High Quality Factor, High Sensitivity Ta ₂ O ₅ Microring Resonator for Biochemical Sensing

We demonstrate a high-performance Ta.O. microring resonator fabricated using electron-beam lithography and inductively coupled plasma etching. The loaded Q-factor of the fundamental TE mode reaches 3.1 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> at 1550 nm under ambient conditions, with post-annealing at 600 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>C further elevating this value to 5.2 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup>. The waveguide propagation losses in the telecom band is also reduced from 1.3 dB/cm to 0.6 dB/cm with post annealing. For practical validation of sensing capabilities, the device was implemented in sodium chloride concentration detection, achieving a sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula>279 nm/RIU and an intrinsic limit of detection (iLOD) of 1.78 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup>. RIU. This represents the first reported instance of such performance metrics in on-chip Ta<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> microring-based sensors. The synergistic combination of exceptional Q-factor, minimized optical loss, and enhanced detection sensitivity establishes this platform as a compelling candidate for next-generation integrated photonic sensing systems.