We report controlled manipulation of mode splitting in an optical
microresonator coupled to two nanoprobes. It is demonstrated that, by
controlling the positions of the nanoprobes, the split modes can be tuned
simultaneously or individually and experience crossing or anti-crossing in
frequency and linewidth. A tunable transition between standing wave mode and
travelling wave mode is also observed. Underlying physics is discussed by
developing a two-scatterer model which can be extended to multiple scatterers.
Observed rich dynamics and tunability of split modes in a single microresonator
will find immediate applications in optical sensing, opto-mechanics, filters
and will provide a platform to study strong light-matter interactions in
two-mode cavities.Comment: 9 pages, 5 figures, 14 references. Major revision. Published version
in Optics Expres