An All-Fiber Coupled Multicolor Microspherical Light Source

We present results on the realization of an all-taper coupled, multicolor microspherical light source fabricated from the erbium-doped fluoride glass ZBLALiP. Whispering gallery mode lasing at 1555 nm and fluorescent emissions from the ultraviolet to the infrared (IR) have been observed. A tapered fiber is used to launch 980-nm pump light into the microresonator cavity and to collect the resulting IR lasing. A separate, half-taper fiber is used to outcouple the upconversion spectrum over several hundred nanometers. A number of discrete emissions from 400 to 850 nm have been observed in the upconversion spectrum, indicating the suitability of this scheme as a miniature device with a 450-nm-wide band and reasonable output coupling efficiency.