  We have demonstrated higher-order optical resonance node detection by using
an integrated disk microresonator from through port of the coupling bus
waveguide. In addition to the fundamental mode, the disk resonator has
higher-order whispering gallery modes. The excited second-order higher-order
mode has a node at the position where the electromagnetic energy of the
fundamental mode is close to a maximum. This high resolution measurement of
optical resonance mode profile has a variety of applications for optical
sensing and detection. The self-referencing characteristics of the two optical
resonance modes have potential to achieve optical detection independent of
external perturbation, such as temperature change.
