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

Abstract

Microring resonators on silicon-on-sapphire (SOS) were characterized at 2.75 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\mu\hbox{m}$</tex></formula> wavelength. We obtained a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$</tex></formula> factor of 11400 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm$</tex></formula> 800. The thermo-optic coefficient of epitaxial silicon of SOS wafer was measured to be <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$2.11 \pm 0.08 \times 10^{-4}\ \hbox{K}^{-1}$</tex></formula> . We also describe a characterization technique to measure the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$</tex></formula> of microring resonators using a fixed wavelength source. By only varying the temperature of the device, it is possible to measure the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$ </tex></formula> of a mid-infrared (mid-IR) microresonator. The proposed method provides an alternative method of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$</tex></formula> measurement for microring resonators in mid-IR, where tunable lasers may not be easily available. The technique was used to determine the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$ </tex></formula> of SOS microring resonators at 2.75 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> wavelength.