  We develop a compact whispering-gallery-mode (WGM) sensing system by
integrating multiple components, including a tunable laser, a temperature
controller, a function generator, an oscilloscope, a photodiode detector, and a
testing computer, into a phone-sized embedded system. We demonstrate a thermal
sensing experiment by using this portable system. Such a system successfully
eliminates bulky measurement equipment required for characterizing optical
resonators and will open up new avenues for practical sensing applications by
using ultra-high Q WGM resonators.
