Sensitivity and detection limit of dual-waveguide coupled microring resonator biosensors

Abstract

We show that a linear relation exists between the device sensitivity andthe quality (Q) factor of a dual-waveguide coupled microring resonatoroptical biosensor when the optimal conditions are satisfied. We alsoshow that the detection limit depends on the loss coefficient andsignal-to-nosie ratio (SNR) of the overall system, rather than thecircumference of the ring. For a microring resonator sensor whose Qfactor is 20000, the detection limit is found to be about 10(-7) with30-dB SNR, which is in good agreement with reported experimental data.These results indicate that loss reduction is the top priority in thedesign and fabrication of highly sensitive microring resonator opticalbiosensors.