Gain anticipation of Ho³⁺ in ion-exchangeable germanate waveguide glasses

Efficient infrared emissions at ~ 1.2 and ~ 2.0 µm were recorded in Ho^{3 +}-single-doped and Ho³⁺/Yb³⁺-co-doped aluminum germanate glasses (NMAG), respectively. The maximum stimulated emission cross-sections for the ~ 1.2- and ~ 2.0 µm emissions were derived to be 2.3 × 10⁻²¹ and 5.8 × 10⁻²¹ cm², respectively; then the gain cross-sections were further evaluated and the effective gains have been anticipated. In addition, the channel waveguide fabricated by K⁺–Na⁺ ion-exchanged method exhibited a complete single mode at 1.55 µm and the field diameters were identified to be horizontally 10.6 µm and vertically 6.7 µm. Effective amplified spontaneous emission at ~ 2.0 µm was recorded under 980 nm laser pumping. Broad bandwidth, large emission cross-section and perfect thermal ion-exchangeability indicate that Ho³⁺- and Yb³⁺-doped NMAG glasses are promising for the development of optical amplifier, tunable laser and light source operating at ~ 1.2 and ~ 2.0 µm.