. Spectroscopic properties of the thermally most stable glass were investigated by various Er 3+ -doping content. The luminescence spectra and lifetime values showed suitable results, even with high doping content, for applications requiring optical signal amplification. A multimode optical fiber with an undoped core was drawn by rod-in-tube technique which yielded an optical loss of 10 dB/m for a 3-meter-long fiber. With appropriate precursor purification, glass dehydration and glass fabrication optimization steps, BaO-Ga 2 O 3 -GeO 2 -Bi 2 O 3 glasses are important alternatives to PbO-GeO 2 and TeO 2 -based glasses for MIR applications in optical fiber or bulk glass form.