Erbium doped silica microspheres for lasing applications

Silica microspheres were made by melting the tip of a standard telecom fiber. They were coated using a dip coating apparatus with a 70% SiO
2
- 30 HfO
2
sol-gel derived glass activated by 0.3 % mol of Er
³⁺
. The whispering gallery modes of the coated resonator were studied using a full taper - microsphere coupling setup. Upon excitation at 1480 nm sharp peaks in the wavelength range from 1540–1565 nm were observed pertaining to the lasing modes of the microresonator.