  The next frontier in photonics will rely on the synergistic combination of
disparate material systems. One unique organic molecule is azobenzene. This
molecule can reversibly change conformations when optically excited in the blue
(trans-to-cis) or mid-IR (cis-to-trans). Here, we demonstrate SiO2 optical
resonators modified with a monolayer of azobenzene-containing
4-(4-diethylaminophenylazo)pyridine (Aazo) with quality factors over 106. Using
a pair of lasers, the molecule is reversibly flipped between molecular
conformations, inducing resonant wavelength shifts, and multiple switching
cycles are demonstrated. The magnitude of the shift scales with the relative
surface density of Aazo. The experimental data agrees with theoretical
modeling.
