Thulium-doped tellurium oxide microring lasers integrated on a low-loss silicon nitride platform

We demonstrate compact, monolithically integrated thulium-doped tellurium oxide microring lasers on a low-loss silicon nitride platform. We observe lasing in the wavelength range of 1815–1895 nm under 1610 nm resonant pumping at varying waveguide-microring gap sizes and on-chip single-sided output powers up to 4.5 mW. The microlasers exhibit thresholds as low as 18 mW (11 mW) and a single-sided slope efficiency as high as 11% (17%) with respect to the pump power coupled into the TeO2:Tm3+-coated Si3N4 bus waveguide (absorbed pump power). These results are a promising development for integrated tellurite glass devices and light sources for the emerging 2-µm band in silicon nitride photonic integrated circuits.