Characterization of Mid-Infrared Silicon-on-Sapphire Microring Resonators With Thermal Tuning

Microring resonators on silicon-on-sapphire (SOS) were characterized at 2.75
$\mu\hbox{m}$
wavelength. We obtained a
$Q$
factor of 11400
$\pm$
800. The thermo-optic coefficient of epitaxial silicon of SOS wafer was measured to be
$2.11 \pm 0.08 \times 10^{-4}\ \hbox{K}^{-1}$
. We also describe a characterization technique to measure the
$Q$
of microring resonators using a fixed wavelength source. By only varying the temperature of the device, it is possible to measure the
$Q$
of a mid-infrared (mid-IR) microresonator. The proposed method provides an alternative method of
$Q$
measurement for microring resonators in mid-IR, where tunable lasers may not be easily available. The technique was used to determine the
$Q$
of SOS microring resonators at 2.75
$\mu\hbox{m}$
wavelength.