Er³⁺ doped tellurite glass for whispering gallery mode microsphere laser production

Whispering gallery mode microspheres have garnered considerable attention due to their applications in signal processing and telecommunications. Unique properties such as high quality factor and small mode volume of whispering-gallery mode microspheres make them suitable for laser applications with a low pumping power requirement and narrow emission linewidth. Tellurite glass is a promising material for making microlasers because of its high transparency range, high refractive index, and it has been proven as a good host for rare earth ions leading to powerful and broad stimulated emission cross section. We reported lasing in Er³⁺ doped tellurite glass microspheres fabricated using the plasma torch method. 15Na₂O₂5WO₃60TeO₂ doped with 0.5 mol% Er³⁺ is used for the fabrication of microspheres. Laser light from the pump is coupled to the microsphere through a half and a full tapered fiber. An optical spectrum analyzer receives the counter propagating light from the microsphere. A pump laser of 980 nm is used to achieve the laser emission at 1570 nm.