Fig. 4

Integrated FNW-SW-resonators for on-chip light generation. The active FNWs used here are Er³⁺/Yb³⁺-codoped tellurite glass nanofibers. a SEM image of a 121-μm-perimeter racetrack resonator integrated with a 193-μm-length 980-nm-diameter tellurite glass FNW. Scale bar, 10 μm. b Optical micrograph of the integrated FNW-SW-resonators under a 976-nm-wavelength excitation from a tapered fiber probe. Green light observed on the excited FNW is attributed to the up-conversion luminescence of Er³⁺ ions. Scale bar, 50 μm. c Output signal collected in the drop waveguide of the racetrack resonator in b. d Output signal from a 50-μm-perimeter SW resonator integrated with a 960-nm-diameter 216-μm-length tellurite glass FNW. Scale bar, 20 μm