Thulium-doped tellurium oxide waveguide amplifier with 7.6  dB net gain on a silicon nitride chip.

We report on thulium-doped waveguide amplifiers integrated on a low-loss silicon nitride platform. The amplifier structure consists of a thulium-doped tellurium oxide thin film coated on a silicon nitride strip waveguide on silicon. We determine a waveguide background loss of 0.7 dB/cm at 1479 nm based on the quality factor measured in microring resonators. Gain measurements were carried out in straight and 6.7-cm-long s-bend waveguides …